Massachusetts · zones 5a–7a
When to plant sweet corn in Massachusetts.
Sow between Apr 29 to Jul 29 in a typical year, keyed to Massachusetts's median last frost around Apr 22. Dates below are state medians; your ZIP code shifts them by days to weeks.
The 2026 windows
Sweet Corn dates for a typical Massachusetts season.
Direct sow
Apr 29 to Jul 29
Keyed to the ~Apr 22 last frost. Sow 1.5" deep, 12" apart.
Harvest
~75 days later
~1 lb per plant over ~1 weeks.
Massachusetts spans more than one climate: Zone 6 is the most common zone, but the state runs 5a to 7a. That's why the planner works from your ZIP code's frost dates, not your zone: mountain and coastal gardens in the same state can be three weeks apart.
Massachusetts growing notes
A breezy coastal plot needs its corn block even tighter.
Wind works against a thin row on the coast
Wind carries sweet corn's pollen from the tassel down to the silks below, and that mechanism works against a grower on Massachusetts' breezier coastal sites, where a steady onshore breeze can carry pollen past the row faster than it would drift through a sheltered inland yard. Planting corn as a block four rows across at minimum, never as one thin single row, keeps enough pollen falling inside the planting itself to fill ears properly even with wind working against it.
Inland gardens in a calmer spot don't need to overcorrect quite as much, but the same block shape still beats a single long row anywhere in the state; a poorly pollinated ear shows the result at harvest as bare, toothless patches clustered at the tip, where the last silks to emerge had the least chance of catching any pollen at all.
Keeping a supersweet variety honest on a crowded lot
Massachusetts' many small home gardens and diversified CSA farms often sit within a few hundred feet of a neighbor growing a different corn type, and a supersweet variety is the most cross-pollination-sensitive of any corn class, picking up starchy, tough kernels fastest when a different type tassels nearby during the same stretch of days.
Staggering planting dates by roughly 2 weeks between different corn types grown on the same property solves the problem without needing real distance, and treating any unfamiliar corn within a couple hundred feet as a cross-pollination risk, rather than assuming it's compatible, is the safer habit on a lot-sized Massachusetts property.
The single dose of oil that actually works
The corn earworm caterpillar does its damage out of sight: the moth lays a single egg on fresh silk, and by the time anyone would notice, the larva has already tunneled down toward the ear tip. Watching individual ears rather than scanning the whole patch at once matters here, since silks on different stalks emerge days apart even within one planting.
Once an ear's silks have gone from bright and moist to wilted and brown, one drop of mineral oil worked into the silk channel smothers eggs and any small larvae already inside without blocking pollen the way an earlier application would. Treating green, still-receptive silk instead leaves a bare, kernel-less tip that looks like earworm damage but is really a self-inflicted pollination failure.
In Massachusetts: watch for
The pests that find sweet corn here.
A middle-length season, about 181 frost-free days, means sweet corn overlaps corn earworm for a stretch each summer. Check plants every week or two and treat early.
Caterpillars feeding down in the tip of the ear.
Organic fix: A few drops of oil on the silk; Bt on the silks.
Broken tassels and frass-filled holes in the stalk.
Organic fix: Bt on young plants; cut and destroy stalks after harvest.
Clusters on the tassels and upper leaves.
Organic fix: Usually minor; insecticidal soap if heavy.
Fall armyworm
Ragged holes through the unfurling whorl leaves, with sawdust-like droppings down in the funnel.
Organic fix: Check whorls weekly before tassel; Bt or spinosad while the caterpillars are still small.
Cinnamon-brown powdery pustules breaking out on BOTH sides of the same leaf, lower leaves first, darkening as they age.
Organic fix: Water at the ground rather than overhead, and choose resistant varieties next season; sprays are rarely worth it.
Your season math: Massachusetts gives sweet corn about 181 frost-free days, and it needs roughly 75 days to a first harvest. That fits about 11 re-sown rounds across the season, so you can keep it coming instead of picking once.
Planting sweet corn in Massachusetts: questions
When should I plant sweet corn in Massachusetts?+
In a typical Massachusetts year, sow sweet corn between Apr 29 to Jul 29, keyed to the state's median last frost around Apr 22. Your exact dates shift with your ZIP code and microclimate.
What USDA zone is Massachusetts?+
Massachusetts spans zones 5a–7a, mostly zone 6. But frost dates, not zones, set planting time. The free planner uses your ZIP code's actual frost dates.
How many sweet corn plants do I need?+
Depends who you're feeding. The crop page has exact counts per household size, or the free planner does the math for your family in about 60 seconds.