Seedlings may droop or wilt somewhat right after transplanting, if some roots were broken or disturbed. To speed recovery, keep them quite moist and out of the sun for 2 days, then give filtered sun or half-day sun for 2 days, after which they should be ready for bright light.
Growing on to garden size plants may take only a week or it may take several months, depending on species. Your seed packet instructions and the Park Seed Catalog’s Cultural Index give detailed information about each type of plant.
Watering and Feeding
After seedlings are established, with healthy roots spreading through the grow mix, they will need a drier medium and less frequent, but more concentrated feedings. Let the surface of the grow mix become dry to the touch between waterings (lower layers should still never dry out). Feed once a week using a water soluble fertilizer.
If plants get too tall before planting time, pinch them back. Leave plenty of foliage and some branches so growth can continue, but pinch off just above a lower leaf or branch (see diagram below). A small pair of pruning shears does a better job than fingers.
It’s best to set your transplants out before they begin to bloom, since a young garden plant needs its energy to grow roots, not flowers. If your transplants set flower buds or bloom before planting out time, disbud them or cut off the blooms.
Plants are definitely ready for the garden when roots grow through the bottoms of their containers, but you can hold most types up to 4 more weeks before planting, if you must wait for ideal planting weather. While each type is different, a good rule of thumb is to set plants out when 2 to 4 inches tall. Plants for container gardens should be set out at this same stage.
Transplants that have been raised indoors are soft, and must get used to sun, wind and rain. It is best to let them "harden off" gradually for several days before planting in the garden.
Move the trays of transplants outdoors to a sheltered, shady place out of the wind. Keep them well-watered. (If they wilt anyway, bring them back inside until they perk up again.) Bring back indoors each evening.
After two days, leaves and stems should be stronger. Move transplants to a half-sun location for 2 more days. When they are tough enough to go through the day without wilting, it’s time to plant them in the garden or container.
Your transplants will grow best and reward you the most if they are set out into well-prepared garden soil. If your soil needs fertilizer or pH correction, take care of these tasks before you turn or rake the soil for the last time.
Before planting, smooth the surface of your bed with a garden rake. Level out any depressions and remove hard clods, rocks and sticks.
To get proper spacing, place your transplants on the surface of the garden bed in an arrangement that pleases you. DO THIS IN SMALL GROUPS . . . YOU DON’T WANT PLANTS TO WILT BEFORE YOU CAN PLANT THEM! Space far enough apart so that each plant can grow to maturity without overcrowding its neighbor. Some plants need more space than others; your catalog and packet instructions recommend optimum spacing.
Some plants, especially those with base branching habit, do not like to have their stems buried. These include: Gerbera, Gazania, Pansy, Petunia, Primula, Salvia, Zinnia, Ageratum, Begonia, Cabbage, Lettuce, Pepper and others.
Other species, such as Marigolds, Chrysanthemums, Coleus, Cosmos, Impatiens, and Tomatoes do not mind if the lower part of their stems is buried, and will root readily along the buried portion of the stem.
Do not bury leaves. If you do plant part of the stem underground, remove the leaves from that part of the stem first.
Avoid planting any debris such as sticks or leaves along with the root system of your plants. Such debris interferes with the necessary contact between root and soil.
If your plants are set out closely in beds, soak the beds immediately after planting. Soil should be wet to a depth of several inches below the roots. Run a gentle sprinkler or soaker hose as long as it takes to achieve this. Plants that are set out individually should be watered so thoroughly that a temporary mud puddle forms around the base of each plant. This will eliminate air pockets and bring about good root/soil contact. Avoid splashing soil onto the stem or leaves of your young plants. For this reason, it’s best to avoid having water from your hose flowing at full force. Plants should be watered early enough in the day so that they do not go into the night with wet leaves.
Mulch your beds as soon as you have planted and watered. Use material that has weathered for several months so as not to deprive the soil of nitrogen. This may happen with the application of fresh organic material which has not weathered. Old leaves, bark, dry grass clippings, wood shavings or any other loose, light material will do. Spread mulch several inches deep over the soil between the plants, press the mulch gently around the base of the stems, taking care not to break the stems or bury the leaves. Proper mulching will conserve moisture and help keep down weeds.