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| Scheduling annuals bedding plants | |
| It is important for producers of annual bedding plants to program production in order to meet the requirements of retail customers or to attempt to accomodate unseasonal weather and unexpected changes in demand. Seed raised plants must first pass from the juvenile to mature stage of growth before environmental conditions can induce flowering. This period of transition varies between species but it is usually during the first month after germination for annuals. It can extend to 3-6 months for herbaceous perennials. The mature stage can be measured by the number of nodes developed on the main stem. Researchers at the University of Minnesota and Michigan State University have determined three factors that can be determined for for each given species , to help schedule the flowering of annual bedding plants, also taking into account the amount of PAR (photosynthetically active light) plants are receiving during the day. The first factor is ‘response groups’. This is the time taken for conditions to induce flowering of mature plants grown at a constant 20°C day. The second factor is ‘growth time’. In a seed raised crop this is the time it takes from germination until flowering under conditons that induce flowering at a constant 20°C. The research has determined the growth time for more than 50 types of bedding plants in association with seed companies and commercial growers. The third factor is ‘time to re-flower’. This refers to plants grown from rooted or unrooted cuttings. This is the time it takes from pinching a cutting until the first flower opens on the shoot that arises after the pinch, at a constant temperature of 20°C. Cutting material is usually already mature. Using these three factors it is possible to establish development tracks for each given crop. It allows a grower to know whether a crop is ahead or behind schedule. It can also assists growers to slow down or speed up a crop according to changes in consumer demand. “Greenhouse Product News” For further information: John Erwin, University of Minnesota, E-mail: erwin001@umn.edu www.florifacts.umn.edu/ and Eeik Runkle, E-mail: runkleer@msu.edu www.hrt.msu.edu/erik-runkle/ |
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