ASPECTS OF NIGHT LIGHTING IN THE GARDEN

By

CHARLES CLAYTON ElSCHER

A THESIS

Submitted to the School for Advanced Graduate Studies of Michigan
State University of Agriculture and Applied Science

in partial fulfillment of the requirements
for the degree of

‘/

MASTER OF SCIENCE _\

Department of Horticulture g;

1956 \

THESIS

ACKNOWLEDGMENTS

The author expresses sincere appreciation to Professor Donald
P. Watson, under whose direction the investigation was conducted. To
Dr. Fred B. Widmoyer, Jr- for his valuable assistance. To Barbara
Ann Fischer for her patient encouragement.

Acknowledgment is extended to: Cottage Gardens Nursery,
Lansing; Laetz Hobby Farm Nursery, Bay City; McDonald Nursery,
Saginaw; Miller Nursery, Jackson; and Stark Nursery, Midland for the

loan of plant materials.

 

11“ ‘ 'I It- I

TABLE OF CONTENTS

INTRODUCTION .
LITERATURE REVIEW.
Early Development .
Lighting Fixtures .
Effect on Plants
Good Effects in Garden
PROCEDURE .
Effect on Plants.
Good Effects in Garden
DISCUSSION OF RESULTS .
Effect on Plants .
Greenhouse Study: .
Outdoor Study: .
Lighting in the Garden .
Observations of Lighting: .
Suggested Techniques: .
SUMMARY .

BIBLICXSRAPHY .

Page

.10
10
13
15
15
15
22
23
23
24
33

35

INTRODUCTION

The practice of lighting home gardens at night is becoming in-
creasingly popular in the United States. The spring, summer and fall
seasons in most parts of the country provide countless evening hours of
outdoor enjoyment which can not be appreciated without artificial illum~
ination. In recognition of this potentiality numerous manufacturers of
electrical equipment have been interested in outdoor night lighting of
gardens. These manufacturers have developed extensive equipment
which is available to the home owners.

Many requests have been received from nurserymen, operators
of garden stores, and landscape gardeners for information about the use
of night lighting. They wish to assist the home owners with installation
of lights. This will extend their season of sales into the summer and
winter months when there is more free time to devote to this work.

The present investigation was conducted to provide information
to improve existing practices of garden lighting, with emphasis upon de-
veloping new lighting techniques by accenting the plantmaterial. Standard
lighting practices were studied to improve recommendations, as well as to
study the inﬂuence of additional illumination of various wave lengths on the

growth habits of selected garden plants.

 

‘II l.|||ll| I‘ll! ‘ll ‘lllllill'l‘

LITERATURE REVIEW

Early Development

 

Some of the earliest outdoor night lighting in the United States was
used to illuminate Niagara. Falls, New York, and the Natural Bridge, Vir-
ginia, as a tourist attraction (Rodes, 1936). An editorial in Business Week,
1954 stated that by the late 1930s home owners were interested. It explained
that shOrtages created by the second world war (1941- 1945) temporarily
terminated the electrical supplies and that since then at least five electrical
manufacturers have conducted research programs to improve equipment and
promote lighting.

The increase of suburban homes (Fossum, 1953) and the use of
small homes account for the increased use of outdoor garden lighting. These
smaller homes employ picture windows to add a feeling of spaciousness
(Business Week, 1954). This is effective during the day, but outside lights
are needed to create this same effect of spaciousness at night (Business
Week, 1954).

Lighting Fixtures

 

It has been stated that the appearance of light fixtures in the day-
light is important to their placement in the landscape (Southern Florist and
Nurseryman, 1955). The Scientific American in 1936 cautioned that the

appearance of a beautiful garden might be destroyed by visible light sources.

 

.III. I. llllil {Itli '1‘ III-Illl‘ IP‘ I ‘Illll

For the best effect, lighting equipment should be invisible or concealed
with natural plant material (Ashworth, 1936; Greeves-Carpenter, 1941;
Popular Mechanics, 1935; Rodes, 1936; Warren, 1937). Concealment of
the light fixtures eliminates any feeling of artificiality in the landscape
(Warren, 1937). Equipment small enough for easy concealment and others
which are attractively designed are available (Bowser, 1954). Many of the
lighting fixtures may be utilitarian by lighting walks and steps as well as
creating aesthetic effects with plants in the garden (Sunset, 1956) Others
may light an outdoor dinner table (Life, 1954) or supply light for garden
work after dark (Bowser, 1954).

Many of the lighting fixtures available for outdoor garden use have
been illustrated (Hibben, 1940; Howland, 1955 ; Popular Mechanics, 1935;
Quaintance, 1939; Rebhan, 1955). This equipment included standard flood
lights and spot lights and some more ornamental designs simulating objects
commonly found in a garden. The Scientific American, 1936 illustrated
lighting fixtures which appeared as bird-houses. Other examples of unique
designs were those which resembled lily pads, tree stumps, flowers and
other plant materials (Greeves-Carpenter, 1941; Polster and Fahsbender,

1954).

 

Isl-III"

4l.l\{l|lll. ll Illl lulillullx all i ‘l.

Effect 92 Plants

 

Investigators have utilized various types of lamps for photoperiodic
research. Poesch (1935) reported Mazda lamps superior to mercury and
neon sources in producing earlier flowering, greater ﬂower production and

stem length of annual Chrysanthemum, Calceolaria, Didiscus, Leptgsylle,

 

 

Viola, and Tagetes. Further, he found (1936) that ﬂowering of Chrysanthe-

 

_n_1_t£n was retarded more effectively by Mazda lamps than daylight, medium
and light blue, and mercury lamps. Post demonstrated in 1942 that incan-
descent bulbs properly fitted with reﬂectors obtained maximum light effi-
ciency for growth and ﬂowering of florist crops. Withrow and Withrow

(1947) showed incandelscent sources gave as good or better growth responses

than ﬂuorescent or mercury types with Callistephus_, Glycine, and Lyco-

 

persicum.

