Best Seeds to Plant in March - Get These Started Now

March is a busy seed starting time for us at Sow Right Seeds. We’re filling up our indoor grow station and planting seeds in our hoophouse.

March seed starting depends on temperatures in your location and the expected last frost date. You can enter your zip code into our planting planner to see your expected last frost date and which seeds to start indoors or direct sow.

The key to success in March is understanding your last frost date and soil temperature. This month is ideal for planting cool-season crops directly outdoors while starting warm-season favorites indoors so they’re ready to transplant after frost danger passes.

For many gardeners and us, March is when the growing season truly begins.

Planting in March looks different depending on where you live. Gardeners in zones 7–10 may already be sowing outdoors, while zones 3–6 are still working around lingering frost.

Use your local last frost date as your anchor. In general:

• Direct sow now: Cool-season vegetables that tolerate frost.

• Start indoors now: Warm-season crops that need a long growing season.

When in doubt, check soil temperature. Many early crops germinate once the soil reaches 40–50°F.

On the back of the seed packet, you'll see a germination temperature. So, although some crops will grow and thrive in cool weather, they may need warm soil to germinate. This is why we often start broccoli and cabbage seeds indoors.

Peas
Peas love cool weather and should be planted as soon as the soil can be worked. Provide trellising early for strong support. Soil should be about 50ºF.

Spinach
Spinach thrives in chilly conditions and can even handle a light freeze. Sow successively every 10–14 days for continuous harvests. You can even winter sow spinach seeds.

Lettuce
Leaf lettuce varieties are perfect for early planting. They germinate quickly and mature fast, giving you fresh salads by late spring.

Radishes
One of the fastest crops you can grow. Radishes are ideal for filling empty spaces and can be ready in as little as 25–30 days.

Carrots
Carrots prefer cool soil for germination. Carrot seeds can sprout in soil as cool as 45ºF, but 50ºF is ideal. Keep the seedbed consistently moist until seedlings emerge. 

Mustard Greens & Swiss Chard
Both tolerate cool temperatures and provide flavorful early harvests. These seeds will germinate in soil as cool as 45ºF. 

March is the ideal time to start long-season crops indoors so they’re ready for transplanting after your last frost. The seeds to start indoors are your warm summer loving plants. By starting them indoors you’ll have a longer growing season.

Tomatoes
Start seeds 6–8 weeks before your last frost date. Provide strong light immediately after germination to prevent leggy seedlings.

Peppers & Eggplant
These warm-season crops benefit from early indoor sowing. They prefer warm soil (70–80°F) for germination.

Basil & Other Tender Herbs
Start basil indoors to get a head start before warm weather arrives.

Cucumbers & Squash (Late March in Cooler Zones)
In cooler regions, you may wait until late March or early April. These grow quickly and don’t need as much indoor lead time as tomatoes.

March isn’t just for vegetables.

Cool-Season Annual Flowers
Snapdragons, calendula, and sweet peas can be direct sown in mild climates or started indoors in cooler zones.

Hardy Herbs
Cilantro, parsley, chives, and dill can be direct sown once soil is workable.

Adding flowers and herbs early helps attract beneficial insects and creates a balanced spring garden.

If some beds won’t be planted immediately, March is a great time to improve your soil. Quick-growing cover crops such as clover or field peas can suppress weeds and add organic matter.

Even if you’re planting vegetables soon, top-dressing beds with compost now boosts soil fertility before heavy spring growth begins.

Prepare Beds Early
Remove winter debris and loosen compacted soil once it’s dry enough to work.

Warm the Soil
In cooler climates, covering beds with black plastic or row cover can help soil warm faster.

Harden Off Seedlings
If you’ve started plants indoors, gradually acclimate them to outdoor conditions before transplanting.

Succession Planting
Stagger plantings of lettuce, radishes, and spinach every couple of weeks to extend harvests into late spring.

Protect from Frost
Keep row covers or frost blankets on hand. March weather can change quickly.

Review our March Garden Checklist for garden tasks to do this month.

Direct Sow Now:
Peas, spinach, lettuce, kale, radishes, carrots, mustard greens, chard, cilantro

Start Indoors Now:
Tomatoes, peppers, eggplant, basil

Late March (Zone Dependent):
Cucumbers, squash, melons

March sets the tone for the entire gardening season. By planting cool-season crops outdoors and starting warm-season vegetables indoors, you create a steady rhythm of harvests that will carry you through spring and into summer.

Check your frost dates, prepare your soil, and start sowing. A productive garden year begins in March.