When to plant tomato seeds indoors in Ontario

Tomatoes are one of the most popular vegetables to grow in Ontario gardens. Growing your own tomato plants from seed is a great way to save money and ensure that your plants are free from disease or pests. However, it's essential to know when to plant your tomato seeds indoors to ensure that they have enough time to mature before being transplanted outside.

What is indoor seed starting?

Indoor seed starting is the process of sowing seeds in containers indoors, typically eight to 12 weeks before the last frost date in your area. This allows the seeds to germinate and grow into healthy plants before being transplanted outside.

When to start tomato seeds indoors in Ontario

In Ontario, it's generally recommended to start tomato seeds indoors around six to eight weeks before the last expected frost date in your area. The last frost date varies across Ontario, but generally, the southern part of the province experiences the last frost around mid-May, while the northern part of the province has its last frost around early June.

If you're unsure of your last frost date, there are several online resources that can help you determine it. Once you have your last frost date, count back six to eight weeks, and that will give you your indoor seed starting date.

How to start tomato seeds indoors

When starting tomato seeds indoors, it's essential to use a good-quality seed-starting mix that's light and well-draining. Fill containers or seed trays with the mix and plant the seeds according to the package instructions, typically around 1/4 inch deep. Keep the soil moist, but not saturated, and cover the containers with plastic wrap to create a greenhouse effect.

Put the containers in a warm spot in your home, ideally around 70°F. Once the seeds start to germinate, remove the plastic wrap and move the seedlings to a sunny location, like a south-facing windowsill, or under grow lights.

Transplanting your seedlings outside

After your seedlings have grown to around six to eight inches tall, they're ready to be transplanted outside. You'll need to "harden off" your seedlings first, which involves gradually exposing them to outdoor conditions, so they're acclimatized and less likely to suffer transplant shock.

To transplant your seedlings outside, choose a site with full sun and well-draining soil. Dig a hole slightly deeper than the root ball of your seedling, and gently place it in the hole. Fill the hole with soil, press it down gently, and water thoroughly.

In conclusion

Starting tomato seeds indoors is a fun and cost-effective way to grow your own tomato plants. By following the guidelines mentioned above, you can ensure that your tomato seeds are planted at the right time and that they thrive both indoors and outdoors. Happy gardening!