 

Other investigators have studied the effects of increased daylength
with artificial light on the growth and ﬂowering of plants. Laurie in 1930
reported results of additional illumination consistent for "long day" plants.
Earlier maturity, increased number of flowering stems, and longer stems

were the significant results with the following plants: Antirrhinum, Calen-

 

 

dula, Dianthus, bulb crops and pot plants. Hydrangea responded to an addi-
tional photoperiod with increased plant height and stem length during the
growing season (Piringer and Stuart, 1955). Long photoperiods increased

the length of lateral shoots of Chrysanthemum (Post, 1950).

 

The effect of light quality was reported by Vince in 1956; total dry

weight of the species Lycopersicon and Pisum was greatest in red light and

 

in the complete spectrum, and least in green and blue light. Post (1942)
advised that temperature control and daylength were equally important for
flower bud formation of most ﬂorist crops. Increased illumination resulted
in earlier ﬂowering of Lathyrus and bulb crops (Laurie, 1930). He found

Dianthus, Gladiolus and Lathyrus responded by increased ﬂower production.

 

Earlier ﬂower initiation of Callistephus occurred with long day treatments

 

(Lin and Watson, 1950). Poesch reported in 1931 earlier ﬂowering of annual,

perennial and potted plants and heavier ﬂowering of 1_r_i_s and Viola when

 

forced with artificial light. Withrow and Benedict (1936) demonstrated that

Callistephus, when grown under all wave lengths of additional light, as well

 

as Viola and Mathiola under orange-red bands of light responded with earlier

 

flowering. All three genera had greatest fresh weight and top-root ratio
under the orange and red radiation. Gardenia ﬂower production was in-
creased by supplementary illumination and a temperature of 70° F, followed
by an unstated low temperature during the dark period (Keyes, 1939).

Harmful effects of additional illumination by retarding Poinsettia
ﬂowering were reported by Laurie in .1930. Under supplementary daylengths
I the Cattleya orchid delayed ﬂower bud development (Holdson and Laurie,

1951) Cooper and Watson (1952) reported cleistogamous ﬂowering of

Viola when exposed to extended periods of additional illumination. Poesch

in 1936 found Chrysanthemum bud differentiation retarded when supplementary

 

light was applied.

In general, the use of supplementary lights resulted in earlier
flowering of selected annuals and bulb crops (Laurie, 1930; Lin and Wat son,
1950; Poesch, 1931 and 1935; Post, 1942; Withrow and Benedict, 1936;
Withrow and Withrow, 1947). In addition to earlier ﬂowering various per-
ennial plants responded with increased flower production and greater growth
(Piringer, 1955; Poesch, 1931; Post, 1942). Some greenhouse crops sub—
jected to additional illumination also had increased growth, earlier ﬂower-
ing and increased ﬂower production (Keyes, 1939; Laurie, 1930; and Post,
1942 and 1950).

Good Effects _i_n_Garden

 

 

The most popular and aesthetically effective technique of illuminat-
ing home grounds was to emphasize the plant materials in the garden (Better
Homes and Gardens, 1948; Howland, 1955; Life, 1954; Rebhan, 1955; Rodes,
1936; Southern Florist and Nurseryman, 1955; Toland, 1934). This type of
lighting was adopted for larger gardens and municipal parks (Cutler and
LaWall, 1934; Hibben, 1940).

The practice of night lighting in the landscape had other advantages.

It was used for recreational areas, safety lighting along walks, steps and

drives and for such utilitarian purposes as outdoor work after dark. Better
Homes and Gardens, 1948; Bowser, .1954; Howland, 1955; Life, 1954;
Southern Florist and Nurseryman, 1955; Sunset, 1956 have provided illus-
trations of these specialized phases of garden lighting.

The lightweight, portable fixtures and extension cords were best as
temporary preliminary outdoor lighting to determine the best locations for
permanent wiring and outlets (Rebhan, 1955). Later permanent outlets
could be installed more effectively at central points in the landscape;

Rodes (1936) allowing the freedom for seasonal movement of the lighting
fixtures. Procedure for wiring and installation of electrical outlets have
been illustrated by Corey (1954); Heath (1938) and Hibben (1940).

Stern (1954) stated that outdoor lighting was a valuable garden in-
vestment which greatly increased the utility and beauty of a landscape by
providing added hours of enjoyment. Business Week, 1954 recommended
night lighting as a ”relatively inexpensive decorative scheme for the aver-
age suburban home". Life magazine, 1954 stressed small operating costs
for most homes, and estimated a year's electric bill of about $20 for out-
door night lighting.

To create good effects with outside lighting the best features of
the landscape are emphasized and the poorest features eliminated by shadows
(Life, 1954; Quaintance, 1939; Warren, 1937). This procedure often causes

the lighted garden to appear more beautiful than during the day (Ashworth,

 

I.i I‘ lx‘.l.1llt Iii

1936). No definite rules or methods are essential to insure this result.
Toland in 1939 concluded that subtle effect of lighting requires the discreet
use of few lights with sources well concealed. Greeves-Carpenter (1941),
Kroscher (1933) and Quaintance (1939) recommended experimenting with
the location, size, angle and color of the light until the best effect was ob-
tained.

