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Canadians growing their own food generally start their seedlings indoors in March, but for early birds and those on the west coast, indoor growing starts in February. We do this to get a head start on the season, but also, because the growing season of many hot crops is too long to be able to simply plant their seed in the soil and wait for harvest. Spring and fall frost dates limit our growing season in the Far North. So we adapt and grow indoors, or buy our transplants in April, May and June to plant in our gardens then.

The Urban Edible Gardening Guidebook

Seedling with 20%, 10% and 0% added worm castings

Chris MacLuckie

The indoor seeding area can be a simple affair against a south facing window. If there is 8 hours of sun per day, this can work. The window area should not get too cold during the night. Covers for trays can be used to keep the heat in at night.


If there is not enough natural sun, then don’t grow your seedlings without some strong grow lights. Buy inexpensive T12 fluorescents or even LED’s, they both use little electricity. Set them on a timer. Give your seedlings the best possible start. Spindly, weak seedlings are avoidable. They invite disease and bugs as soon as they are transplanted into the garden.


To hold the seedlings egg cartons can be reused, or plug or open flat trays can be purchased and reused for several seasons. Bigger operations use soil blocks devices which use a form to create wall-less soil blocks. My preference is for open flats, but it’s subjective.


5000 Miles of Hope

Soil mix should be light, fine yet rich. It should not crust or congeal under any circumstances. It should drain well. An amended peat or loam mix works well. Grow mix or potting mix can be amended with up to 1/3 finished compost or weed seed free triple mix. I also like to add a little bit of alfalfa and kelp meal. If a standard grow/potting mix is used on its own, the seedlings will need to be potted on or moved to a new container as soon as 3 weeks after germinating as the potting mixes are meant for quick establishment, not long term nourishment. They were historically supplemented with chemical fertilizers. Rather than using those, try the worm castings/ compost or weed seed free triple mix.

To keep water in the bottom of the tray and encourage root growth, double trays can be used, with the bottom one being solid, the top one perforated. Water into the bottom tray. Don’t use super cold water and let your water sit for a day or 2 if it is chlorinated or treated. When watered this way, the leaves can be misted with a spray bottle. This allows for even moisture throughout the soil mix, but a little moister at the bottom.


Many seeds are annoyingly small – how do you get just one where you want it? This is one of the reasons I use open flats, 11” by 22”. I make 8 to 11 furrows in the short side with a knife. I then grab some seeds in between my thumb and index finger and roll them out into the rows. Some of them bounce out. I don’t care. I plant about double to triple the seeds I need for the spacing and thin them out later. Unless the seed is expensive, then I space them out more carefully. Once the seeds are in the rows I immediately put a ID marker in the flat and write down the amount of rows with which seed in my journal. I then cover the seeds with the soil from either side of the furrow. I usually start 3-4 flats at a time.

Instead of using covers for each one, I lay each one on top of the other – DIAGONALLY. This preserves moisture but doesn’t compress the soil. Of course, the trays with the slowest germination are placed at the bottom. Lift the trays starting 3 days before expected germination date to see if any are coming up. Once the seeds peak out, immediately put them under intense sunlight or grow lights at up to 16 hrs per day. The clear tray cover can be placed on top, but I recommend only half of the day, or at night.

From the period of seeding until germination, and for 2 weeks afterwards, seedling trays should never be waterlogged. This would create the ideal environment for damping off, the phenomena where seedling stalks rot out and die. For the first week especially, err on the dryer side.

Strong fans should be set on oscillating mode when the seedlings are 10 days old. We are going to simulate outdoor conditions. When the outside temps are nice during the day, trays can be put outside for 4-8 hours per day, and brought inside at night. For the final week or 2 before transplanting, the seedlings can be left outdoors 24/7, in a warm protected area at night.

When the seedlings are 2-3 weeks old, they can be thinned to the desired spacing. If the seedlings are to be potted on to another larger pot after 6 weeks or so, then a tighter spacing can be used until then.

If using open flats, seedlings are prepped for potting on or transplanting by knifing slits in between rows 7 and 2 days beforehand. This stimulates new root growth and makes it easier to move the bareroot transplants. When potting on or transplant, a transplant bath can be used to help with the shock of moving to a new home. The transplant bath is an amended compost slurry which the seedlings roots are dipped into.

Items needed for indoor seed starting:

  • Seeds
  • Light
  • Soil mix
  • Containers
  • Water
  • ID tags
  • Journal

A careful, tending hand


Order my Edible Gardening Guidebook here:




www.amazon.com .ca .eu  search “Edible Gardening”



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