When to Start Vegetable Seeds Indoors for Spring Planting

Seedlilngs growing in containers

When starting seeds indoors for spring planting, timing is very important. The plants need to be large enough to move outdoors at the normal planting time, without being spindly and overgrown.

To figure out when to start your seeds, you need to know three things:

  • Frost Date: Your average last spring frost date is the key to planting in your area.
  • Growing Time: You need to know the average number of weeks between planting seeds and transplanting seedlings. The growing time varies depending on what you’re planting and should be on the seed packet label. The average growing time is usually between 4 and 12 weeks.
  • Planting Time: Warm-season vegetables can’t go outside until after the last frost while cool-season veggies can go outside up a month before the last frost.

Instructions on seed packet on when to plant seeds indoors

Once you’re armed with the correct information, it’s a matter of some simple math to figure out when to start your seeds. For example, tomato seeds require 6-8 weeks growing time until planting, and they can’t be transplanted until after the last spring frost.

Since the average last frost date is around April 8 in my area, I should start these seeds between February 11 and 25 to give them 6-8 weeks to grow for planting after April 8. To be safe, I err on the late side, to reduce the risk of a surprise late season frost or freeze.

Gardening Tip

For a longer harvest, schedule several plantings of seeds, each a week or two apart. Not only will staggered plantings extend your harvest season, but successive groups of seedlings act as insurance against a deadly surprise cold snap.

Working out your first seed schedule can be a little complicated, but with practice you’ll find that most vegetables and flowers fall into groups that can be planted together. Save yourself future work by transferring your schedule to a seed calendar that you can refer to year after year.

Seed planting calendar

Spring Transplant Schedule for Popular Vegetables

Be sure to check the label of each seed packet, since different varieties of a particular vegetable may have different levels of cold tolerance. Here’s a general guide to help you plan your spring planting times:

Vegetable Indoor Growing Time Outdoor Planting Time
Broccoli 5-7 weeks 4-6 weeks before last frost
Cabbage 5-7 weeks 4-6 weeks before last frost
Corn 4-5 weeks After last frost
Cucumber 3-4 weeks After last frost
Eggplant 6-8 weeks After last frost
Lettuce & Spinach 4-6 weeks 4 weeks before last frost
Okra 6-8 weeks After last frost
Pepper 6-8 weeks After last frost
Pumpkin 3-4 weeks After last frost
Summer Squash 3-4 weeks After last frost
Tomato 6-8 weeks After last frost
Watermelon 3-4 weeks After last frost

Further Information


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When to Start Vegetable Seeds Indoors for Spring Planting