Plant tomatoes in Maryland after the last spring frost, which falls between May 1 and May 15 depending on your location in the state

Maryland's frost date is the single date that matters for tomatoes. Tomato plants die when exposed to frost, so planting before that date wastes the seedling. The last spring frost in Maryland ranges from early May in the southern counties (around Baltimore and the Eastern Shore) to mid-May in the western mountains. If you plant on May 1 in Anne Arundel County and May 15 in Garrett County, you are working with the frost dates your area actually experiences.

You can start seeds indoors 6 to 8 weeks before your frost date—that means late February or early March for most of Maryland—but the seedlings stay inside until after the frost passes. Hardening off (moving seedlings outside for a few hours each day to acclimate them) takes about a week and should happen in late April, just before transplanting into the garden.

Key Takeaways

  • Maryland's last spring frost falls between May 1 and May 15; plant tomatoes after that date, not before.
  • Start seeds indoors in late February or early March if you want larger plants ready to transplant, but keep them inside until late April.
  • Soil temperature should reach at least 60°F before planting, though tomatoes grow faster when soil is 70°F or warmer.
  • A second planting in late June or early July can produce a fall harvest before the first frost, which arrives in October in most of Maryland.
  • Check your specific county's frost dates through the University of Maryland Extension, as timing varies across the state.

Finding Your Exact Frost Date by County

Maryland spans a wide range of elevations and climates. The Eastern Shore and southern counties warm up earlier than the mountains, so a statewide date is not precise enough. The University of Maryland Extension publishes frost dates for each county, and that is the number to use for your garden.

You can find your county's frost date on the University of Maryland Extension website by searching "[your county] frost date." The dates are based on 30 years of weather records and represent the average date of the last frost in spring. Some years frost comes earlier, some later, but planting on or after that date gives you the best odds.

Soil Temperature Matters as Much as Air Temperature

A warm air temperature does not mean the soil is warm enough. Tomatoes planted in cold soil sit dormant and often rot before they grow. Soil should reach at least 60°F before you transplant, though 70°F is better—tomatoes germinate and grow much faster in warmer soil.

You can check soil temperature with a soil thermometer, which costs a few dollars at any garden center. Stick it 4 inches into the ground in the morning. If you do not have a thermometer, wait until the soil feels warm to the touch and grass and weeds are growing actively—that usually means the soil has warmed enough.

Hardening Off Seedlings Before Transplanting

Seedlings started indoors are tender and will wilt or die if moved directly into the garden. Hardening off toughens them up over 7 to 10 days. Start by setting seedlings outside in a sheltered spot for 2 to 3 hours on a mild day, then bring them back inside. Each day, leave them out a bit longer and expose them to more direct sun and wind.

By the end of the hardening-off period, seedlings should spend a full day outside in dappled sun or morning sun. After that, they can go into the garden. If a late frost is forecast while seedlings are hardening off, move them back inside or cover them with a frost cloth overnight.

A Second Planting for Fall Tomatoes

Maryland's growing season is long enough for a second tomato crop. Plant seeds or seedlings in late June or early July, and they will mature before the first fall frost, which typically arrives in mid-October in most of Maryland (earlier in the mountains, later on the Eastern Shore).

Fall tomatoes often taste better because they ripen in cooler weather, but they have less time to grow. Choose faster-maturing varieties—look for 60- to 75-day varieties on the seed packet. Determinate tomatoes (bush types that ripen all at once) work better for fall planting than indeterminate types (vining varieties that produce all season).

Choosing Between Seeds and Seedlings

Starting from seed indoors gives you more variety choices and costs less per plant. You need grow lights, a heat mat, and space indoors for 6 to 8 weeks. If you do not have those, buying seedlings from a garden center or nursery is faster and simpler—you skip straight to hardening off and transplanting.

Seedlings are usually available at Maryland garden centers from mid-April through May. Buy plants that are stocky and green, not tall and spindly or already flowering. Flowering seedlings are stressed and often produce less fruit than plants that flower after transplanting.

Protecting Young Plants from Late Frost

Even after the average frost date passes, a cold snap can arrive. If frost is forecast within a week of planting, cover plants with a frost cloth, old sheets, or row cover at night and remove it during the day. Do not use plastic—it conducts cold and can damage plants. Cloth traps warmth from the soil.

If plants are already in the ground and frost hits, water them thoroughly the night before and the morning after. Moist soil holds heat better than dry soil. Frost damage shows as blackened or wilted leaves; if the stem is still green and firm, the plant usually recovers.

Frequently Asked Questions

Can I plant tomatoes before May 1 if I use a frost cloth?

Frost cloth helps, but it is not reliable for repeated frosts. If you plant in late April and frost comes several nights in a row, you will be covering and uncovering constantly, and the plant may still be damaged. Waiting until after your frost date is simpler and more reliable.

What if I buy seedlings at the store and they are already flowering?

Flowering seedlings are stressed and often drop flowers after transplanting. If that is all available, buy them, but pinch off the flowers before planting. The plant will redirect energy into roots and new growth instead of trying to set fruit in poor conditions.

Do I need to start seeds indoors, or can I direct-seed tomatoes in the garden?

Tomatoes need a long growing season, so direct seeding in Maryland usually does not work—seeds planted in May will not mature before frost. Starting indoors or buying seedlings is the standard approach. Direct seeding works only if you choose very fast varieties and live in the warmest part of the state.

What is the difference between determinate and indeterminate tomatoes for Maryland?

Determinate (bush) tomatoes ripen all their fruit in a short window, usually 60 to 75 days. Indeterminate (vining) tomatoes produce fruit all season until frost. For spring planting, either works. For fall planting, determinate is better because it finishes before the first frost.

Can I plant tomatoes in containers instead of the ground?

Yes. Containers warm up faster than garden soil in spring, so you can plant a week or two earlier. Use a pot at least 5 gallons for a full-size tomato plant, fill it with potting soil (not garden soil), and water more often because containers dry out faster than the ground.