Young ornamental plants and herbs are propagated from seeds and unrooted cuttings in greenhouses. Previous research has determined that the photosynthetic daily light integral (DLI) and air average daily temperature (ADT) set point should be 030310 mol·m-2·d-1 and 030324 °C, respectively, for most ornamental plants. However, young plant recommendations are lacking for air ADT and root-zone heating (RZH) set points for cold-tolerant crops, appropriate DLIs for herbs, and the minimum duration of far-red (FR) radiation needed during the seedling stage to induce long-day plants (LDPs) into flower. Therefore, our objectives were to 1) determine if cold-tolerant crops can be rooted at a lower air ADT with RZH, 2) quantify how DLI influences rooting of herb cuttings, and 3) determine the minimum duration of supplemental lighting (SL) providing FR radiation during seedling production to hasten subsequent time to flower of LDPs. High-quality calibrachoa, nemesia, nepeta, and osteospermum rooted cuttings were produced at an air ADT and RZH temperature of 16 and 24 °C, respectively, while campanula, petunia, and phlox were successfully propagated at an air ADT and RZH set points of 16 and 21 °C and 21 and 27 °C, respectively. A DLI of 10 to 12 mol·m-2·d-1 produced high-quality liners of oregano, rosemary, sage, spearmint, and thyme. Seedlings of calibrachoa, petunia, and snapdragon were taller when grown under FR SL for 226514 d and subsequent flowering was hastened by 3 to 8 d under FR SL for 28 to 35 d compared to seedlings under high-pressure sodium lamps for 28 to 35 d. These results provide further insight for greenhouse growers that want to produce high-quality liners and seedlings without sacrificing finish plant quality.
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