Mustard greens are the fast, fiery leafy green: sow them and within six weeks you have a crop of peppery, pungent leaves that liven up salads, stir-fries and braises like nothing else in the garden. They are the green for cooks who like a bit of bite.
They take just 40–50 days to mature and they are hardy, so they are a spring and autumn crop, sown in succession for a continuous supply. They grow fast, they bolt fast in heat, and they are at their best picked young.
Mustard Greens at a glance
| Growing factor | What mustard greens need |
|---|---|
| Sun | full sun |
| Soil pH | 6.0–7.5 |
| Days to germination | 7–10 |
| Days to maturity | 40–50 |
| Spacing | 6–12 inches |
| Water needs | moderate |
| Cold tolerance | hardy |
| Family | Brassicaceae |
Starting seeds
Mustard Greens are direct-sown outdoors — they do not transplant well, so start them where they will grow. Sow the seed at the depth on the packet, in rows spaced for the mature plant, and keep the seedbed evenly moist until seedlings appear, which takes 7–10 days.
Because the seed goes straight into the garden, timing matters more than with transplants: sow too early into cold, wet soil and germination stalls, sow too late and the plants run out of season. Use our frost-date calculator and the hardiness-zone finder to place your sowing window, and check your local extension service for the dates that fit your area.
Mustard greens are direct-sown, with germination in 7–10 days. Sow thinly in shallow drills, barely covering the seed, and keep the soil moist until seedlings appear. Sow in early spring in Zones 3–6, in late winter to early spring and again in late summer in Zones 7–9, and in autumn and winter in Zones 10–11; in frost-free Zones 11–13 sow in the cool season. For a continuous supply, sow a short row every two to three weeks — a big sowing all matures at once and bolts together.
Transplanting and planting out
Mustard greens are not transplanted — they are sown where they will grow, and they grow too fast for transplanting to be worth it. Thin seedlings to 6–12 inches apart once they are a few inches tall, and eat the thinnings in salads. Because the plants are fast and shallow-rooted, keep the bed weed-free by hand while they establish.
When you set plants out, space them 6–12 inches apart — that spacing is what the mature plant needs, and crowding is one of the commonest causes of small harvests. Our plant-spacing calculator works out how many plants fit your bed, and the square-foot garden planner can lay the bed out for you. Harden seedlings off for a week before planting out, moving them outside for longer each day, and plant on a cloudy day or in the evening so they do not wilt in their first hours outdoors.
Soil and feeding
Mustard greens want fertile, moisture-retentive soil at pH 6.0–7.5, with compost dug in before sowing. They are quick feeders, so a little balanced fertiliser at sowing time is enough — they will be harvested before they need a second feed. Like all brassicas, they should not follow another brassica in the same bed. A fine, crumbly seedbed gives the best germination.
Aim for a soil pH of 6.0–7.5 — a simple soil test will tell you where you stand, and garden lime or sulfur can nudge pH up or down over a season. Feed lightly and steadily rather than in one heavy dose: too much fast nitrogen late in the season pushes leafy growth at the expense of the part you eat. Our fertiliser calculator works out amounts for your bed size, and the raised-bed soil calculator and soil-volume calculator tell you how much mix a new bed needs. A mulch layer after planting keeps the soil moist and cool and feeds the soil as it breaks down.
Watering
Water needs are moderate: keep the soil evenly moist through the growing season, watering deeply when the top inch or two dries out. Deep, infrequent watering builds deeper roots than a daily sprinkle, and it keeps the plants steady through dry spells.
Water needs are moderate, but mustard greens must not dry out — drought makes them bolt and turns the leaves hot and tough. Water little and often, keeping the soil moist, especially in the first weeks after germination. Mulch between rows to hold moisture in, and water in the morning so the leaves dry during the day.
Water at the base of the plant, in the morning, so the leaves dry quickly and the water reaches the roots instead of evaporating off the surface. A soaker hose or drip line is ideal. Our watering calculator gives a starting point for your bed size and soil, and the watering schedule generator can build a routine around it. Mulch is your best friend here: a few inches of straw or shredded leaves cuts evaporation and keeps moisture even between waterings.
Sunlight and temperature
Mustard greens need full sun for the fastest growth, though they tolerate light shade — and in a hot spring, a little afternoon shade slows bolting. They are hardy, so spring and autumn sowings take light frosts in their stride, and a light frost sweetens the leaves. In Zones 8–10 they grow through winter; in frost-free Zones 11–13 grow them in the coolest months, since heat makes them bolt and turns them fiercely hot.