Utilizing a flood light to establish an over-all basic illumination
was effective in addition to the accent lighting of outstanding garden features
according to Howland (1955) and Rodes (1936). Popular Mechanics (1935)
suggested flood lights were useful for emphasizing the background of a gar-
den. Accent lighting, or concentration of light on specimen plants resulted
in a monotonous two-dimensional appearance. Rodes in 1939, advised the
use of two light sources from different angles and intensities to avoid the
effect of "flatness"

The colors and textures of plant materials are emphasized with
night lighting (Rebhan, 1955). By utilizing tinted lights predominately the
same color as the plant material, the best results can be achieved (Person,
1932). An impression of depth and distance can be created by side place-
ment of the lighting fixtures and utilization of blue and purple colored lights
(Person, 1932; Rebhan, 1955). Quaintance (1939) suggested the use of white

and blue colors or two lights of unequal intensity to achieve contrast. Ash-

worth in 1936 preferred numerous colors when lighting water in garden
pools, especially fountains and waterfalls. The yellow and orange light
sources do not attract ﬂying insects when used for night garden lighting
(Bowser, 1954; Person, 1932; Rebhan, 1955).

The most widely used type of light source for outdoor illumina—
tion is the incandescent lamp. The mercury-vapor sources have had

limited application in garden lighting (Hibben, 1940; Howland, 1955).

10.

PROCEDURE

Effect g Plants

 

 

To study the inﬂuence of colored light on representative garden
plants, a preliminary investigation was conducted at the Plant Science green-
house in a four by fifty foot bench using a night temperature of 60° F. The
bench was equally divided to form six individual areas, each separated by a
black polyethylene strip. To prevent reflection of light, an overhead wire
frame was constructed with black shading cloth to cover the area.

Plant material was selected to provide representative groups of
plants commonly used in Michigan gardens. Mixed seedlings ofm

elegans; rooted cuttings of Chrysanthemum morifolium cultivar Indianapolis

 

White and Yellow; rooted cuttings of Pelargonium hortorum cultivar Scarlet

 

Princess; Spiraea vanhouttei; Euonymus vegetus; Juniperus chinensis colum-

naris; and Taxus media hicksii were chosen to represent annual, perennial,

 

deciduous, and evergreen ornamental plants.

After approximately five months, on February 1, 1955, electrical
outlets were installed in each of five areas and one space left unlighted
Four 100-watt incandescent lamps were the source of additional light in each
area which received blue, green, red, white or yellow light from these four
lamps. Additional light was given the test plants between 5 and 12 p. m. ,

using an automatic timing device.

II

The following was recorded: total growth, time and amount of

 

ﬂowering of Chrysanthemum; number and elongation of new shoots of Euony—

_r_nu_s_; the time of flowering, stem length and plant height of Pelargonium and

 

Zinnia; plant height and amount of growth of Juniperus, Spirea and Taxus.

 

 

A second investigation was conducted in outdoor planting beds.
Four beds of equal size were constructed southeast of the Plant Science
greenhouse. Each area was enclosed on all sides with canvas to eliminate
light reflection.

A different and more representative selection of plant material was

 

used in this study; as annuals Callistephus chinensis and Salvia splendeth,

 

Coreopsis lanceolata and Delphinium cultorum to represent herbaceous per—

 

 

ennial plants; Deutzia lemoinei, Euonymus alata compacta, Hypericum pro-

 

lificum and Rosa hybrids to represent deciduous perennials, and Buxus

 

sempervirens and Juniperus Pfitzeriana to represent broad and narrow-leaved

 

 

 

evergreens.
After two weeks, on July 1, 1955, electrical outlets were installed
as before using three lOO-watt incandescent lamps as a source of green,
white and yellow light.
Amount of frost injury was observed for the annuals, the herbaceous
perennials and some of the woody deciduous perennials. In addition, the
condition of winter hardiness and dormancy were recorded for some of the

perennials and the evergreens.

12.

Plants of Chrysanthemum morifolium cultivar Indianapolis Yellow,

 

 

 

“Mn-*—

 

Chrysanthemum morifolium cultivar Corsair, Dianthus caryophyllus, and

 

Rosa hybrids were sprayed with a fluorescent paint" to test the effect upon
the selected plant materials.

The lOO-watt lamps used in the investigations were sprayed with
blue, green, yellow and red paint. The wave length transmittions (Table l)
of these colored incandescent lamps were obtained by using a Bausch and

Lomb spect roscope

Table l

The Wave Length Transmittions of lOO-Watt Lamps.

 

 

 

Lamp Color Angstrom. Units
Blue 4100 — 7600
White 4250 - 7600
Green 4650 - 7150
Yellow 5100 - 7250
Red 6000 - 7400

 

 

_ — __. ._ ._ —- —— — —— —. — —— _— .— —_ _—

Day-Glo, made by the Craftint Manufacturing Company, Cleveland, Ohio

13

Good Effects igGarden

 

The illumination of a private residence in June, 1955, the horti-
cultural garden at Michigan State University in January, 1956, and Jones
Nursery in Grand Rapids in 1956, served as examples of lighting proced-
ure. The development of new techniques of lighting was emphasized in
order to accentuate plants. Standard lighting equipment (Figure l) in-
cluding many designs of spot lights, ﬂood lights, colored lenses, incan-
descent lamps and waterproofed extension cords were used. Part of the
lighting equipment was supplied by Steber Manufacturing Company,

Broadview, Illinois.

I4.

 

Three lamp unit
mounted on adjust-
able extension pole

 

Fixture with ground spike.

For PAR-38 flood or spot lamps.
Convenient outlet for adding
extra fixtures.

 

 

 

PAR-38 sealed beam
lamp and lensholder.
Spring clip holds blue,
green, red or yellow
glass lenses in place.

