Plan your spring garden from one date. Enter your average last frost date and get when to start each crop indoors, when to harden off and transplant, and the window for sowing directly in the garden, with a timeline for 30 vegetables, herbs and flowers.
Last updated:
Look it up for your ZIP code or town (local extension service or almanac).
Pushes tender transplants and sowing later; indoor starts move with it.
Enter your values to see the result.
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How to use the Seed Starting Date Calculator
Find your last frost date from your local extension service, a frost-date lookup or an almanac, and enter it.
Pick a crop to see its indoor start, hardening-off, transplant and direct sow dates.
Add a safety margin if late frosts are common where you live.
Scan the timeline and table to plan every crop in your garden.
Download the CSV or copy the result to keep with your seed packets.
How seed starting dates are calculated
Every date is counted from your average last spring frost: start date = last frost − weeks before, and transplant or sowing date = last frost ± weeks.
Example with a last frost of April 15: tomatoes start indoors 8-6 weeks before (Feb 18 - Mar 4), harden off in late April and go outside 1-2 weeks after the frost (Apr 22 - Apr 29).
Peas are sown directly 6-4 weeks before the frost (Mar 4 - Mar 18).
Cool-season crops (peas, spinach, lettuce, cabbage family) tolerate light frost and go out before the frost date. Warm-season crops (tomatoes, peppers, squash, beans, corn, basil) are killed by frost and go out after it, once the soil is warm.
Seed starting chart (weeks relative to last frost)
Crop
Start indoors
Transplant
Direct sow
Tomato
6-8 wk before
1-2 wk after
—
Pepper
8-10 wk before
2-3 wk after
—
Eggplant
8-10 wk before
2-3 wk after
—
Broccoli
6-8 wk before
2 wk before to frost date
2-4 wk before
Cabbage
6-8 wk before
2-4 wk before
2-4 wk before
Cauliflower
6-8 wk before
2 wk before to frost date
—
Kale
4-6 wk before
2-4 wk before
3-5 wk before
Lettuce
4-6 wk before
1-3 wk before
4 wk before to 2 wk after
Swiss chard
4-6 wk before
2 wk before to frost date
2 wk before to 1 wk after
Onion (from seed)
10-12 wk before
2-4 wk before
—
Leek
10-12 wk before
2 wk before to frost date
—
Celery
10-12 wk before
1-2 wk after
—
Parsley
8-10 wk before
2 wk before to frost date
1-3 wk before
Basil
6-8 wk before
1-2 wk after
1-2 wk after
Cucumber
3-4 wk before
1-2 wk after
1-3 wk after
Zucchini / summer squash
3-4 wk before
1-2 wk after
1-3 wk after
Winter squash / pumpkin
3-4 wk before
2-3 wk after
1-3 wk after
Melon / watermelon
3-4 wk before
2-3 wk after
2-4 wk after
Spinach
—
—
3-6 wk before
Peas
—
—
4-6 wk before
Radish
—
—
1-5 wk before
Carrot
—
—
3 wk before to frost date
Beet
—
—
1-4 wk before
Cilantro
—
—
1 wk before to 2 wk after
Beans (bush & pole)
—
—
1-3 wk after
Sweet corn
—
—
1-3 wk after
Sunflower
—
—
frost date to 2 wk after
Marigold
6-8 wk before
frost date to 1 wk after
frost date to 2 wk after
Zinnia
4-6 wk before
1-2 wk after
frost date to 2 wk after
Cosmos
4-6 wk before
frost date to 2 wk after
frost date to 2 wk after
Timings follow common university extension and seed-company guidelines and vary by variety and climate. Check your seed packet and soil temperature before planting.
Frequently asked questions
When should I start seeds indoors?
Count back from your average last frost date. Tomatoes are started 6-8 weeks before it, peppers and eggplant 8-10 weeks, onions and leeks 10-12 weeks, and cucumbers, squash and melons only 3-4 weeks because they grow fast and dislike root disturbance.
What is the last frost date?
It is the average date of the last 32°F (0°C) freeze in spring for your location, usually based on 30 years of weather records. There is still roughly a 50% chance of a later frost, which is why many gardeners add a week or two of margin for tender plants.
When can I transplant tomatoes outside?
About 1-2 weeks after the last frost date, when nights stay above about 50°F (10°C) and the soil has warmed. Harden the seedlings off for 7-10 days first by setting them outside for gradually longer periods.
Which crops should be sown directly in the garden?
Root crops (carrots, radishes, beets), peas, beans, corn, spinach and sunflowers grow best when sown directly, because they either dislike transplanting or grow quickly from seed. Peas and spinach go in several weeks before the last frost; beans and corn after it.
What does hardening off mean?
It is getting indoor seedlings used to sun, wind and cooler nights before transplanting. Start with an hour or two in the shade and increase the time and sun exposure each day for 7-10 days.
Are these dates exact?
They are typical ranges from common extension-service and seed-company guidance. Always check the seed packet, which may give different timing for a specific variety, and adjust for your local weather and soil temperature.
Are all the tools on FreeToolCabin tested for quality and accuracy?
Yes! Every tool on our site undergoes automated Q/A testing in real browser environments to ensure high precision, correct output, and zero errors. If you happen to spot a bug or have a suggestion, please contact us at [email protected] and our team will review it right away.