Vegetable · Brassicaceae
Mustard Greens
Brassica juncea
Sow it in the cool of spring or fall and mustard greens give you peppery leaves in barely a 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. The plant traces back to Asia and now feels at home in temperate gardens the world over, thriving just as easily in a Southern row or a Northern raised bed. Give it cool weather and it travels from seed to plate faster than almost anything else you might plant, which makes it a lovely confidence-builder.
Speed really is the joy of it. A single sowing can reach a first cutting in 30 to 50 days, and you are welcome to take the outer leaves young while the center keeps sending up fresh growth. Let a plant fill out and it reaches about 12 to 18 inches (30 to 45 cm) tall, but many gardeners tuck them in close and simply gather a steady patch of tender baby leaves.
The one thing that truly bothers mustard greens is heat, and knowing that alone puts you ahead. 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 you will find the flavor stays bright and clean.
Care
The short version: give it full sun and cool weather, keep the soil evenly moist so the flavor stays mild, work in some rich compost, and gather your leaves before summer heat turns them bitter.
Light
Mustard greens do best in full sun, yet they take partial shade in stride, which is a real help as the season warms. A touch of afternoon shade in late spring buys you a little more time before the heat coaxes the plants to bolt.
Water
Aim to keep the soil evenly moist and water early so the leaves dry before nightfall, which keeps fungal disease at bay. Try not to let the plants dry out and bounce back, since that moisture stress turns the flavor unpleasantly sharp and spicy.
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, though they cope with soil up toward neutral, and that good fertility is what drives the fast leaf growth you are hoping for.
Temperature
This is a cool-season grower, happiest between 39°F and 75°F (4°C to 24°C). It handles a light frost without trouble, which can even sweeten the leaves, but warmth near the top of that range is what sets it bolting.
Humidity
Average humidity, somewhere around 40% to 70%, is all it asks of you. Good airflow matters more than any exact figure, since crowded, damp leaves invite the very fungal problems that watering early helps you avoid.
Feeding
Work a nitrogen-rich balanced fertilizer into the bed at planting to fuel that fast leaf growth. A light nitrogen side-dressing partway through keeps the leaves coming, but go gently, because too much soft growth tends to draw aphids.
Pruning
Cut the outer leaves young and often, and the plant thanks you with tender new growth from the center. Once it begins to bolt, pinch out the flower stalk, though by that point 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. Give full-size plants around 12 inches (30 cm) of room, or sow a little thicker and harvest the whole patch as baby leaves.
When to plant
Mustard greens are a cool-season crop with no fondness for heat, and timing is the one thing worth getting right. Sow your 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 try to get the whole crop in before summer warmth nudges 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 mustard-green troubles turn up right on the leaves, and a quick daily glance is usually enough to catch them early. Match what you are seeing below to its cause, then step in while the planting is still well worth saving.
Young plants wilting from damaged roots below
When seedlings droop and topple for no reason you can see, cabbage maggots are often at work, and these white larvae tunnel through the roots down in the soil. The gentlest thing you can do is pull and get rid of any plant that is already lost so the rest stay safe. A row cover set down at sowing keeps the egg-laying flies away, and holding off on fresh manure removes the smell that invites them.
Fix:
- Remove and destroy infested plants
- Protect remaining plants with row covers
Tiny pinprick holes scattered across young leaves
If you spot a scatter of tiny holes, take heart, because flea beetles are the likely culprit and they are easy to manage. These little dark hoppers jump off the moment your hand comes near, and it is the young seedlings that feel it most. Lay a floating row cover over the bed at sowing and keep your plants growing along nicely, and a healthy plant will simply shrug the nibbling off.
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
Torn holes and dark droppings on the foliage
Large ragged holes paired with dark droppings point to cabbageworms and cabbage loopers, green caterpillars so well hidden they melt into the leaves. Don't worry, you can pick off the ones you find by hand and use a Bt spray if they get numerous. The kindest long-term answer is a layer of netting that stops the parent moths from laying eggs in the first place.
