When To Start Tomato Seeds

Start tomato seeds indoors or in a greenhouse before planting season. You can save money and choose a bigger variety of tomato varieties to grow. (More tips for growing your own tomato seedlings.)

If you start your own tomato seedlings, then when spring comes your plants will be ready to plant outdoors. Plus you'll grow a more successful crop than if you sow seeds directly in the garden.

But when should you start yours?

What's the best seed starting date?

When to start tomato seeds: how to choose a start date with Tomato Dirt #GrowingTomatoes #HomeGardening

By mid-winter, most gardeners are itching to get growing. Here's where you need patience.

Start too early and your plants will outgrow their pots quickly and become leggy, root-bound, and weak. They’ll spend their first weeks in the garden regaining strength, rather than producing new leaf growth and flowers.

Start your seeds late and you can have a delayed crop.

Timing your tomato seed starting is not a one-size-fits-all. Much depends on your climate.

Start dates differ from region to region ... even within a gardening zone.

How to know when to start tomato seeds

Try these 2 easy steps to calculate the best time to start your seeds where you live.

1. Determine the last frost date for your region. If you’re not sure, contact your local extension office. You can also view the freeze/frost information provided by the National Climatic Data Center.

2. Count back 4-6 weeks. Your last frost date is a guideline. Use it combined with current conditions. Count back from the last frost date for your region to determine when to start your tomatoes. Remember: tomatoes like to be warm, so if the extended forecast is cool and wet then err on the side of waiting a little longer.

Plant your tomato seedlings outdoors 1-2 weeks after the last frost date

Waiting longer to plant after the last frost date will reduce the chance of losing your tomato crop to freeze and will allow the ground to warm – which is the kind of environment in which tomatoes do best!

Sample calculation
The last frost date in upstate South Carolina: April 15
Ideal tomato seed starting date: March 1
When to plant tomato seedlings: April 25-May 7

From other Tomato Dirt-ers

Dear Tomato Dirt,
Why should I wait a couple of weeks after the last frost date to plant my seedlings in the garden? I want to get my tomato plants in the ground as soon as I can so I can have the first tomato on the block.
Sincerely, Itchy Garden Gloves

Dear Itchy,
Tomatoes like hot weather. They don’t like wet feet and they don’t like to be cold. Give the ground a chance to warm up and your tomatoes will reward you. Go with the calendar even if you're impatient.

If you absolutely must plant early, then use the “Black Plastic Trick.” Two to three weeks before setting tomatoes in the garden, cover your planting area with black garden plastic. Black absorbs heat from the sun and will warm your soil more quickly than if it is left to nature’s devices.

Happy gardening!
Sincerely, Tomato Dirt

More Tips for Starting Tomato Seeds

Grow tomatoes from seeds: what you need to know

Seed starting containers to use when you sow tomatoes

What seed starting mix to use for growing tomato seeds ...

Seed starting mix for tomatoes: what ingredients are important ...

Review: Pro-Mix Seed Starting Formula for growing tomato seeds ...

How to germinate seeds to get best results when growing tomatoes

How to label and grow tomatoes from seed ...

How to plant tomato seeds ...

Tomato growing tips for seeds ...

Learn what tomato seedlings need after they germinate

Re-potting tomato seedlings to a bigger container ...

Strengthen a growing tomato plant to prepare it for the home garden

Return from Tomato Seeds: When Should You Start Them? to Tomato Dirt home