   

Enclosed ﬂoodlight, re-
sistant to moisture, heat
or cold Lenses may be
clear or colored.

 

 

Figure 1. Examples of standard lighting equipment.

15.

DISCUSSION OF RESULTS

Effect 31} Plants

 

 

Greenhouse Study: All Zinnia elegans plants grown under additional

 

 

illumination of white lamps were inhibited in linear growth (Table 2). The
average stem length of the other lighted plants was greater than the unlighted
plants. Those exposed to the green source of light had a total of six inches
additional elongation compared with those receiving no supplementary illum-
ination The green and red lighted plants had significantly more linear
growth than those exposed to the white light.

As shown in Table 2, the plants which received no supplementary
illumination produced approximately twice as many ﬂowers as the lighted
plants. Of those receiving additional light, the red source stimulated the
greatest flower production. There was no significant difference in ﬂower
diameter on plants grown under the blue, green, red and yellow light,
but the plants grown under the white light produced ﬂowers which were re-
duced approximately one inch in diameter.

In general, plants of Zinnia elegans responded to additional illum-

 

ination with greater linear growth and a larger ﬂower diameter. Support
of these findings was offered by Post in 1942, when he found stem length
and ﬂower size increased with supplementary light. Total ﬂower produc-

tion was inhibited with the use of longer photoperiods. Those plants grown

Table 2

16.

Growth Responses of Zinnia elegans to Various Wave Lengths of Light
(Average of Five Plants).

 

 

 

Wave Lengt hs

Length of Stem Total Number of

Flower Diameter

 

(Inches) Flowers (Inches)
Blue .14. 96 1. 75 2. 89
Green 18.14 1.75 2.60
Red 16.14 2.25 2.. 91
White 9. 55 1.63 1. 90
Yellow 14.13 1. 88 2. 90
Unlighted 12.13 3. 13 2 45
LSD .05 5. 99 1 22 . 87
.' 01 8. 02 NS NS

 

 

with white light were consistently inhibited in linear growth, total ﬂower

production and size of ﬂower.

The results of the experiment presented in

Table 2 and by Post showed that ﬂower production was greatest for those

plants which received no additional light.

The linear growth of Chrysanthemum morifolium exposed to various

 

light sources showed highly significant increases in stem length (Table 3).

A comparison of plants grown under the light sources shows that no one

wave length was superior to any other in the production of growth. The

Chrysanthemums receiving no additional light were grown with naturally

17.

Table 3

The Effect of Various Qualities of Light on Growth of Chrysanthemum mori-
folium and Euomus vegetus (Average of Five Plants).

 

 

 

 

 

 

Chrysanthemum Euonymus
Wave Length Stem Length (Inches) Number of Stem Length
Shoots (Inches)

Blue 7. 20 4 25 3 85
Green 6 46 _ 2 50 3. 38
Red 6. 60 11.00 6. 43
White 6- 80 5.. 00 2. 63
Yellow 6. l4 6.. 50 3 20
Unlighted 3 88 14. 00 4 23
LSD . 05 1.84 6 48 3. 73

. 01 2. 51 NS NS

 

 

short photoperiods of the latitude and resulted in uniform ﬂowering, as
was previously shown by Post (1948). Those plants exposed to a longer
photoperiod exhibited retarded ﬂowering, a finding confirmed by Poesch
(1936). The use of additional light of all wave lengths stimulated vegetative

growth of Chrysanthemum; the unlighted plants ﬂowering on short stems.

 

Table 3 lists the number of new shoots being inhibited on Euonymus
vegetus grown under blue, green, white and yellow light sources. Euonymus
plants exposed to red illumination produced significantly more new shoots

than other lighted plants, although this was an average of three shoots less

18.

than the unlighted plants. A comparison of the plants which received addi-
tional light shows red illumination promoted the largest number of new
shoots and greatest elongation. All plants grown under longer photoperiods
had reduced total elongation with the exception of those receiving the red
source of light. These plants produced an average of 2. 2 inches more linear
growth than the unlighted test plants. Euonymus was inhibted in the develop-
ment of new shoots when exposed to additional illumination. In general,
the plants were inhibited in total stem elongation. During the first four
months of this experiment, all Euonymus test plants remained in a dormant
condition, which was broken by exposing the plants to a two-week cold per-
iod (32 to 35° F)

These data show in Table 4 that the average flower production of

Pelargonium hortorum was inhibited by supplementary illumination. This

 

inhibition was highly significant for the green and yellow sources as com-
pared with the plants exposed to blue illumination and those which remained
unlighted. Total ﬂower production was increased when plants were grown
with blue, red and white light, over those which received normal daylength.
The blue and red sources of illumination promoted greater total ﬂower pro-
duction than any other color.

All Pelargonium plants grown under additional light produced longer
ﬂower stems than unlighted plants. This was a highly significant result for

all test plants, with the exception of those exposed to white light. When

Table 4

l9.

Flowering Responses of Pelargonium hortorum to Selected Wave Lengths of
Artificial Illumination (Average for Five Plants).

 

 

 

Wave Lengths

Average Number Total Number

of Flowers of Flowers

Flower Stem
Len gt h (I nches)

 

Blue

Green

Red

White

Yellow

Unli ght ed
LSD 05

.01

1.96

1.46

1.74

1.68

1.48

1,92

.29

.40

22.

13

20.

18,

15.

18.

80

80

60

80

80

60

.45

.44

5.. 38

5.90

6.. 64

5. 20

5.76

4.44

69

94

 

 

comparing the lighted plants, the green and red sources produced the long-

est ﬂower stems

In general, the use of additional light inhibited average ﬂower

production of Pelargonium hortorum. The total ﬂower production was in-

 

creased under blue, red and white light, as compared with unlighted plants.

