Vegetable · Brassicaceae
Mustard Greens
Brassica juncea
Timed to the cool shoulders of the year, mustard greens bring peppery leaves to the table within the month.
Full sun
Every 2–4 days
39–75°F · 4–24°C
30–50 days
Overview
Mustard greens are a fast leafy vegetable in the cabbage family, grown for their peppery, slightly spicy leaves. With roots in Asia and a home now in temperate gardens the world over, the plant slips as easily into a Southern row as a Northern raised bed. Give it cool weather and it travels from seed to plate faster than almost anything you might plant, which makes it a fine anchor for the cool-season table.
Its speed sets the rhythm of the garden. A single sowing can reach a first cutting in 30 to 50 days, and taking the outer leaves young keeps the center sending up fresh growth for the kitchen. Left to fill out, a plant stands about 12 to 18 inches (30 to 45 cm) tall, a tidy presence in a raised bed or a cool-weather container by the door, though many gardeners sow it close and gather a steady patch of baby leaves instead.
Heat is the one thing that unsettles it. Warm weather and long days push the plant to send up a flower stalk, and once it bolts the leaves turn tough and sharply bitter. Sow it for the cool ends of the year, keep the soil evenly moist, and the flavor stays bright and clean from the bed to the plate.
Care
The short version: full sun and cool weather, soil kept evenly moist so the flavor stays mild, rich ground worked with compost, and a timely harvest before summer heat turns the leaves bitter.
Light
Mustard greens are at their best in full sun, yet they take partial shade in stride, a grace that tells as the season warms. A little afternoon shade in late spring buys a stretch of extra time before heat coaxes the plants to bolt.
Water
Keep the soil evenly moist and water early so the leaves dry before nightfall, which holds fungal disease at arm's length. Let the plants dry out and rebound and the flavor turns unpleasantly sharp and spicy, so keep the rhythm steady.
Soil
Set them into rich, well-drained ground worked with plenty of organic matter. A pH near 6.0 to 6.8 suits them best, and though they take soil up toward neutral, it is the good fertility that carries the fast leaf growth you are after.
Temperature
This is a cool-season grower, most content between 39°F and 75°F (4°C to 24°C). It takes a light frost in stride, which can even sweeten the leaves, but warmth at the top of that range is what tips it into bolting.
Humidity
Average humidity, somewhere near 40% to 70%, is all it asks. Airflow counts for more than any exact figure, since crowded, damp leaves invite the fungal troubles that early watering is meant to keep away.
Feeding
Work a nitrogen-rich balanced fertilizer into the bed at planting to carry the fast leaf growth. A light nitrogen side-dressing partway through keeps the leaves coming, though a measured hand is best, since too much soft growth draws aphids.
Pruning
Cut the outer leaves young and often, and the plant answers with tender new growth from the center. Once it begins to bolt, pinch out the flower stalk, though by then the leaves have usually turned strong and bitter.
Repotting
Not applicable; direct-sown as a fast garden crop, not container-grown/repotted.
Size & spacing
Plants reach about 12 to 18 inches (30 to 45 cm) tall and roughly as wide, a neat footprint for a bed or a container. Give full-size plants around 12 inches (30 cm) of room, or sow closer and harvest the patch as baby leaves.
When to plant
Mustard greens belong to the cool shoulders of the year and have no patience for heat. Sow the first round in early spring, about three weeks before your last frost, then sow again in late summer for a fall harvest. Cut the leaves young, and bring the whole crop in before summer warmth coaxes it to bolt.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Sow: 3-4 weeks before the last spring frost, or direct-sow
- Plant: Early spring (about 3 weeks before last frost) and again in late summer for a fall crop; a cool-season vegetable.
- Harvest: Cut leaves young at about 4-6 weeks; harvest the whole plant before summer heat causes it to bolt.
Hardiness
USDA hardiness zones: 2–11
Temperature: down to -46°C
Troubleshooting
Most of what troubles mustard greens shows first on the leaves, and a quick daily pass through the bed catches it early. Match what you notice below to its cause, then step in while the planting is still worth the effort.
Young plants folding as the roots rot below
Seedlings that wilt and fold with no cause in sight are often quietly undone by cabbage maggots, white larvae tunneling through the roots below the surface. Anything already lost is best pulled and cleared away. A row cover set down at sowing turns back the egg-laying flies, and leaving fresh manure out of the bed removes what first draws them near.
Fix:
- Remove and destroy infested plants
- Protect remaining plants with row covers
A fine scatter of pinholes across the leaves
A fine stipple of pinprick holes across the foliage is the mark of flea beetles, small dark insects that scatter the moment a hand comes near. The youngest seedlings show the wear first. Draped over the bed at sowing, a floating row cover keeps them out, and a planting that grows on steadily carries the light damage without missing a beat.
