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Seeding 101

Basil seedlings (Ocimum basilicum)
Photo: Jardin botanique de Montréal (Lise Servant)
Basil seedlings (Ocimum basilicum)

Here is what you need to know when starting indoor seeding, whether you want to grow vegetables or annuals.


Normal house lighting, at an intensity 10 to 100 times lower than outside, is often insufficient for seedlings. Two to four 40-watt fluorescent lights (120 cm), placed about 15 to 30 cm above the seedlings and left on 12 to 14 hours per day will provide all the light required. If extra lighting is not feasible, seedlings should be placed as close as possible to a window with a south or west exposure as soon as they sprout.


A temperature of 21 to 24°C will ensure that the seeds germinate well. However, after the plants have sprouted, the ideal temperature should be lowered to 18°C in daytime and 15°C at night. Too much heat, combined with insufficient light, will inevitably produce weak and spindly plants.


Seedlings can be potted in a great variety of containers, such as styrofoam or fibre trays and pressed peat or plastic pots. You can even find containers filled with the right soil, at seed shops. In all cases, the containers should be clean so that fungal diseases don't develop.


Vermiculite and mixes for seedlings with a peat moss base give better results than soil mixes. They are light, porous and retain moisture well. Adding fertilizer to the mix is not required during the first few weeks. It is advisable to moisten the peat moss mix before using it. From then on, it should be kept damp but not saturated.

For seedling species that do not have to be thinned out, such as onions and leeks, the same subsoil can be used, as long as a fertilizer is added. Onion and leek plants can be trimmed by a third, with a pair of scissors, if they become too long.

Choice of seeds

The quality and yield of vegetables or flowers will depend in large part on your choice of seeds. Every year, seed shops offer hundreds of varieties of vegetables and annuals for amateur gardeners. How does one decide which seeds to choose? Gardening books and local seed catalogues will give you a good idea. First-time gardeners should determine how much space they have as well as personal needs and tastes.

New varieties or hybrids often have several advantages. These seeds can be sturdier, more precocious, more productive or more resistant to disease, depending on the type. Leftover seeds can be stored in a hermetically sealed container in a dark, dry place. It is generally recommended to use fresh seeds each year, however.

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