How to Grow Mustard Greens

Timing: two short windows

Spring mustard goes in early — about three weeks before the frost-free date per Illinois Extension, with a second sowing three weeks later — and the race is to harvest before warmth ruins it; Clemson notes spring plantings may bolt as temperatures rise.

The fall window is the better one: sow from midsummer on, and the crop matures into cooling weather, which keeps leaves mild and delays bolting. Fall plantings tolerate frost, though a hard freeze can damage them.

At 25 to 50 days to maturity, short succession sowings beat one big planting — a fresh row every few weeks gives a steady supply of young leaves instead of one glut of aging ones.

Sowing and harvesting for regrowth

Sow seed 1/3 to 1/2 inch deep and thin seedlings to 3 to 5 inches apart. Thinnings are dinner.

You can cut entire plants, or pick individual outer leaves as they grow and let the plant keep producing from the center — the same cut-and-come-again approach used for other leafy greens. Young leaves 4 to 5 inches long are mild enough for salads; larger leaves are cooking greens.

Keep plants growing fast with steady moisture — slow, stressed mustard is hot-flavored and quick to bolt.

Bolting: recognize it, don't fight it

Mustard is wired to flower under warm weather and lengthening days. Once a flower stalk starts, leaf production stops and flavor turns harsh — no amount of watering brings the crop back.

Illinois Extension's advice is blunt: pull and compost the plants when hot weather arrives, preferably before flower stalks develop. Letting bolted mustard stand also risks it seeding around the garden.

Treat that as the calendar working, not failure: clear the spring crop, use the bed for something summer-proof, and sow mustard again from midsummer for the better fall harvest.

Sources

Reviewed 2026-07-18. We cite university Extension, government, and established horticultural sources — and never invent pesticide rates or dangerous treatments.

• Illinois Extension — Mustard (Home Vegetable Gardening) — Plant early in spring, 3 weeks before the frost-free date, and again 3 weeks later; plant from midsummer on for fall harvest, and fall plantings are usually of higher quality; sow 1/3 to 1/2 inch deep and thin to 3-5 inches; cut the entire plant or pick individual leaves as they grow; mustard flowers in warm weather and long days — pull and compost when hot weather arrives, preferably before flower stalks develop.
• Clemson Cooperative Extension HGIC — Arugula, Kale, Mesclun, Mustard, and Swiss Chard — Mustards reach maturity between 25 to 50 days from sowing depending on cultivar; spring plantings may bolt with warmer temperatures; fall plantings are tolerant of frost but may be damaged by a hard freeze.

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