When to Start Tomato Seeds Indoors in Minnesota Zone 4-5
Tomatoes are the most popular home garden vegetable, but this warm season plant needs a lot of time to grow and produce fruit. Because the plant needs so much time to maturity, experts strongly recommend that you start your tomato seeds indoors to get a head start on our short Minnesota growing season.
When to Start Tomato Seeds Indoors
Whether you’re growing sauce, slicing, or cherry tomatoes you want to start the seeds about six weeks before your last frost date. For most Minnesota gardeners this will be sometime in early April. For Washington County, this usually means you want to start seeds around April 3rd.
You should resist the urge to start your tomato seeds earlier, as per the University of Minnesota Extension:
“Plants started earlier are difficult to manage and do not necessarily lead to better or earlier harvests. “
One exception to this rule are tomatoes that will be grown in containers. If you can transplant the seedling into its final container at six weeks (and have an indoor space that can accommodate the container and provide enough light) then you might get an earlier harvest by starting your seeds a few weeks sooner. Note, however, that hardening off can be more difficult for more mature plants.
Tips on Starting Tomato Seeds Indoors
- Plant seeds about a quarter inch deep and keep them constantly moist until germination
- Tomato seeds germinate best at warm temperatures (75F – 85F). Use a germination heating mat if you have one. If you don’t, place your seed tray on a warm (but not hot) surface, such as the top of a refrigerator. Keep in mind your seeds don’t need any light until after they germinate. Move under lights as soon as you see one seedling emerge.
- Tomato seedlings grow best under a grow light as it is difficult to provide enough natural light to prevent tomato seedling from becoming leggy just with the April sunlight coming in most windows.
