A seedy proposition

Planting Mixes
The mix recommended for starting many seeds is actually a combination of sterile, finely ground peat moss and vermiculite that contains no nutrients. It's ideal for most small seeds that will eventually be transplanted to larger containers. You can keep seedlings in the sterile starter mix until they're ready to go outside, but if you do, you'll need to fertilize them more intensively than if you had transplanted them to potting soil. (Don't use garden soil. It can be contaminated with weed seeds and disease spores.)

If you prefer to keep seedlings in one container until they're ready for the garden, you can purchase a mix of peat moss and sterile soil that's labelled as suitable for seed starting. It contains some nutrients seedlings will need during their indoor life.

It's difficult to moisten seed starter mix with regular watering, so always dampen it before sowing. (Use one part water to four parts soil.) Put some mix into a clean plastic pail, add warm tap water and stir well. Wait several hours for the water to be absorbed. The mix should feel like a squeezed-out sponge - damp but not wet - when ready.

Seedling Care
Fill each container with the mix, then tamp the top but don't pack down hard; the mix should settle about six millimetres below the rim. Follow directions on the back of the seed packet. Most seeds do well between 18°C and 21°C. Sow seeds in properly moistened mix, then cover each flat with its plastic dome to keep seeds moist enough to germinate; set flats under lights. Check regularly; do not allow seeds to dry out.

Seeds that need light to germinate should not be covered with soil mix. For those that need darkness, cover the flat with a piece of cardboard or newspaper. All seeds need light as soon as they sprout so check them daily: some spring to life in less than a week, while others take several weeks. After germination, remove the plastic domes to prevent seedlings from succumbing to disease due to excess humidity. To raise healthy seedlings, adjust the lights, always keeping the tubes five to 7.5 centimetres above the seedlings to prevent their stems from stretching and weakening. If seedlings at the outer edges lean in toward the light, reflect more light toward them by taping a length of aluminum foil along each side of the fixture. Rotate cell packs periodically so all seedlings get even light.

Check trays daily for moisture, but don't overwater. Before a seedling develops its first true leaf, it develops two cotyledons, or seed leaves, which contain stored food that gives the plant its start. Once the true leaves appear, feed seedlings weekly with a water-soluble houseplant fertilizer, such as 15-30-15 or 20-20-20, applied at half strength.

Hardening Off
Plants grown indoors need time to adjust to the rigors of outdoor life. A week before transplanting to the garden, set flats outdoors in a sheltered, shady area, such as the north side of your house, first for half a day, then for longer periods, gradually moving them to sunnier, windier areas. For the first few days, bring them inside at night or cover them with an old blanket supported by overturned pots or cement blocks, then leave them outside overnight uncovered. Cold-tolerant plants, such as pansies and cabbages, should be hardened off about a month before tender heat-loving ones, such as peppers and tomatoes.

Building an Indoor Plant Stand
To start building your plant stand download the pattern by clicking here. (PDF format requires free Adobe Acrobat Reader)

Plant stand designed by Ken Balcer, Sandi Construction, Oakville, Ont. Diagrams by Vicky Elsom.