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How to sow and transplant tomatoes.

The cultivation of tomatoes
Published on 05/03/2021

Tomato planting time is approaching!

When, how, with what, do your sowing???

If you're like me, you can't wait to get your hands dirty and watch your tomato plants grow. I explain here how to sow and transplant tomatoes.

Equipment required to plant your seeds, without ruining yourself:

Good quality tomato seeds, a marker and tags or wooden sticks to identify your seedlings, soil for seedlings, preferably approved for organic cultivation, containers recovered or purchased, something to gently water your seedlings, a fan to circulate air in the room, an auxiliary lighting system and ideally a timer, gloves if you don't want to get your fingers dirty!

You can use recovered containers, well cleaned with soapy water. Make small holes in the bottom so that excess water can flow out.

You can also buy pots of different sizes and multi-cell containers.

For watering, a salvaged bottle with holes in the cap works great. Otherwise use a sprayer at first and then a small watering can.

Fluorescent hanging lamps (Cool White tubes) can do the trick very well. Later, you can add Warm White tubes for flowering. But if you start your seedlings at the recommended time, you won't need it. You can also equip yourself with an LED system, but the subject will be covered in a future article.

When to sow tomatoes?

It is recommended to sow tomatoes 6-8 weeks before the last expected frost in your hardiness zone. It is best to transplant outdoors after the date without risk of frost. Typically this is 2 weeks after the last expected frost date. To find your hardiness zone, click on the link and in the menu, enter the first letter of your city or the nearest one listed. http://planthardiness.gc.ca/index.pl?m=22&lang=fr&prov=Quebec&val=A

How to make tomato seedlings:

Start by moistening the soil well before filling your containers.

Now you have two options:

- Either make holes one centimeter deep with a pencil, a skewer or other tool at your convenience, in the soil and place a seed in each hole, then cover with soil.

-Either place the seeds on the surface and cover everything with a centimeter of potting soil.

Do not forget to space your seeds well, one or two centimeters, to be able to separate them more easily when transplanting.

Lightly tamp the soil and water gently to release small air pockets in the soil.

You can cover with a bell jar, plastic wrap or make sure to keep moist.

Place the pots in the heat between 20-25°C.

Water regularly to maintain humidity. Beware of damping off if you cover the container, remove the cover as soon as the seedlings show up!

Identify the varieties, memory is a faculty that forgets!


Place hanging fluorescent lamps as close to the plants as possible (3-5 cm above them). Adjust them as the plants grow.

Leave them on for 14-18 hours a day. So if you don't have a timer, turn them on when you wake up and turn them off just before you go to bed.

You can also opt to purchase a programmable timer.


Now that the cotyledons and the first true leaves have appeared, it's time to transplant the seedlings.

Start with a first deep watering so that the seedlings do not lack water and are easier to separate.

Then, prepare your pots by putting moist potting soil up to a third of the pot, watering.

Take the seedlings out of the container, using a fork or chopstick to help you. Or by pressing the bottom of the container to release the clod of earth.

Gently separate the seedlings, cut the cotyledons. The cotyledons are the first leaves produced by the plant. Often they end up falling off. Removing them allows you to transplant deeper.

Make a hole in the soil just deep enough to bury the stem down to the first true leaves. Place your seedling at the bottom.

Adjust the depth of the hole as needed.

Put potting soil around the stem and gently tamp it down.

Water deeply. Don't worry if there is soil on the leaves, it will come off with watering or by blowing on it when the leaves are dry.


In the beginning, water regularly, remember that the roots take some time to settle in the pot.

Then, start to space out the waterings, letting the soil dry out to get the plant used to outdoor conditions. If the leaves are getting soft and the soil is dry, it's high time to water.

Do not worry! Like everyone else, I also forget to water or be a little late to do it.


The plants will grow and will most likely need a second transplant, to avoid root curling in the pot.

Proceed in the same way, in larger pots with compost enriched soil and add a little perlite or potting soil, removing the first true leaves instead of the cotyledons.

Don't forget to properly identify your varieties!

I will soon discuss the acclimatization of plants before transplanting to the garden. After all this work, we must be very careful not to kill our plants, by putting them outside too quickly without acclimatizing them.

Happy gardening!

  • The cultivation of tomatoes