All plants grown under supplementary illumination produced longer ﬂower

stems. These findings are contrary to Post (1942), who found that daylength

did not affect the ﬂowering of Pelargonium hortorum Plants exposed to

 

20.

longer daylengths had an average of 9. 4 inches greater height than those
not given additional light. This response was especially evidenced by the
plants grown under red light which had an average 21. 8 inches greater
height than the unlighted. This agrees with Vince (1956) who noted total

stem and internode length of Lycopersicon species increased with increases

 

in wave lengths of light.

Table 5

Linear Growth Response of Taxus media hicksii, Juniperus chinensis colum-
naris and Spiraea vanhouttei to Selected Light Qualities.

 

 

 

 

Wave Len gt hs Taxu s* Juniperu s* * Spiraea"

—.———.——-———n

(length given in inches)

 

 

 

Blue 2.50 19.0 11.52
Green 2. 88 16.0 12.88
Red 214 21.5 11.74
White 2 30 1.5 12.20
Yellow 2.10 14.3 11.92
Unlighted 2. 74 15. 0 10.82
LSD .05 NS -- NS

 

 

*Average for five plants.

MInsufficient plants for statistical analysis due to a high mortality rate.

21.

Growth of Taxus media hicksii in general was slightly inhibited

 

by additional illumination (Table 5). Plants grown under the red source of
light were an exception, although growth was not sufficiently greater than
the unlighted plants. The response comparison between lighted plants
showed the red and yellow sources of illumination had the greatest inhibit-
ing effect on growth.

Data in Table 5 show further that Juni_p_e_ry_s chinensis columnaris

 

responded to supplementary light of blue, green and red sources with an
increased growth. The greatest response was shown for the red illumina-
tion which averaged 6. 5 inches over the unlighted plants. The white source
of light apparently had the most inhibiting effect on growth “19111291115

Spiraea vanhouttei grown under additional light had increased

 

linear growth over those which received normal daylength (Table 5) Plants
exposed to the green and white sources of light were the most inﬂuenced,
averaging l. 7 inches more growth than those with no additional illumination.
The response of the woody plants grown with supplementary light

was not consistent among the genera. According to Table 5, Taxus showed
an inhibition of growth with additional light of the various sources with the
exception of red wave lengths The growth of Juniperus was increased when
supplementary light of blue, green and red sources were used. An inhibi-
tion of linear grth occurred for those plants given additional white and

yellow light. Spiraea exhibited uniform increases of late :al grth when

22

supplied with additional light, which were observed but were not sufficient-
ly significant.

Outdoor Study: Experimental plants of Callistephus chinensis,

 

 

Salvia splendens, Coreopsis lanceolata, Delphinium cultorum, Deutzia

 

 

lemoinei, Euonymus alata compacta, Hypericum prolificum, Rosa hybrids,

 

 

Buxus sempervirens and Juniperus Pfitzeriana were examined weekly to

 

 

compare the time of frost injury No differences were observed in time of
frost injury as a result of lighting Time of defoliation, as a measure of
dormancy, varied from October 24 for Deutzia to November 30, 1955 for

Rosa. The annuals were killed by frost earlier. The only genera which

 

light had any inﬂuence on time of defoliation was Euonymus. When these
plants were grown under white light the defoliation was complete on
November 18, six days later than other plants.

The use of additional illumination apparently influenced germina-
tion and growth of weeds. Few weeds germinated in any of the lighted beds.
Of the lighted areas, the white source was less effective in inhibition as
compared with the green and yellow areas where fewer weeds germinated

Heat from the lights in this experiment was not sufficient to pre-
vent frost injury under the autumn of 1955 weather conditions. It would be
necessary to extend this test for several years to be certain that lights

were of no value as a frost preventative measure

23.

The Buxus and Rosa exhibited slight winter injury. which was con-

 

 

sistent in all plots. Observations during the spring of 1956 showed uniform
development and growth for all plants. No inhibitory effects were caused
by the continued lighting of the plants.

Lighting in tile (£11512

Observations 31: Lighting: An objective of night garden lighting

 

is to increase the hours of outdoor living and enjoyment. The spring, sum-
mer and fall seasons offer pleasant evenings which have limited enjoyment
after sundown. With few carefully located lighting units the beauty of trees,
shrubs and ﬂowers can be emphasized and the landscape enjoyed after dark.

Integration of indoor-outdoor living areas has become a standard
landscape practice. The use of garden lighting can effect this integration
during the hours of darkness. This lighting will also serve to feature a
residence in a proper setting after dark

At night the good features, the points of greatest current inter-
est may be emphasized and others left unlighted to create a beautiful gar-
den Careful placement of lighting fixtures and selection of colors to
accent foliage and texture of plant materials can improve the appearance
of most plants. Lighting which emphasizes the beauty of a garden should
be planned to be functional. Light reﬂection can illuminate recreational
areas, garden walks or steps.

This paper is supplemented with three kodachrome transparencies

24

for better illustration of the following techniques.

Suggested Techniques: A fundamental requirement for effective

 

night lighting of gardens was the concealment of all light sources. This
has been recognized by Ashworth (1936), Greeves-Carpenter (1941), Rodes
(1936), and Warren (1937). When lighted, exposed fixtures produce a glare
of light which distracts from the garden and during the daylight hours they
rarely add to the beauty of the setting. Plant material may conceal light-
ing fixtures, especially when smaller units are used.

