In gardening, a transplant is a plant that is moved from one location to another location. For northern gardens, where the growing season is limited by spring and fall frosts, some plants must be germinated and grown into small plants indoors before they are planted outdoors. This extra growing period allows the plants to get a ‘head start’ on the growing season so that once they are placed outdoors, they will flower and/or mature during the relatively short growing season.
Growing your own transplants? Now is the time to start. For successful transplant production you will require: clean, smaller containers with drainage holes in the bottom that are 5-10 cm in diameter, depending on how big of a transplant you intend to grow; potting soil for growing indoors (a peatmoss based seedling mix with perlite and vermiculite is ideal); a warm (22ËšC), sunny location for growing your seedlings; supplemental grow lights are preferred as even a south facing window can provide a challenge for growing good quality transplants; 20-20-20 soluble fertilize that will be applied weekly (mix according to label directions) and clean water at room temperature for watering plants.
Vegetables that must be transplanted to mature during a northern growing season include celery, leeks, peppers, tomatoes, okra, Spanish onions, brussel sprouts, eggplant, cantaloupe, watermelon, and okra. Celery, leeks and Spanish onions are slow to germinate and grow; they should be started 10-12 weeks before planting out in spring. Peppers require eight to 10 weeks 'head start', while tomatoes, okra, eggplant and brussels sprouts should be started six to eight weeks before planting out. Never use garden soil to grow your indoor transplants in containers. Garden soil does not drain properly in containers and can be a source of insects and diseases.
Cantaloupe and watermelon transplants should only be started 10 days before transplanting out. Although cantaloupe and watermelon need to be transplanted to produce mature fruit, they do not like to have their roots disturbed: it is very important to minimize handling the roots when transplanting. Cucumbers, pumpkins and winter squash do not need to be transplanted but can benefit from it. Seeding these vine vegetables into a Jiffy 7 peat pellet and planting that pellet directly into the soil will minimize root damage. Before seeding, the flat Jiffy 7 discs are soaked in warm water. The flattened 5mm disc will suddenly expand into a 4cm cylinder surrounded by biodegradable netting, which will allow roots to pass through as they grow. When transplanting out into the soil, the entire Jiffy 7 peat pellet must be covered with soil, as pellets that are not covered will dry out quickly, drawing water away from the transplant. The vine vegetable transplants will be young, only exhibiting one or two true leaves besides the cotyledons. Unlike vine seedlings, transplants that require 6-12 weeks to grow (i.e. celery leeks, peppers, tomatoes, etc) should have at least 3-4 sets of true leaves with a strong, healthy root system. Healthy transplant roots should be white: tan or brown colored roots may indicate a root rot problem.
Some vegetables benefit from transplanting to avoid intense insect pressures that may decimate young, tiny seedlings. Brassica vegetables such as broccoli, cauliflower, cabbage and kohlrabi are examples of these. Although the length of the growing season does not warrant transplanting, the tiny seedlings that emerge from direct-seeded brassica plants outdoors can be easily destroyed by flea beetles early in spring. Start brassica transplants indoors 6 weeks before planting out.
Many herbs benefit from transplanting out. Some herbs have very small seeds that require ideal growing conditions to germinate quickly and successfully: basil, marjoram, oregano, sage, and thyme are examples of small-seeded herbs. Other herbs are slow growing, and by the time they would reach a usable size, the gardening season would be nearly over. For best results, start herbs indoors eight to 10 weeks before transplanting out. Dill and coriander are the exceptions; they are fast-growing and do not require transplanting. Most herb seeds are quite small; cover them lightly and do not allow the soil surface to dry out during germination.
Most annual flowers should be started indoors eight to 10 weeks before planting out. Always check with the seed package as to whether the seed requires light to germinate: usually, the smaller the seed, the more likely light is required for germination, or the flower seed should only be lightly covered. Zinnias, marigolds, sweet peas, calendula, morning glory, nasturtiums, celosia and cosmos can be direct-seeded in the garden in mid-late May and will start blooming by early-mid July.
Are your transplants stretched out and ‘leggy’? A healthy transplant has a strong stem with short internodes: internodes are the length of the stem between leaves. Whereas professional greenhouse growers have chemicals to spray to reduce the height of their transplants, a home grower does not have that option. Avoid leggy plants by providing ample space and adequate light for your seedlings to grow. Strengthen transplants stems by setting up an oscillating fan for six to eight hours/day or lightly brushing the tops of your plants daily with a towel or stick to help control transplant height and increase stem girth.
This column is provided courtesy of the Saskatchewan Perennial Society (SPS; [email protected]). Check our website (www.saskperennial.ca) or Facebook page (www.facebook.com/saskperennial) for a list of upcoming gardening events.
