March is when planning meets planting. Soil is warming, frost risk is declining, and the pace accelerates quickly. The key is to move fast without rushing — soil temperature matters more than a warm week.

March tasks

Check soil temperature daily

Begin measuring soil temperature at 2 inches deep each day, at the same time. Record the readings. This is the single most important decision-making tool for March planting:

  • Below 50°F: Warm-season crops will rot in the ground. Stick to cool-season crops.
  • 50–60°F: Cool-season crops germinate slowly but reliably.
  • 60–70°F: Good for cool-season crops; some warm-season crops can go in with caution.
  • 70°F+: Warm-season crops germinate well; succession-plant peas and beans.

Dark mulch, bare ground, and south-facing beds warm faster than ground under light-colored mulch. Use these microclimates strategically. A bed against a south-facing wall or fence can run 5–10°F warmer than an open bed just a few feet away, because the structure absorbs daytime sun and re-radiates heat overnight — reserve those warm spots for the earliest warm-season plantings and use cooler, shadier beds for crops that bolt in heat later on.

Clear plastic warms soil fastest; black plastic is close behind and blocks weeds too. Laying either over a bed for 1–2 weeks before planting can raise soil temperature several degrees compared to bare, uncovered soil, buying you a week or more of head start without any protection needed for the plants themselves — you're only warming empty ground, not shielding foliage from frost.

Watch the last frost date

Your last spring frost date is a probability, not a guarantee. Know both your 50% and 10% dates:

  • 50% date: A coin flip. Cheap, re-sowable crops can go out.
  • 10% date: Very likely frost-free. Irreplaceable plants (grafted trees, heirloom tomatoes you waited all winter for) should wait.

In March, frost risk is still real. Plan protections if you transplant early.

Continue hardening off transplants

If February seedlings aren't fully hardened yet, finish the process. Seedlings hardened through the second week of February can go in the ground mid-to-late March (depending on frost risk). Seedlings started in early March are still a few weeks away.

Begin main-season succession planting

This month you start the pattern that runs through July: plant the same crop every 1–2 weeks so harvests overlap rather than arrive all at once:

  • Peas and beans: Plant weekly through June
  • Lettuce and spinach: Plant every 10–14 days through June
  • Carrots and beets: Plant every 7–14 days through June
  • Radishes: Plant every 7–10 days through July

The easiest way is to designate a planting day each week and sow whatever is ready that day, rather than obsessing over each crop individually.

Remove winter mulch from early beds

If you applied heavy mulch in fall to protect perennials, rake it back now to let soil warm and prevent rot. Leave a thin layer under remaining snow or keep it nearby to pull back over plants if frost threatens.

Work soil only when ready

Before digging or turning any bed, grab a handful of moist soil and squeeze it:

  • If it forms a hard ball that won't break apart, soil is too wet; wait
  • If it crumbles, soil is ready to work

Working wet soil destroys structure and creates clods that take years to fix.

When to transplant warm-season crops

Warm-season crops and timing

These crops are frost-tender and must not go out until frost risk has passed and soil is warm:

  • Tomatoes, peppers, eggplant: Wait for your 10% frost date or later. Soil should be at least 60°F, ideally 65°F+. Usually mid-April in zone 7, earlier in zone 8, later in zone 6.
  • Basil and warm-season herbs: Wait for your 10% frost date and 65°F+ soil. Basil is particularly frost-sensitive.
  • Tender perennials (mandevilla, etc.): Same as basil — very frost-sensitive.

