How to Grow Sweet Corn: Block Planting, Variety Types, and the 60-Minute Sweetness Window
Nothing says summer like eating fresh corn on the cob. And you can grow it even if you're limited on space. Here's how to get started.
Quick Reference: Growing Sweet Corn
- Plant in BLOCKS, not rows. 4×4 or larger. Wind-pollinated, needs multiple plants close together.
- 3 variety types. su (sugar) old-school sweet; se (sugary enhanced) sweeter, slower decline; sh2 (super sweet) sweetest, stays sweet longest.
- Soil 60 F minimum. Phenology: oak leaves squirrel-ear size.
- Spacing. 8 to 12 inches between plants, 30 to 36 inches between rows.
- Pick at first silk-browning, eat within 60 minutes. Sweetness drops 50 percent in 1 hour for su varieties.
On this page
Related Almanac guides
Sources cited in this guide
Sweet corn is the highest-payoff home garden crop because grocery-store corn cannot match the flavor. Sweetness drops 50 percent within an hour of picking for traditional varieties. This guide is the block-planting layout that solves the pollination problem, the three modern variety types (sugar, sugary enhanced, super sweet), and the harvest window that determines whether you get sweet corn or starchy corn.
Why You Plant Corn in Blocks (Not Long Rows)
Per UMN Extension’s growing sweet corn guidance.
- Wind-pollinated. Pollen falls from male tassels (top of plant) onto silks of female ears below. Each silk strand pollinates one kernel.
- Why rows fail. A single long row receives pollen on only one side. Poor pollination = missing kernels.
- Why blocks work. A 4×4 or larger square ensures pollen falls on all surrounding plants. Full pollination = full ears.
- Minimum block size. 4 plants by 4 plants. Larger is better.
- Isolation. If growing multiple corn varieties, separate by at least 250 feet or stagger sowing by 14 days to prevent cross-pollination.
The 3 Sweet Corn Variety Types
Per Cornell Cooperative Extension sweet corn variety research.
- su (sugary, normal sugar). Old-school sweet corn. Highest sweetness at pick, drops 50 percent within an hour. Examples: Country Gentleman, Stowell’s Evergreen.
- se (sugary enhanced). Sweeter than su, slower decline in sugar. Tender kernels. Examples: Bodacious, Silver Queen.
- sh2 (super sweet, shrunken-2). Sweetest of all. Sugar holds 5 to 14 days. Tougher kernel. Examples: Honey Select, Mirai.
- Choose: sh2 for storage and shipping, se for fresh eating in 1 to 3 days, su for old-fashioned flavor (must be eaten within an hour).
How to Plant Sweet Corn (Detail)
Below are the original detailed sections on planting sweet corn and tips.
How To Plant Sweet Corn
Start: Plant seeds directly outdoors, 2 weeks after your last frost. Plant in rows 2-3′ apart. Space seeds 5-6″ apart and cover with 1” of soil. When seedlings are 3-5” tall and healthy, thin to stand 1’ apart.
Water: Corn grows fast and needs plenty of water, 1-2” inches per week. During dry times, one or two deep soakings per week is more effective than several lighter waterings.
Soil: Corn prefers a well-drained, sandy loam. pH 5.8-6.8
Light: Full sun.
Fertilize: Corn is a heavy feeder and needs ample fertilization. Using compost or an all-purpose fertilizer at planting will get the corn off to a good start, but the corn will soon deplete the nutrients in the soil. Side dress the plants with a nitrogen-rich fertilizer when the plants have about ten leaves each and again when silk first appears on the cobs.
Harvest: Ears are ready to harvest about 20 days after the silks emerge. Pierce a kernel to check for ripeness. The juice should be milky. Watery juice means the corn is not yet ripe; creamy juice is overripe and won’t be as sweet. Firmly grip the ear and twist downward to harvest. Be careful not to damage the stalk as that may result in the second ear not developing.
Notes: Make sure to devote a large enough space for your corn patch, at least 10’ by 10’, as corn is wind-pollinated. And get the seeds started as soon as possible.
Corn Recipes, Tips & Folklore
Delicious and Different Corn on the Cob Recipes
Cooking Vegetables: When Should You Boil The Water?
Weather Lore: Knee-High by the Fourth of July
Growing Sweet Corn FAQ
How do you plant sweet corn?
Direct sow 1 inch deep in blocks (not long rows) of at least 4×4. 8 to 12 inches between plants, 30 to 36 inches between rows. Soil should be 60 F minimum (phenology: oak leaves squirrel-ear size). Harvest 60 to 100 days from sowing depending on variety.
Why do you plant corn in blocks?
Corn is wind-pollinated. Pollen from tassels (male flowers at top) falls onto silks (female flowers on the ear). A long single row only receives pollen from one direction, missing many kernels. A 4×4 or larger block ensures pollen reaches every silk, producing full ears.
When should you pick sweet corn?
First silk-browning is the signal. Squeeze a kernel; milky liquid means ready. Clear liquid means too early; doughy means too late. Pick in the morning when sugars are highest. Eat within an hour for su varieties, within a day or two for se, within a week for sh2.
What is the difference between su, se, and sh2 sweet corn?
Sweetness level and shelf life. su = traditional sweet (highest flavor at pick, drops 50 percent in 1 hour). se = sugary enhanced (sweeter, slower decline). sh2 = super sweet (sweetest, holds 5 to 14 days). Modern varieties are mostly se and sh2.
How tall does sweet corn grow?
5 to 9 feet depending on variety. Most modern sh2 hybrids stay 6 to 7 ft. Heirloom su varieties can reach 9+ ft. Plant in the back of the bed or where shade does not matter; corn shades whatever is east or west of it.
This article was published by the Staff at FarmersAlmanac.com. Any questions? Contact us at questions@farmersalmananac.com.
- Farmers' Almanac Staff
- Farmers' Almanac Staff
- Farmers' Almanac Staff
- Farmers' Almanac Staff
When do I plant in Imperial county,Ca winter crops what types in my planters?
When do I plant winter corn and winter crops in Imperial county,Ca
When do I plant sweet winter corn ?
Is May 2 a good time to plant sweet corn?
I want to make sure the ear worms don’t eat my corn, what can I use to keep this pest out of my ears of corn?
Sevin dust when you see the silk