Growing from seed

(Question)

I started growing plants from seed about four weeks ago. The plants are now getting very large. I seeded tomatoes, zucchini, green and yellow beans, zinnia, marigolds and nasturtium. They are very leggy, did I start too early as the weather is still cold. By the way I am trying to harden the stalk by moving outdoors during the day. Thank you

(Answer)

Thank you for contacting Toronto Master Gardeners.

You’re right, timing is very important. You should base all of your plant start dates by your last frost date. Here you can find a planting calendar for the area of Toronto. You can change the area on their website as well.

Leggy seedling problems usually come from 3 causes: lack of light, temperature and soil conditions. Lack of amounts of light is the main cause for seedlings to become leggy. A seedling needs a cycle of 16 hours of light a day and 8 hours of dark. Both light and dark are important.

To improve your leggy seedling,

  • Reduce the temperature, especially at night;
  • Increase the light intensity;
  • Reduce overcrowding and/or pinch out the growing tips. Seedlings will develop best if there is only one plant per pot.
  • When the seedlings get their second pair of leaves, prepare individual pots filled with a potting mix with plenty of compost. Move the seedlings carefully to the new pots and water well. Keep pots out of direct sun for a few days.
  • Plants in the tomato family, including peppers and eggplant, produce new roots from their lower stem if it is buried. When you transplant them outside or to a new pot,dig a hole that is two to three times the width of the original planting container and deep enough to bury 1/2 to 3/4 of the transplant stem to allow enough room for the plant to develop strong roots.
  • 7 to 10 days before transplanting, set the seedlings outdoors in dappled shade that is protected from winds for a few hours each day, gradually increasing their exposure to full sun and windy conditions. Keep the soil moist at all times during the hardening-off period. Dry air and spring breezes can result in rapid transpiration.

You might like to review our Gardening Guide — Growing from Seed.