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Vegetable Crop Calendars (A–C)Tomato Planting Calendar: Start, Transplant, Harvest
Tomatoes ride on three dates: when you start seed, when you set plants out, and when frost ends the season. Get the middle one right and the other two follow.
Key points
- Choose your transplant date first and count back to find the seed date.
- Plant after frost danger passes and nights are reliably mild.
- Check days to maturity against your first fall frost.
- Preserve tomatoes only with tested procedures.
When should you start tomato seed indoors?
University of Minnesota Extension notes that peppers are started earlier than tomatoes, about eight weeks before transplanting, which tells you tomatoes need somewhat less lead time. Your seed packet or local extension office gives the exact number of weeks for tomatoes in your area.
To get the date, choose your planned transplant date first, then count backward. For example, if you expect to plant out in mid May, your sowing date falls several weeks earlier, and you would check the packet for the figure.
Keep seedlings under bright light close to the plants. Leggy seedlings from a dim window transplant poorly, so give them strong light from the start.
When can tomatoes go in the garden?
Tomatoes are frost tender and slow to grow in cold soil. Plant after your average last spring frost, once nights are reliably mild and the soil has warmed. The National Weather Service or your county extension office can give your frost date, but the forecast matters more than the average.
Harden plants off over a week or more. Plant in late afternoon or on a cloudy day, and keep covers ready for a cold night.
Many gardeners place plants out in stages, with a few early plants protected by covers and the main planting later after the weather settles.
How deep should you plant tomato transplants?
Tomatoes can root along buried stems, so many gardeners plant them deeper than they grew in the pot, removing lower leaves. This builds a stronger root system.
Some people lay a long leggy plant sideways in a shallow trench with the top bent upward. Either way, water in well and stake or cage at planting so you do not damage roots later.
Here is a worked example. Suppose you plan to transplant on May 20 and your packet suggests about six weeks of indoor growth. Sowing would fall around the second week of April. This is an example only, so use your packet and your own frost date.
How long until you harvest tomatoes?
Days to maturity on the packet usually count from transplanting for tomatoes, but check each supplier's wording. Early varieties may ripen in less time than large heirloom types, which can need many more weeks of warm weather.
Compare the days with your average first fall frost. If frost comes first, choose earlier varieties or plant sooner. Fruit stops ripening well in cool nights, and a frost can end the plant.
Determinate types set fruit over a shorter window, while indeterminate types keep growing and fruiting until frost. Check your variety to know which kind you have and plan staking accordingly.
What mistakes slow tomatoes down?
Planting too early is the most common one, followed by skipping hardening off and crowding. Leaf diseases spread faster in humid, crowded plantings, so stake plants and leave space.
Rotate tomatoes away from beds where tomatoes, peppers, potatoes or eggplant grew recently. Water the soil, not the leaves, and mulch to keep soil from splashing onto foliage.
Consistent watering prevents many problems, so a simple soil moisture check with a finger a few inches down is better than a fixed schedule.
What about pests and diseases?
Hornworms, blight, blossom end rot and cracking appear in many regions. Some problems are cultural, such as uneven watering, rather than infectious.
Ask your county extension office for identification and current options. Follow labels exactly, observe pre-harvest intervals and mind pollinators. For canning or preserving tomatoes, use only tested procedures from the National Center for Home Food Preservation, since tomato acidity needs careful handling.
A common mistake is to buy very large transplants early and keep them waiting. Overgrown, rootbound plants set back faster than small, healthy ones, so match your sowing date to your planting date.
What does a tomato calendar look like step by step?
Here is the sequence, counted back from transplant day. Adjust the weeks using your seed packet or extension guidance.
Follow it in order:
- Pick the transplant date from your last frost and the forecast.
- Count back the weeks your packet suggests and sow indoors.
- Bring seedlings under bright light and keep them evenly moist.
- Harden off over a week or more before transplant day.
- Transplant deep, water in, and stake or cage at once.
- Compare days to maturity with your first fall frost and plan harvest.
Sources and further reading
Last reviewed: November 2026. Educational information, ranges only. Confirm timing with your county extension office.