How to Transplant Seedlings

Water your seedlings thoroughly and handle them gently. Then, follow these steps to help your seedlings make the transition to the garden iwht minimal disruption.

Unfortunately, when you move seedlings outdoors, there’s a chance they 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 two days and then give filtered sun or half-day sun for two days. After that, they should be ready for bright light. Below we’ve mapped out additional care tips to follow after transplanting your seedlings from indoors to outdoors.

Growing On

Growing seeds on to garden size plants may take only a week or it may take several months, depending on the species. Your seed packet instructions and the Park Seed Catalog’s Cultural Index give detailed information about each type of plant, including how long the seeds take to germinate and how long until your vegetable seeds will yield produce, or your flowers will be in bloom. The easiest way to provide for your seedlings is to start them in a seed starter kit under a grow light.

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 watering (lower layers of soil should still never dry out). Feed once a week using a water-soluble fertilizer.

If you've planted more than one seed in the starting plug and both have germianted, you may need to thin them. Thinning allows the strongest of the seedlings to mature and use the soil nutrients and water without competition. Watch this video on thinning from Carrie with From Seed to Spoon, Park Seed's growing app that will calculate dates for gardening activities based on your location.

Pinching

If you started flower seeds that form a bushy shape, you may have to pinch them back. Leave plenty of foliage and some branches so growth can continue, but pinch off just above a leaf or branch. A small pair of pruning shears does a better job than fingers. The plant will then send out shoots from the stem and increase the fullness of your plant.

Setting Out

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.

Plant Condition

Plants are definitely ready for the garden when roots grow through the bottoms of their containers, but you can hold most types up to four more weeks before planting. If you must wait for ideal planting weather, you may have to move the plant into a larger size pot, so it doesn’t become root-bound. While each type is different, a good rule of thumb is to set plants out when the seedling has two to four sets of true leaves. Plants for container gardens should be set out at this same stage.

Hardening Off

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. You can help prepare the plants by running a tabletop fan on them while they are indoors to simulate the wind or just gently run your hand over the tops of the plants when you check on them. This will encourage your plants to grow a stronger stem.

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 them back indoors each evening.

After two days, leaves and stems should be stronger. Move transplants to a half-sun location for two 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.

Planting Outdoors

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. We recommend doing this in small groups so your plants don’t wilt before you plant them. Space them 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 habits, 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.

Watering In

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.

Mulching

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 and 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.

Follow these helpful steps when transplanting your seedlings for optimal growth and life.