Hardening off and transplanting procedure

  1. Fully harden off seedlings (10–12 hours outdoors for 2–3 days before planting)
  2. Water seedlings thoroughly the morning of transplanting
  3. Dig holes slightly larger than root ball
  4. Plant at the same depth as in the pot (except tomatoes, which can go deeper to bury stem roots)
  5. Press soil gently around roots
  6. Water immediately and thoroughly
  7. Provide shade cloth or afternoon shade for 3–5 days if conditions are very sunny
  8. Monitor moisture; transplants often wilt the first day or two but recover with consistent watering

Season extension for early transplanting

If you want to transplant warm-season crops before frost risk has fully passed:

  • Plant early, use row covers or low tunnels for frost protection
  • Or wait until frost risk is gone — the safest approach for home gardeners
  • Or use protections: wall-of-water cloches, cardboard boxes, or frost cloth

What each protection actually buys you. A wall-of-water cloche (a ring of water-filled plastic tubes around a single plant) can hold the interior several degrees above freezing even on a cold night, because the water's thermal mass releases heat slowly overnight — it's the most reliable single-plant protection for an early tomato, but it's labor-intensive to set up for more than a handful of plants. A cardboard box or overturned bucket placed over a plant at dusk and removed the next morning blocks radiational frost (the ice-crystal-forming kind that happens on clear, calm nights) reasonably well but does nothing against an advective freeze, where cold air moves in on wind — check the forecast for wind, not just temperature, before trusting a box alone. Frost cloth draped loosely over a hoop, as covered in the Seasonal Garden Planner, gives a few degrees across a wider area and is the better choice once you're protecting more than a few plants.

The real risk of transplanting early isn't a single frost night — it's a cold snap the week after. Even if the specific night of transplanting is frost-free, a run of cold nights in the following week can stall tomato and pepper growth for weeks even without killing the plant outright, through chilling injury that doesn't show symptoms until later. Watch the 7–10 day forecast, not just the transplant night, before deciding to go early.

What to direct-seed in March

Direct-seeded cool-season crops

These go in early March when soil is 40–50°F:

  • Peas: Sow every 7–10 days through mid-April
  • Fava beans: Sow in early March
  • Lettuce and spinach: Sow every 10–14 days through April
  • Arugula, mustard, other greens: Sow every 10–14 days
  • Carrots and beets: Sow every 7–14 days through April
  • Radishes: Sow every 7–10 days through June
  • Turnips: Early March

Direct-seeded warm-season crops

Only after soil reaches 60–70°F (usually late March in zone 7 or 8, later elsewhere):

  • Beans: Plant every 7–10 days through June when soil is warm
  • Corn: Plant when soil reaches 65°F+, every 10–14 days through mid-June
  • Squash, cucumbers, melons: Plant when soil is 70°F+ and frost risk has passed
  • Basil: Plant seeds directly outdoors (or transplants) after all frost risk

Planting depth and spacing

  • Peas: 1–1.5 inches deep, 2–3 inches apart
  • Beans: 0.75–1 inch deep, 3–4 inches apart
  • Carrots: 0.25–0.5 inch deep, thin to 2–3 inches apart
  • Lettuce: 0.25 inch deep, thin to 6–12 inches apart
  • Corn: 1 inch deep, 4–6 inches apart

Pea inoculant and support

Peas (and beans, later in spring) are legumes that partner with soil bacteria called rhizobia to fix atmospheric nitrogen into a form the plant can use. If you haven't grown peas in that bed before, or haven't in several years, a powdered rhizobial inoculant (sold alongside seed at most garden centers) coated onto the seed before planting measurably improves nodulation and nitrogen fixation — a few dollars of inoculant is cheap insurance. Install pea trellising at planting time rather than after the vines are up and tangled; even bush pea varieties benefit from light support once pods start weighing down the stems.

Bare-root and perennial planting

March, while plants are still dormant or just breaking dormancy, is prime planting season for bare-root stock and for dividing overcrowded perennials.

Bare-root fruit trees, berries, and roses are sold dormant with roots exposed (packed in moist material) rather than in a pot, and they're both cheaper and often better-established than container stock by the end of their first season, because the root system isn't circling a pot's confines. Plant as soon as they arrive if the ground is workable; if you must delay, keep roots moist and cool, and "heel in" (temporarily bury the roots in loose soil or mulch) if planting is delayed more than a few days. Soak bare roots in water for a few hours before planting, spread roots out over a mound of soil in the planting hole rather than jamming them in a clump, and plant at the same depth the roots show they grew at previously (look for a color change on the stem or trunk marking the old soil line).