If the lighting units were used on the ground, they were placed
behind low growing shrubs or other plants for concealment from the main
viewing areas When the fixtures were used in elevated positions they
were hidden among tree branches or an unexposed area of a building. Howland
(1955) also recommended this treatment for elevated light sources.

After the fixtures were carefully concealed for night-time appear-
ance, they were not in a position to distract from the beauty of a garden
during the daytime

Lighting units were hidden by metal sheets. Southern Florist
and Nurseryman (1955) also found this an effective means of concealing
the lighting fixtures. These shielding devices of non-rusting material were
placed close to the light source, thus eliminating glare. Although these
shields resulted in an unattractive daytime appearance in the garden, they

were frequently useful for temporary lighting.

25.

When fixtures were not concealed with existing plant material
or shields, they were sunken beneath the soil. During this study, an in-
expensive fixture was designed. An 8-inch clay pot and waterproof electri-
cal wiring was utilized as a practical unit for submerging (Figure 2). By
inserting the electrical cord through the drainage hole in the bottom of the
pot the socket and lamp was wired in position. Sides of the pot were lined
with aluminum foil which served as a reﬂector for the lamp This entire
unit was buried under the turf to completely hide the fixture and allow for
easier clipping of the lawn.

When outdoor lighting was used on home grounds, especially with
foundation plantings, an interesting technique was added to the lighting by
creating shadows on walls. This emphasized the plant texture and resulted
in unusual shapes and patterns. A method of lighting shadows was developed
during this study. By creating shadows with one source of light, a second
fixture was used to illuminate and add color to the shadows. Figure 3
shows how the shadow of a Juniperus was formed by placing a ISO-watt
fixture in front of the plant. This achieved an outline on the brick wall and
accented the growth pattern of the vine Immediately behind the evergreen
a unit containing a 100-watt colored lamp was located to light the shadow.
The intensity of the first lamp was strong enough to prevent an overlap of
colors. This technique was used with various color combinations. Use of

green and white, as in the illustration, achieved an illusion of a double planting

Figure 2 Practical lighting unit for concealment below
surface of soil.

 

Turf

Clay pot

Aluminum foil reﬂector
Lamp

Waterproof socket
Electrical cord

7919.009”?

,1,” 1.! “WM

26

27.

 

 

 

 

Figure 3
Shadow Lighting Technique

Shadow of Juniperus sp. created
by a ISO-watt spotlamp. The
shadow was then lighted by con-
cealing a 100-watt green lamp
behind the evergreen.

28

To accent specimen shrubs a ﬂood lamp was used as a back-
ground light, a method suggested by Howland (1955) and earlier by Rodes
(1936) Figure 4 is an application of accent lighting used on a simple
planting. The principal function of the background light was the addition
of the illusion of depth to the scene secondary to the accent light

Unusual effects were attained using colored lamps or colored
cover lenses attached to regular lamps. The predominate color of the
plant material was accentuated if an analogous color of light was used.
This method was effectively utilized when lighting branches, trunks,
foliage or ﬂowers

The use of colored light sources for winter lighting added much
interest and subtle effect to the dormant garden It was found necessary to
caution against a bizarre and unnatural scene. Figure 5 provides an ex-
ample of good color use in the winter landscape. To emphasize the natural
branch color of the M, a red lens was used on a 150-watt spotlamp.
Two smaller units supplied white light to add width to the lighted scene.

A fourth fixture containing a 150-watt ﬂoodlamp fitted with a green lens
was used to create depth by lighting the background planting of M

occidentalis.

 

Color was used to reduce attraction of ﬂying insects in a night

lighted garden. Bowser (1954), Person (1932) and Rebhan (1955) suggested

 

 

 

 

Figure 4
Accent Lighting Specimen Shrubs

The specimen Syringa persica was
accented with a 75-watt unit. -
Background Syringa chinensis was
lighted with a ISO-watt ﬂoodlamp.

 

 

29.

 

 

Figure 5
Color in the Winter Garden

Natural bark color of Malus ﬂori-
bunda emphasized by red lens on

PAR-38 spotlamp.

The white side lights added width,

 

 

while the green ﬂoodlamp created depth.

 

 

30.

31.

this effective means of reducing insects Yellow or orange proved the
most effective colors for this purpose, however these colors may not
complement the plant material and undesirable effects may occur. Another
control measure was to locate the lighting some distance from the main
outdoor living areas

When one source of light was used on shrubs or trees a ﬂat or
two-dimensional effect occurred. To eliminate this ﬂatness and accent
the plant shape, two light sources may be used from different angles or
distances This procedure coincided with that of Quaintance (1939) and
Rodes (1936). Lamps of unequal intensities or different colors were used
to increase the effectiveness by emphasizing plant forms.

Night lighting large public gardens required planning for distant
viewing. Mass lighted areas and the predominate use of white light sources
were most effectively used for this type of lighting.

Outdoor garden lighting was not limited by definite rules. The
best procedure was use of lightweight portable equipment for individual
trial in the garden. This method helped locate the best features and deter-
mine the location, wattage and color of light which gave the best views. By
using portable lighting equipment, permanent location of electrical outlets

and lighting fixtures was reduced to a minimum.

32

A standard neon tube was adopted for lighting the edges of the
ﬂower borders with tubes constructed to fit the border. The neon source
of light provided an over-all illumination; individual accent areas required
additional fixtures for concentrations of light. This light was especially
adopted for silhouette effect behind tall flower spikes and upright plants

A light fixture equipped with ﬂuorescent tubes and a lens to
transmit ultra-violet wave lengths was used for lighting plants. Commer-
cially known as "Black Light", this ultra-violet illumination was used on
plants that had been sprayed with ﬂuorescent paint. A moderate appli-
cation of this paint produced aesthetic lighting. Completely eliminating
visible light, the painted surfaces were illuminated with a brilliant glow
using red color on ﬂowers and green on leaves and stems.

