If plants have not been seeded in individual containers, they must be potted up (a.k.a. “pricking out” or “transplanting up”) into a larger individual container to give them proper growing space. One of the most common mistakes gardeners make is leaving seedlings in the seed flat too long. The ideal time to transplant young seedlings is when they are small and there is little danger of setback from root shock. This is usually about the time the first “true leaves” appear above or between the cotyledon leaves (the cotyledons or “seed leaves” are the first leaves to appear).
Photos of plants with seed leaves and true leaves
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- Soil-less mixes contain a small amount of added soluble nutrients. If your transplants are to be grown for more than 6 weeks you may need to fertilize with a soluble fertilizer. Follow label directions for indoor plants or transplants.
- Wash off any liquid fertilizer that contacts foliage. Young seedlings are easily damaged by too much fertilizer, especially if they are under any moisture stress.
- A high-quality screened compost can be mixed 50-50 with a soil-less mix to grow transplants. The compost provides additional nutrients.
- Commercially available containers such as peat pots, plastic pots or cell packs make the best use of space as they fit close together in trays.
Recommended individual cell sizes:
- Tomato, pepper, and eggplant transplants- 3-4 in. square
- Squash, cucumber, broccoli, and cabbage- 2-3 in. square
- Lettuce, beets, spinach, kale, and other greens- 1-2 in. square
- Peat pots can be planted directly into the garden. Be careful to cover the pot completely with garden soil. If the top edge of the peat pot extends above the soil level, it may act as a wick and draw water away from the soil in the pot. To avoid this, tear off the top lip and bottom of the pot and then plant flush with the soil level.
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| Broccoli raab seedling ready for transplant | Broccoli raab seedling after transplant |
- Carefully dig up the small plants with from the seedling flat or container using a butter knife or wooden plant label and gently ease them apart in small groups to make it easier to separate individual plants. Avoid tearing roots in the process.
- Handle small seedlings by their leaves, not their delicate stems.
- Make a hole in the medium into which the seedling will be planted. Set the seedlings so that the leaves and growing point are only slightly above the soil line (most of the stem can be buried).
- Firm the media around each plant and water gently.
- Continue to light them for 14-16 hours per day, keeping the tops of the transplants 1-2 in. from the tubes.
- Gently brushing the tops of your transplants with your hand or wooden stick will help control their height and increase stockiness. Ideal transplants are as wide as they are high.
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These tomato seedlings have outgrown the containers and must be transplanted into larger containers until time to plant outside |
ShareThisFor more information, contact Jon Traunfeld
Last updated: 03/1/2011