Fix:
- Handpick caterpillars
- Apply Bacillus thuringiensis (Bt)
- Use row covers to exclude egg-laying moths
An early flower stalk and leaves gone harsh
When a stem rises up the middle and the taste sharpens, your plant is bolting, nudged along by warm weather and lengthening days. This one you cannot undo, so gather the leaves while they are still sweet and try not to feel discouraged. Next time, plant into the cool of spring or fall, shade the bed as the days heat up, and pick a bolt-resistant type to give yourself the easiest run.
Fix:
- Harvest promptly before flavor degrades; bolting cannot be reversed
Curling leaves with a sticky film and huddled insects
Crumpled leaf tips and a tacky coating usually mean aphids have gathered on the undersides, and you can clear them without much fuss. A firm blast of water knocks most of them off, and a follow-up with insecticidal soap handles any stragglers while lady beetles pitch in. It also helps to lighten up on nitrogen, since the soft, tender growth it brings is just what aphids love to settle on.
Fix:
- Dislodge with a strong spray of water
- Apply insecticidal soap
- Encourage lady beetles and other natural predators
Toxicity
You can rest easy with mustard greens around the house, since this is a food crop and a safe one. No part of the plant will poison cats, dogs, or other pets, and the leaves are good to eat besides. The only real note is for livestock grazed heavily on the foliage, where the goitrogens common to all brassicas can add up over time.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats None
You can relax here, because the ASPCA does not list mustard greens among plants toxic to cats, so a curious nibble does no harm at all.
Dogs None
No need to fret if your dog crops a leaf, as it comes to no harm, though a very big helping of any leafy green might leave a tummy a little unsettled.
Horses Safe
Perfectly fine for a horse to graze in normal amounts, with none of the toxic compounds that would put it at risk.
Rabbits Safe
Rabbits do well with the leaves in moderation, so ease them in bit by bit alongside plenty of hay and other greens rather than all in one go.
Livestock Mild
This makes good, safe forage, but keep in mind that heavy grazing day after day on the brassica foliage can act as a goitrogen and press on the thyroid, so let it be just one part of a varied diet.
Birds Safe
Nothing to worry about, as backyard hens happily peck at the leaves and the greens make a wholesome treat for them.
People Safe
Good to eat and welcome on the table, with the peppery leaves enjoyed cooked or raw and no part of the plant that you need to avoid.
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 come in smooth, curled, and red-tinged forms, and a handful of names keep coming up as reliable choices. These are the ones worth getting to know.
Florida Broadleaf
A quick Southern favorite whose large, smooth, broad green leaves are ready for you to start cutting while they are still young.
Southern Giant Curled
Its frilled and heavily curled bright green leaves stand up to a frost more gracefully than the flat-leaved kinds.
Giant Red
Prized for its looks as much as its bite, it carries purple red tinged leaves that pack a strong peppery flavor.
Tendergreen
A gentle, fast smooth-leaf type often grown as a spinach-mustard when you want milder eating.
How to propagate
Mustard greens are grown straight from seed, and you will find few crops come up faster or more dependably.
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
You could hardly ask for an easier seed to grow. Sow it shallow into cool, moist soil in early spring, then again in late summer for a fall crop, and it rewards you by coming up in 5 to 10 days with seedlings settled in around two weeks. Thin them to about 12 inches (30 cm) apart if you would like full-size plants, or leave them close for a friendly cut-and-come-again patch.
Myths
Mustard greens are poisonous to dogs and cats.
Take comfort in the fact that Brassica juncea is an everyday edible vegetable, and the ASPCA does not list it as toxic to cats or dogs. The goitrogen worry really belongs to livestock grazed heavily on the foliage, not to a pet that nibbles a leaf. For a household with pets, mustard greens are safe.
Mustard greens grow best in the heat of summer.
It is easy to assume otherwise, but this is a cool-season crop that shines in spring and fall. Summer heat only pushes it to bolt, and the leaves turn harsh and bitter once that happens. You will get far sweeter results by sowing it for the cool ends of the year instead.