You've sown some perennial seeds in a container and now they've germinated---a tight cluster of tiny seedlings. When and how do you separate them? And then, are you worried about moving the vulnerable young plants outside?
The process isn't as harrowing as it may seem. Panayoti Kelaidis of the Denver Botanic Gardens shows how to prepare indoor-grown perennial seedlings for their new life in the great outdoors. Even when he's transplanting temperamental poppy seedlings, he usually has a near-100% success rate with this method:
Materials
- builder's sand
- soil mix (perlite / peat)
- permanent pen
- labels
- gravel
The perfect time to separate the seedlings into separate pots is when two or three true leaves have formed. The best pots to use are square, 2-1/2-inch plastic pots; you can fit 32 such pots into a flat.
- First, select a peat or perlite soil mix and add a little builder's sand (or other type of sandy gravel) to encourage drainage and give the mix some structure.
- Fill the individual pots with the mix.
- Next, gently tease the seedlings apart. Holding each by the leaves (not by the roots), drop the seedling into a hole you've poiked in the soil mix in each pot. After transplanting all the seedlings, top each pot with a little gravel to help keep the soil cool.
- While transplanting, keep the young plants out of direct sun (or transplant them on a cool, rainy day). Label the flat with the plant name.
- To water the plants the first time, set the flat in a large container, such as a children's swimming pool, with water in the bottom--the water can reach up to a half-inch below the top edge of the flat. After the initial watering, the plants can be watered from the top.
- Nourish the plants with fertilizer diluted to half strength to avoid burning.
- To effectively "harden off" the transplants before moving them to the garden, place the flat on the north side of a building, out of the sun. It may be necessary to protect the plants with a shade cloth, since young plants are especially vulnerable to burning.
- Water the plants daily, twice daily if necessary. Then move them to the garden after they've grown to several inches tall (with poppies, it generally take about three to four months to grow out a seedling to a transplant large enough to thrive in the garden).
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