In zone 7, sow sweet corn directly in the garden from April 24 to May 1, one to two weeks after your last spring frost, once the soil is at least 50 °F (65 °F for supersweet types). Expect ripe ears in about 80–100 days, from around July 13.
Sweet corn dates for your ZIP code
Planting times based on university extension guidance (UNH, Cornell, Purdue, Minnesota, Nebraska and UMass Extension). Frost dates from NOAA 1991–2020 U.S. Climate Normals, nearest weather station. Zones derived from the 2023 USDA Plant Hardiness Zone Map data (PRISM Climate Group, Oregon State University). This is not the official USDA Plant Hardiness Zone Map.
Sweet corn timing in zone 7
| Task | When |
|---|---|
| Sow outside | April 24 – May 1 |
| First harvest | July 13 – August 9 |
| Sow again | Every 7–10 days for a longer harvest |
| Side-dress with nitrogen | When plants are 15–18 inches tall |
| Water | About 1 inch a week, especially before silks appear |
Most of zone 7 sees its last spring frost between April 10 and April 26, with a typical date of April 17. Corn seed rots in cold, wet soil, so the soil temperature matters more than the calendar date. The tool above uses the weather station closest to your ZIP code.
Why sweet corn waits for warm soil
Sweet corn is a warm-season crop. Frost damages it, and its seed rots in cold, wet soil. It germinates best at soil temperatures of 60–85 °F and needs at least 50 °F, or 65 °F for supersweet varieties. That is why it is sown one to two weeks after the last spring frost.
Best sweet corn varieties for zone 7
Zone 7 has time for early, mid-season and late sweet corn. Pick a sweetness type first:
- Sugar-enhanced (se): Ambrosia, Peaches and Cream, Sugar Buns, and the white varieties Silver King and Silver Princess. No isolation needed.
- Supersweet (sh2): Illini Gold and other extra-sweet types. Sow once the soil is 65 °F, and keep them apart from other corn.
- Standard (su): Silver Queen and Merit, the classic corn flavor.
How to plant sweet corn
- Sow directly in the garden, about 1 inch deep in early plantings and 1–2 inches later in the season.
- Space seeds 8–10 inches apart in rows 2½–3 feet apart.
- Plant in a block of at least three or four short rows for good pollination.
- Fertilize before planting, then side-dress with nitrogen when plants are 15–18 inches tall.
- Water about an inch a week, especially in the two weeks before silks appear.
Zone 7 sweet corn tips
- Plant in blocks. Several short rows side by side pollinate much better than one long row.
- Water before the silks. The two weeks before the silks appear are when corn most needs water: about an inch a week.
- Feed twice. Work fertilizer into the soil before planting, then side-dress with nitrogen when plants are 15–18 inches tall.
- Isolate supersweet corn by distance, or plant it so it tassels at a different time from other corn.
Harvesting sweet corn
Sweet corn is ready about 20 days after the first silks appear, when the silks are dry and brown, the husks are still green and the ears feel plump. Pull back a husk to check: the kernels should be full and milky. Pick in the cool of early morning and refrigerate right away, because the sugar turns to starch quickly in warm temperatures.
Sweet corn planting dates in nearby zones
See dates for every zone on the sweet corn planting guide, or build a full schedule with the planting calendar.
Frequently asked questions
Is it too late to plant sweet corn in zone 7 in May?
Usually not. Corn needs 80–100 days, and in zone 7 your first frost comes around October 23. Count back from that date and choose a variety that fits.
When is sweet corn ready to pick?
About 20 days after the silks first appear, when the silks are dry and brown, the husks are still green and the kernels squirt milky juice when pressed.
What do su, se and sh2 mean on sweet corn seed?
They are sweetness types. Standard (su) is the classic flavor, sugar-enhanced (se) is sweeter and holds its sugar longer, and supersweet (sh2) is the sweetest but needs warm soil and must be kept apart from other corn.
Why plant sweet corn in blocks?
Corn is pollinated by wind, and each kernel needs its own grain of pollen. A block of several short rows catches pollen much better than a single long row.
How long does sweet corn take to grow?
About 80–100 days from sowing, depending on the variety.
Sources. Planting dates use the median frost dates of each USDA zone, calculated from NOAA climate data for every ZIP code in the zone.