Authored by:
Earth Science Team
For some gardeners, the last frost is but a distant memory. For others, it’s right around the corner. We put together a guide for what vegetables to plant this month, no matter where you are.
March is one of the most exciting months on the gardening calendar. It’s also one of the most confusing. Depending on where you live, March might mean snow still on the ground or tomato seedlings already in the garden. The secret to making March work for you comes down to one thing: knowing your USDA hardiness zone.
The USDA Plant Hardiness Zone Map divides the country into zones 1 through 13. Your zone tells you which plants can survive your winters and, combined with your last frost date, it gives you a clear starting point for spring planting.
One caveat before we dig in: Zones are guides, not guarantees. Microclimates, raised beds, and local weather patterns all matter. A south-facing raised bed can behave a full half-zone warmer than your yard’s baseline — which is worth knowing before you start counting backward from your last frost date.
Here’s what March looks like, zone by zone.
If you’re in Zones 3 or 4, your last frost probably won’t arrive until May. March is mostly an indoor month for you, but that doesn’t mean there’s nothing to do.
Start onions, leeks, and celery under grow lights now. These slow growers need the lead time. Zone 4 gardeners can also get tomatoes and peppers going in late March. Pro tip: Check your last frost date carefully, since starting too early leads to leggy, root-bound seedlings by May.
Outdoors, hold off on direct sowing. The ground is still frozen or barely thawed in most of these zones, but late March is a good time to assess your soil. Once it’s dry enough to work without compacting, that’s your cue to start amending. If your beds have been worked hard over the years or have never been properly restored, a soil amendment like Earth Science RevitaSoil — made with earthworm castings, natural nutrients, and beneficial microbes — can help rebuild structure and biological life before you put anything in the ground. Raised beds, which warm up faster than in-ground plots, may give you a slight head start.
March gets busy in Zones 5 and 6. Last frost in Zone 6 falls around April 15–30; Zone 5 gardeners are working toward a May 1–15 target. Both zones are juggling indoor seed starting and cautious first outdoor sowings simultaneously.
Indoors, start tomatoes and peppers now (6–8 weeks before last frost for tomatoes; 8–10 weeks for peppers and eggplant). Hold off on squash and cucumbers until late March. They grow quickly and hate transplanting, so starting them too early just creates problems. Annual flowers like marigolds, zinnias, and cosmos can get going this month too.
Outdoors, peas are the classic first crop. Zone 6 gardeners can get them in early March; Zone 5 by mid-month. Spinach, kale, arugula, and lettuce can be direct-sown in late March, especially under row covers or in cold frames. Onion sets go out in Zone 6 in early to mid-March, Zone 5 by late March. And if you’re in Zone 6, potatoes can go in around St. Patrick’s Day with frost protection.
This is where March really opens up. Last frost in Zone 7 is around April 1–15; Zone 8 may already be past it by March 1. Cool-season crops can go outside in earnest, and warm-season seed starting is underway.
Direct-sow beets, carrots, kale, lettuce, peas, spinach, and Swiss chard outdoors throughout March. Broccoli and cabbage transplants go out mid-month in Zone 7, earlier in Zone 8. March is also prime time for asparagus crowns — a perennial crop that, once established, can produce for 20 or more years. Potatoes follow the same St. Patrick’s Day rule here that holds in Zone 6.
Zone 8 gardeners who started tomatoes and peppers in January are now getting ready to transplant. Zone 7 gardeners starting those crops now should aim for early March, about six to eight weeks before last frost.
If your soil has been carrying cool-season crops through winter or is coming out of a long dormant stretch, this is also a good moment to restore it before the heavy growing season begins. Working an amendment like Earth Science RevitaSoil into your beds replenishes nutrients and reactivates the microbial activity that fuels spring growth, without needing to replace your soil entirely.
In Zones 9 and 10, the gardening calendar is almost inverted. Summer heat — not winter cold — is what shuts crops down. March is a race to get warm-season crops in before the heat arrives, while simultaneously wrapping up cool-season growing.
Soil temperatures are at or above 60°F in most of these zones by March, making it ideal for direct sowing beans, corn, squash, cucumbers, melons, okra, and Southern peas. For tomatoes and peppers, skip direct sowing at this stage and work from transplants. Starting from seed now risks the plants hitting peak production right as summer temperatures spike.
Zone 10 gardeners should get any remaining root vegetables and cool-season greens in the ground in early March before the window closes. If you’re starting to think heat-tolerant, look at Malabar spinach, New Zealand spinach, and Asian greens like bok choy and mizuna as warmer alternatives to traditional cool-season leafy crops.
It’s also worth noting: Gardeners in these zones often deal with soil that’s been through year-round production, which can mean depleted nutrients and worn-out structure. Rather than just adding more fertilizer, restoring that biological foundation is what ultimately makes the difference for back-to-back growing seasons.
The beauty of zone-based planning is that it removes the guesswork. Whether you’re nursing seedlings under grow lights in Minnesota or already direct-sowing beans in California, there’s a version of March gardening that works for your corner of the country. The key is knowing your zone, knowing your last frost date, and, before anything else goes in the ground, making sure the soil underneath is ready to do its job.