The ﬂuorescent spray painted Chrysanthemum morifolium culti-

 

var Indianapolis Yellow, Spiraea vanhouttei and Taxus media hicksii

 

 

exhibited no harmful growth effects. Keeping quality of sprayed Chrysan—

themum morifolium cultivar Corsair and Dianthus caryophyllus cut flowers

 

 

was not decreased Sprayed Antirrhinum majus and Rosa did not wilt as

 

quickly as those not treated.

33.

SUMMARY

Growth responses of selected plant materials exposed to supple-
mental illumination of various wave lengths was observed. Existing garden
lighting procedures were evaluated and new outdoor lighting techniques
developed.

Selected plants were exposed to additional light of blue, green,
red, white and yellow wave lengths. Plants were grown for one year in a

60°F greenhouse. Zinnia elegans produced greater linear growth and ﬂower

 

size when exposed to supplementary light. Those grown with normal day-

length had greatest ﬂower production. The lighted Chrysanthemum mori-

 

folium plants had greater linear growth and reduced ﬂowering. Additional
light inhibited new shoot development and total stem elongation of Euonymus

vegetus Pelargonium hortorum plants had reduced average ﬂower pro-

 

duction, increased ﬂower stem elongation and greater plant height when

grown under supplementary illumination. Growth of Taxus media hicksii

 

was slightly inhibited by additional light. The growth of Juniperus chinensis

 

columnaris was generally increased by light Supplementary illumination

uniformly increased linear growth of Spiraea vanhouteii

 

To observe frost injury, dormancy and winter hardiness, selected
plants were grown in an outdoor area with additional green, white and yellow

wave lengths of light. No differences were shown in preventing frost injury

34.

by additional illumination. Dormancy and winter hardiness were uniform
for all plants Germination of weed seeds was observed to be inhibited in
the lighted areas.

The night lighting of outdoor gardens showed that concealment
of the light source increased effectiveness of the garden scene. Light fix-
tures were best concealed by plants, metal shields and submerged fixtures
Creating and lighting shadows with color added unusual effects in foundation
plantings. Accenting specimen plants emphasized form and texture in the
night lighted gardens. Flat appearances were eliminated by using two fix-
tures located at different angles. Colored light sources were used to
accentuate plant color, improve appearance of plants, increase winter
beauty of gardens, and reduce attraction of insects. Subtle lighting in large
gardens was not effective for distant viewing. Neon fixtures were used to
illuminate ﬂower borders Fluorescent light sources and ﬂuorescent
paint provided aesthetic garden lighting without harmful effects on plants.
Portable equipment was effective for illuminating the best garden features
and eliminated permanent location of electrical outlets and lighting

fixtures

35.

BIBLIOGRAPHY

Anon. 1935. Painting your garden with lights. Pop. Mech 64: 180-
183.

 

Anon. 1936. Garden lighting sources beautified. Sci. Amer 154:
336.

 

Anon. 1948. Light up. Better Homes and Gard 26: 50-51.

 

Anon. 1954 All outdoors lit up; home gardens. l__.i_f_e 37: 67-69.
Anon. 1954. Shrub lights. 1.39;? Week 1297: 104-105.

Anon. 1955 Outdoor lighting Southern Flor. and Nurseryman (series)

 

Anon. 1956. To light guests to your door Sunset 116: 86-87.

Ashworth, Donna. 1936. Garden magic. Amer. Home 16: 84-86.

 

Bowser, Bernice. 1954 Night life for your garden. Amer. Home 52:
52-53

 

Cooper, Calvin C., and Donald P. Watson. 1952. Inﬂuence of day
length and temperature on the growth of greenhouse violets
Proc Amer. Soc Hort. Sci 59: 549-553.

 

Corey, Paul. 1954 How to install outdoor lights. Pop. Sci 164: 224-
230.

Cutler, C. M., and T. R. LaWall. 1934 Garden lighting brings
magic by night. Good Housekeeping 99: 72-73.

 

Fossum, M. Truman. 1953. Trade in horticultural specialties. U.S
D.A. Marketing Res. Rep. No. 33: 44, 51, 72.

 

Greeves-Carpenter, C. F. 1941. The magic of a lighted garden.
Arts a_n_t_lDec. 54: 18-19.

 

 

Heath, William A. 1938. Lighting the garden Good Housekeeping 107:
60-61.

 

36

Hibben, S G 1940. Lighting municipal gardens. A111. City. 55:109.

Holdson, John H. , and Alex Laurie 1951 The effect of supplementary
illumination on the ﬂowering of the orchid Cattleya triavae.
Proc. Amer Soc. Hort. Sci 57: 379-380. '

 

 

Howland, Joseph E. 1955. Pace setter way to light a garden. House
Beautiful 97: 142-145.

Keyes, C. G. 1939. Bud formation, abscission, and ﬂower production
of gardenia as affected by light and temperature Proc. Amer.
ﬂ Hort S_ci 37: 1034-1036.

 

Kroscher, Ralph M. 1933. Garden lighting. _A_m_. Phot 27: 472-476

Laurie, Alex. 1930. Photoperiodism--practical application to greenhouse
culture Proc. Amer. Soc. Hort. Sci. 27: 319-322.

 

 

Lin, Lok-Chien, and DonaldP. Watson. 1950. The inﬂuence of daylength
and temperature on the growth and ﬂowering of Callistephus
chinensis Nees. Proc. Amer. Soc. Hort. Sci. 55: 441-446.