Fix:
- Cover seedlings with floating row cover
- Apply kaolin clay or labeled insecticide if damage is heavy
- Maintain vigorous growth so plants outgrow light feeding
Ragged holes chewed through the leaves
Torn, ragged holes and scattered dark droppings betray cabbageworms and cabbage loopers, green caterpillars that all but disappear against the leaves. Lifting off the ones you find works, and a Bt spray answers a heavier turn. The lasting remedy is netting, which keeps the parent moths from ever laying their eggs.
Fix:
- Handpick caterpillars
- Apply Bacillus thuringiensis (Bt)
- Use row covers to exclude egg-laying moths
A too-soon flower spike and leaves turned coarse and sharp
A stalk rising from the center and a sharpening on the palate signal bolting, brought on by warm weather and longer days. The turn does not reverse, so gather the leaves before they lose their charm. A cool spring or fall planting, a little afternoon shade as the season warms, and a bolt-resistant type each buy more time on the table.
Fix:
- Harvest promptly before flavor degrades; bolting cannot be reversed
Puckered leaves wearing a sticky sheen and tiny insects
Curling tips and a faint sticky sheen point to aphids gathered along the undersides. A firm rinse of water sends most of them packing, insecticidal soap tidies up any that return, and lady beetles keep watch afterward. A lighter hand with nitrogen helps as well, since the soft, tender flush that heavy feeding brings is just where they settle.
Fix:
- Dislodge with a strong spray of water
- Apply insecticidal soap
- Encourage lady beetles and other natural predators
Toxicity
Mustard greens sit easily in a home shared with animals, a food crop and a safe one. No part of the plant poisons cats, dogs, or other pets, and the leaves themselves belong on the table. The single note worth keeping is for livestock grazed heavily on the foliage, where the goitrogens common to all brassicas can gather over time.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats None
A worry-free companion for the household cat. The ASPCA leaves mustard greens off its list of plants toxic to cats, so a curious nibble means nothing.
Dogs None
Nothing here troubles a dog that samples a leaf, though a generous helping of any leafy green may leave the stomach briefly unsettled.
Horses Safe
A horse may graze it in ordinary amounts with ease, free of any compound that would pose a risk.
Rabbits Safe
A welcome nibble for rabbits in moderation, best folded in slowly beside hay and other greens rather than all at once.
Livestock Mild
Sound, safe forage, though steady day-after-day grazing on the brassica foliage lets goitrogens gather and lean on the thyroid. It belongs as one thread in a varied diet.
Birds Safe
An easy pleasure for birds, with backyard hens pecking the leaves and taking the greens as a wholesome treat.
People Safe
A kitchen staple and safe to enjoy, the peppery leaves welcome on the plate cooked or raw, with no part of the plant set aside.
Like other brassicas the foliage contains glucosinolates/goitrogens; this is mainly a dietary concern for livestock grazed heavily on it, not a household-pet poisoning hazard.
Varieties
Mustard greens arrive in smooth, curled, and red-tinged forms, and a few names return season after season. These are the ones worth setting to memory.
Florida Broadleaf
A quick Southern classic that unfurls large, smooth, broad green leaves ready for the earliest young cuttings.
Southern Giant Curled
Its frilled, heavily curled bright green leaves weather a frost with more poise than the flat-leaved kinds.
Giant Red
Chosen as much for its looks as its bite, it wears purple red tinged leaves over a strong peppery flavor.
Tendergreen
A mild, quick smooth-leaf sort often grown as a spinach-mustard for gentler eating at the table.
How to propagate
Mustard greens are grown straight from seed, and few crops repay the effort so quickly or so surely.
SeedEasy
Direct-sow in early spring and again in late summer for a fall crop · Germinates in about 5-10 days and seedlings establish within roughly 2 weeks
Few crops reward a gardener so quickly from seed. Sown shallow into cool, moist soil in early spring, and again in late summer for a fall crop, mustard greens rise in 5 to 10 days with seedlings settled in about two weeks. Thin them to roughly 12 inches (30 cm) apart for full-size plants, or leave the sowing close for a generous cut-and-come-again patch.
Myths
Mustard greens pose a poisoning danger to cats and dogs.
Brassica juncea is an everyday edible vegetable, and the ASPCA does not name it toxic to cats or dogs. The goitrogen concern rests with livestock grazed heavily on the foliage, not with a pet that samples a leaf in passing. For a household with pets, mustard greens are safe.
The warmth of midsummer suits mustard greens best.
This is a cool-season crop that comes into its own across spring and fall. Summer heat only hurries it to bolt, and the leaves lose their charm to a harsh, bitter edge once it does. Reserve the sowings for the cool ends of the year.