This crop is rated hardy for cold tolerance, so plan your season around that: hardy and frost-tolerant crops can be sown and harvested around frosts, while tender crops need warm soil and frost-free nights. Our sunlight calculator can check whether your spot gets enough sun through the season, and the hardiness-zone finder will confirm your zone. If your summers run very hot, afternoon shade or a shade cloth can keep a cool-season crop productive for a few extra weeks.
Pests and diseases
Mustard greens attract the usual brassica pests, and the fast growth means damage shows quickly. The ones to expect are cabbage worms, aphids, flea beetles and slugs.
- Cabbage Worms — green caterpillars that chew holes in leaves. Pick them off by hand and grow under fine mesh.
- Aphids — cluster on young leaves. Wash them off with water and encourage ladybirds.
- Flea Beetles — tiny beetles that pepper young leaves with shot-holes. Keep seedlings covered and watered — vigorous plants outgrow the damage.
- Slugs — chew young seedlings in damp weather. Pick them off at dusk and keep the bed clear of debris.
Inspect plants weekly, especially the undersides of leaves, and act early — a small problem caught in time is a hand-picked handful of pests, while a late one can cost the crop. Row cover keeps many flying pests off young plants, and healthy, well-watered plants resist attack far better than stressed ones. If you need help identifying what you are seeing, our pest-identifier helper and plant-disease checker walk through the symptoms.
Companion plants
Mustard greens grow well with marigolds, basil, onions and lettuce. They are often used as a trap crop — flea beetles prefer mustard to other brassicas, so a row of mustard can draw pests away from your cabbages. Lettuce and mustard share a cool season and a bed happily. As brassicas, they should not follow another brassica in the same ground.
Good companions for mustard greens include:
- Marigolds
- Basil
- Onions
- Lettuce
Our companion-planting finder can suggest more pairings for your bed plan. As a general rule, avoid planting members of the same family (Brassicaceae) in the same spot year after year — rotate beds so soil-borne problems do not build up.
Harvesting
Start picking outer leaves once the plant is big enough, from about 40 days after sowing, or cut the whole plant when it reaches a good size. Young leaves are mild and good raw in salads; older leaves are hotter and better cooked. Pick little and often, and always before the plant bolts — once it flowers, the leaves turn tough and bitter. In a good spring, a sowing gives you three or four pickings.
Expect the crop to be ready about 40–50 days after sowing, though weather and variety shift that window by a week or two either way. Our harvest-date calculator works out your expected harvest date from your sowing date, and the vegetable-yield estimator can estimate how much a bed should produce. Harvest in the morning when plants are cool and crisp, and use a sharp knife or secateurs rather than tearing, which damages the plant and invites disease.
Common problems and fixes
| Problem | Likely cause | Fix |
|---|---|---|
| Bolting to seed | heat or long days | Sow in cool weather; pick young and often. |
| Leaves too hot to eat | drought or hot weather | Water well and pick young leaves. |
| Flea beetles peppering the leaves | beetles attacking young plants | Grow under fine mesh and keep plants watered. |
Bolting to seed
Likely cause: heat or long days Mustard greens bolt fast in heat and long summer days. Sow in spring and autumn, not midsummer, and pick the leaves young — a bolted plant is finished, so sow the next row.
Leaves too hot to eat
Likely cause: drought or hot weather Mustard heat increases with drought and heat. Keep the soil moist, pick young leaves for salads, and cook the older, hotter leaves, which mellows them.
Flea beetles peppering the leaves
Likely cause: beetles attacking young plants Tiny shot-holes in young leaves are flea beetles. Cover seedlings with fine mesh and keep them growing fast — vigorous plants outgrow the damage, and mustard is often used to draw flea beetles away from other crops.
Frequently asked questions
When do I harvest mustard greens?
From about 40 days after sowing, picking outer leaves or cutting the whole plant. Young leaves are mild raw; older leaves are hotter and better cooked.
Why did my mustard greens bolt?
Heat or long days — they are a cool-season crop and bolt fast in summer. Sow in spring and autumn, and pick young and often.
Why are my mustard greens so hot?
Drought and heat increase the bite. Water well, pick young leaves, and cook the older ones — cooking mellows the heat.
Can I grow mustard greens in a pot?
Yes — they are ideal for containers. Sow thickly in a wide pot, keep them watered, and cut the leaves young.
How often should I sow mustard greens?
Every two to three weeks in spring and autumn, so you always have a young row coming ready. They mature in just 40–50 days.