 

 

 

 

Person, Charles. 1932. Gardens that bloom in the night. 3‘2 Mech.
58: 328-330

Piringer, A A., and Neil W. Stuart. 1955. Responses of hydrangea to
photoperiod. Proc. Amer Soc. Hort Sci. 65: 446-454.

 

 

Poesch, G. H. 1931 Forcing plants with artificial light. Proc. Amer
Soc Hort. Sci. 28:402-406.

 

 

Poesch, G. H. 1935. Supplementary illumination from mazda, mercury
and neon lamps on some greenhouse plants. Proc. Amer. Soc.
Hort. §c_i_. 33:637-638.

 

 

 

Poesch, G H. 1936. Prolonging the ﬂowering period of Chrysanthemums
with the use of supplementary illumination. Proc. Amer Soc.
Hort. §_c_i_. 34: 624-626.

 

 

 

Polster, Edythe, and Myrtle Fahsbender. 1954. Garden lighting.
Pilgrim Press Corp.

37.

Post, Kenneth. 1942. Effects of daylength and temperature on growth
and ﬂowering of some ﬂorist crops. Cornell Univ. Agr. Exp.
.83.:- all 787-

 

 

Post, Kenneth 1948. Daylength and flower bud development in Chrysan-
themums. Proc. Amer. Soc Hort. Sci 51: 590-592

 

 

Post, Kenneth. 1950. Controlled photoperiod and spray formation of
Chrysanthemums. Proc Amer Soc. Hort. Sci 55: 467-472

 

Quaintance, Ethel. 1939. Making garden moonlight Better Homes and
Gard 17:110-111.

 

 

Rebhar, John R. 1955 Garden lighting Flower Grower 42: 82-85

 

Rodes, Marjorie Reed. 1936 Lighting to make the garden more color-
ful at night. House and Card 69: 32-33.

 

Stern, Gladys Gillies. 1954. Report of the month. Flower Grower 41:
10. '

 

Toland, Helen. 1934. A step in the light direction. Amer Home 12:
144-145.

 

Vince, Daphne 1956. Studies on the effects of light quality on the growth
and development of plants. Jour Hort Sci 31: 16-24

 

Warren, Dean. 1937. And so into the night Better Homes and Card
15: 54-55.

 

Withrow, Alice P., andR B. Withrow. 1947. Comparison of various
lamp sources for increasing growth of greenhouse crops
Proc Amer Soc. Hort Sci. 49: 363-366.

 

Withrow, R. B., and H. M. Benedict. 1936. Photoperiodic responses of
certain greenhouse annuals as inﬂuenced by intensity and wave-
length of artificial light used to lengthen the daylight period.
_P_l_a_tlt Rhys 11: 228-249.

ASPECTS OF NIGHT LIGHTING IN THE GARDEN

By

CHARLES CLAYTON FISCHER

AN ABSTRACT
Submitted to the School for Advanced Graduate Studies of Michigan
State University of Agriculture and Applied Science
in partial fulfillment of the requirements

for the degree of

MASTER OF SCIENCE

Department of Horticulture

1956

Approved SIS-“MM ? DO (LII/:43“

CHARLES CLAYTON FISCHER ABSTRACT

Growth responses of selected plant materials exposed to supple-
mental illumination of various wave lengths was observed. Existing garden
lighting procedures were evaluated and new outdoor lighting techniques
developed.

Selected plants were exposed to additional light of blue, green,
red, white and yellow wave lengths. Plants were grown for one year in a

60°F greenhouse. Zinnia elegans produced greater linear growth and

 

ﬂower size when exposed to supplementary light. Those grown with nor-

mal daylength had greatest ﬂower production. The lighted Chrysanthemum

 

morifolium plants had greater linear growth and reduced ﬂowering. Addi-
tional light inhibited new shoot development and total stem elongation of

Euonymus vegetus. Pelarggnium hortorum plants had reduced average

 

ﬂower production, increased ﬂower stem elongation and greater plant

height when grown under supplementary illumination Growth of Taxus

 

media hicksii was slightly inhibited by additional light. The growth of

 

Juniperus chinensis columnaris was generally increased by light. Supple-

 

mentary illumination uniformly increased linear growth of Spiraea van-

 

houteii.

 

To observe frost injury, dormancy and winter hardiness, sel-

ected plants were grown in an outdoor area with additional green, white

ABSTRACT - 2

and yellow wave lengths of light No differences were shown in prevent-
ing frost injury by additional illumination. Dormancy and winter hardi-
ness were uniform for all plants. Germination of weed seeds was observed
to be inhibited in the lighted areas

The night lighting of outdoor gardens showed that concealment
of the light source increased effectiveness of the garden scene Light
fixtures were best concealed by plants, metal shields and submerged
fixtures Creating and lighting shadows with color added unusual effects
in foundation plantings Accenting specimen plants emphasized form and
texture in the night lighted gardens. Flat appearances were eliminated
by using two fixtures located at different angles. Colored light sources
were used to accentuate plant color, improve appearance of plants, in-
crease winter beauty of gardens, and reduce attraction of insects. Subtle
lighting in large gardens was not effective for distant viewing. Neon
fixtures were used to illuminate ﬂower borders FluoresEent light sources

\, ..
and ﬂuorescent paint provided aesthetic garden lighting‘without ha\rmful

\ .

.pﬁ

effects on plants. Portable equipment was effective foiilluminat-ing the

.‘E .ﬁ- \
best garden features and eliminated permanent location of electrical out -._

‘

.. \

lets and lighting fixtures
Accompanied by three colored figures, two black and white

figures and five tables.

 

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Demco-293