Asparagus and rhubarb crowns go in as dormant crowns in March in most climates — asparagus in a trench 6–8 inches deep with crowns spread out and gradually backfilled as shoots grow, rhubarb with the crown's growing point just at or slightly below soil level. Both are long-lived perennials (asparagus beds can produce for 15–20 years), so bed preparation and placement deserve real thought before planting rather than after.

Bare-root strawberries should be planted with the crown itself right at soil level — buried too deep, the crown rots; planted too high, it dries out. Both mistakes are common and both are easy to avoid by planting to the visible line where roots meet crown.

Dividing overcrowded perennials. Many herbaceous perennials (hostas, daylilies, many ornamental grasses, chives, and other clumping herbs) benefit from division every 3–5 years as the center of the clump becomes congested and flowering declines. Dig the entire clump, and split it with a sharp spade or by hand into sections that each retain healthy roots and at least a few growing points, then replant divisions promptly so roots don't dry out. Early spring, just as new growth emerges, is one of the two best windows for this (the other being early fall) because the plant has the whole growing season ahead to re-establish.

Succession planting strategy

Succession planting prevents a glut followed by nothing. The goal is overlapping harvests.

The principle

Plant the same crop every 1–2 weeks, using the same amount of seed each time. After a few plantings, you'll have seedlings germinating, small plants growing, and mature plants to harvest in the same bed — staggered by about 2 weeks.

Which crops to succession-plant

  • Must-have: Lettuce, peas, beans, corn, radishes, carrots, beets
  • Optional: Spinach, arugula, chard, basil, dill, cilantro, kale, other greens

Which to skip

  • Tomatoes, peppers, eggplant: One succession (one transplanting) per season is enough
  • Squash, melons, cucumbers: Usually one or two plantings per season

A practical timeline for zone 7

  • March 1: First planting of peas, lettuce, carrots, radishes
  • March 8: Second planting of the same
  • March 15: Third planting; also start beans (when soil reaches 65°F)
  • March 22: Fourth planting of cool-season crops
  • March 29: Fifth planting if season-extension beds are available; otherwise shift focus to warm-season
  • April onward: Continue weekly plantings through June for cool-season, add warm-season successions

Adjust these dates for your hardiness zone and local frost pattern.

Early-season pest watch

Pest pressure in March is lower than summer, but a handful of early pests specifically target the tender seedlings and transplants this month brings, and catching them early is far easier than recovering from a wiped-out planting.

  • Cutworms sever young seedling stems at or just below the soil line overnight, often taking out an entire row of freshly transplanted brassicas or tomatoes in one night. A simple collar around each transplant's stem — a toilet paper tube, a cut section of cup, pushed an inch into the soil — physically blocks the worm from reaching the stem and is nearly 100% effective for the cost of saved cardboard.
  • Slugs and snails are especially damaging to young seedlings in cool, damp March weather, capable of demolishing a newly emerged lettuce or bean seedling in a single night. Handpicking at dusk, shallow dishes of beer set at soil level, or iron phosphate bait (safer around pets and wildlife than older metaldehyde baits) all help; damp mulch, while good for moisture, also shelters slugs, so watch mulched beds especially closely early on.
  • Seed corn maggot attacks germinating seeds of beans, corn, and peas directly in the soil, especially in cold, wet soil where germination is already slow — another reason not to rush warm-season seed into soil that hasn't reached temperature, since slow germination gives the maggot more time to find the seed.
  • Flea beetles emerge as soon as weather warms and go straight for brassica and eggplant seedlings, riddling leaves with small round holes. Row cover installed at transplant time, before adults find the bed, prevents the damage far more reliably than treating it after the fact.

Sources and further reading