When To Plant Corn In Massachusetts

If you’re planning your garden in the Bay State, knowing when to plant corn in Massachusetts is the first step to a successful harvest. Getting the timing right is crucial for this warm-season crop, and it all depends on the spring soil temperature.

Corn is a crop that thrives on warmth and cannot tolerate frost. Planting too early in cold, wet soil will lead to poor germination and rotted seeds. Planting to late can mean your corn doesn’t mature before fall’s first frost. This guide will walk you through the optimal spring planting schedule, tailored for Massachusetts’s unique climate zones.

The safest and most recommended time to plant corn in Massachusetts is from mid-May to early June. However, this is a general range. A much more accurate method is to watch the soil, not just the calendar.

You should plant corn when the soil temperature at a 2-inch depth consistently reaches at least 50°F (10°C). For optimal and rapid germination, aim for 55–60°F (13–16°C). You can use a simple soil thermometer to check this each morning for several days in a row.

Understanding Your Massachusetts Growing Zone

Massachusetts spans USDA Plant Hardiness Zones 5b through 7a. This variation means your last spring frost date can differ by two to three weeks across the state.

Zone 5b (Western Berkshire County, higher elevations): Average last frost around May 15th. Target planting from late May to early June.
Zone 6a & 6b (Most of central MA, including Worcester, and parts of the coast): Average last frost between April 30th and May 10th. Target planting from mid-May onward.
Zone 7a (Cape Cod, Islands, immediate Boston south coast): Average last frost around April 15-25. Target planting from early to mid-May.

Always treat these dates as estimates. New England weather is famously variable, so soil temperature is your best guide.

The Critical Role of Soil Temperature and Conditions

Corn seed will not sprout reliably in cold soil. Even if it does, the seedlings will be weak and stunted. Cold, wet conditions also make seeds susceptible to fungal diseases and rot.

To warm your soil faster in the spring, consider using raised beds or covering your planting area with black plastic or dark mulch for 1-2 weeks before you intend to plant. This technique absorbs solar heat and can give you a head start.

Step-by-Step Spring Planting Schedule

4-6 Weeks Before Planting: Garden Preparation

Choose Your Site: Pick a spot with full sun (at least 6-8 hours daily). Corn is a heavy feeder.
Test and Amend Soil: Corn prefers a soil pH of 6.0 to 6.8. Work in several inches of well-rotted compost or aged manure to improve fertility and drainage.
Consider Succession Planting: To extend your harvest, plan to make 2-3 plantings about two weeks apart. This prevents all your corn from ripening at once.

1-2 Weeks Before Planting: Final Checks

Begin monitoring your soil temperature daily with a thermometer.
If the forcast looks warm and dry, you can prepare your planting rows or hills.
Ensure your seeds are ready. For a longer-season variety in cooler areas, you might consider starting seeds indoors in biodegradable pots 2-3 weeks before transplanting, but direct sowing is most common.

Planting Day: How to Sow Corn Correctly

Plant seeds 1–1.5 inches deep in heavier soils, and up to 2 inches deep in sandy soils.
Space seeds about 9–12 inches apart within the row.
Space rows 30–36 inches apart. Corn is wind-pollinated, so planting in blocks of at least 4 rows side-by-side (rather than one long row) is essential for good kernel development.
Water the seeds in thoroughly after planting.

After Planting: Early Care

Keep the soil consistently moist but not waterlogged until seedlings emerge, which typically takes 7-14 days depending on temperature.
Once seedlings are a few inches tall, thin them to the strongest plant every 12 inches.
Apply a thin layer of mulch to conserve moisture and suppress weeds once the soil is fully warm.

Choosing the Right Corn Variety for Massachusetts

Selecting a variety with a suitable “days to maturity” rating is key. This number, found on the seed packet, is from germination to harvest. In Massachusetts, aim for varieties that mature in 70-90 days to ensure a harvest before early fall frosts.

Early Season (~70-80 days): ‘Swift’, ‘Early Sunglow’, ‘Northern Xtra Sweet’. Good for zones 5b and 6a, or for your first succession planting.
Mid-Season (~80-90 days): ‘Bodacious’, ‘Kandy Korn’, ‘Silver Queen’. A reliable choice for most of the state.
Main Season (90+ days): Use these with caution in cooler areas, but they can work well in zone 7a or in a very warm, early summer.

Common Mistakes to Avoid

Planting Too Early: This is the number one error. Impatience leads to seed loss.
Inadequate Pollination: Planting in a single row or a too-small block results in poorly filled ears. Always plant in blocks.
Poor Soil Fertility: Corn needs nitrogen. Side-dress plants with a nitrogen-rich fertilizer when they are about knee-high (12 inches tall).
Ignoring Pest Timing: Corn earworm and European corn borer are common. Research organic or conventional controls timed for when silks appear.

FAQ: Planting Corn in Massachusetts

What is the absolute last date to plant corn in Massachusetts?

Count backwards from your area’s average first fall frost date. Use the “days to maturity” on your seed packet and add 2 weeks for cooling fall weather. For a 90-day corn with a mid-October frost, you’d need to plant by mid-July at the very latest, but earlier is safer.

Can I plant corn in late June?

Yes, planting in late June is often succesful for a fall harvest, especially with an early-maturing variety. Just ensure you can water consistently, as summer heat can dry out soil quickly.

Should I soak corn seeds before planting?

Soaking seeds for 4-6 hours before planting can speed up germination by a day or two, but it’s not necessary if your soil is adequately warm and moist. Avoid soaking if you’re planting into cool soil, as it can increase rot risk.

How do I protect early planted corn from a late frost?

If seedlings emerge and a late frost is forecast, you can cover them with a row cover, frost blanket, or even cardboard boxes overnight. Remove the covers during the day.

Why did my corn not produce full ears?

This is almost always due to poor pollination. Remember, corn relies on wind to transfer pollen from the tassels to the silks. Planting in a block (not a row) and avoiding pesticide use during tasseling are crucial steps. Also, hot, dry wind can dessicate silks, so adequate watering during this phase is important.

By following this schedule and focusing on soil warmth, you’ll give your Massachusetts corn crop the best possible start. A little patience in the spring leads to the sweet reward of fresh, homegrown corn in the late summer.