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 its roots to Asia and now grows across the world's temperate gardens, equally at home in a Southern row or a Northern raised bed. Give it cool weather and it goes from seed to plate faster than almost anything else you can plant.
Speed is the whole appeal. A sowing can reach a first cutting in 30 to 50 days, and you can take the outer leaves young and let the center keep pushing fresh growth. Leave a plant to size up and it stands about 12 to 18 inches (30 to 45 cm) tall, but many gardeners crowd it close and harvest a steady patch of tender baby leaves instead.
The one thing mustard greens won't tolerate is heat. Warm weather and long days push the plant to send up a flower stalk, and once it bolts the leaves turn tough and harshly bitter. Sow it for the cool ends of the year, keep the soil evenly moist, and the flavor stays bright and clean.
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 quick harvest before summer heat turns the leaves bitter.
Light
Mustard greens grow best in full sun but take partial shade without complaint, which helps as the season warms. A little afternoon shade in late spring buys you time before the heat pushes the plants to bolt.
Water
Keep the soil evenly moist and water early so the leaves dry before nightfall, which holds fungal disease at bay. Don't let the plants dry out and rebound, since moisture stress turns the flavor unpleasantly sharp and spicy.
Soil
Plant in rich, well-drained ground worked with plenty of organic matter. A pH near 6.0 to 6.8 suits them best, though they handle soil up toward neutral, and good fertility drives the fast leaf growth you're after.
Temperature
This is a cool-season grower, happiest between 39°F and 75°F (4°C to 24°C). It shrugs off light frost, which can even sweeten the leaves, but warmth at the top of that range is what sets it bolting.
Humidity
Average humidity, somewhere around 40% to 70%, is all it asks. Airflow counts for more than any exact number, since crowded, damp leaves invite the fungal problems that watering early is meant to avoid.
Feeding
Work a nitrogen-rich balanced fertilizer into the bed at planting to fuel fast leaf growth. A light nitrogen side-dressing partway through keeps the leaves coming, but go steady, because 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 starts 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. Give full-size plants around 12 inches (30 cm) of room, or sow thicker and harvest the patch as baby leaves.
When to plant
Mustard greens are a cool-season crop with no love for heat. Sow the first round in early spring, about three weeks before your last frost, and sow again in late summer for a fall harvest. Cut the leaves young, and get the whole crop in before summer warmth pushes 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 trouble shows up on the leaves, and a quick daily look catches it early. Match what you see below to the cause, then act while the planting is still worth saving.
Seedlings wilting from tunneled, rotting roots
Seedlings that flop over for no clear reason are often falling to cabbage maggots, white larvae that tunnel through the roots below ground. Pull and destroy any plant that's already infested. Row covers laid down at sowing keep the egg-laying flies out, and skipping fresh manure removes what draws them in.
Fix:
- Remove and destroy infested plants
- Protect remaining plants with row covers
Tiny shot-hole pits peppering the leaves
Those pinprick holes are the work of flea beetles, small dark insects that hop away the moment you reach for them. Young seedlings take the worst of it. Cover the bed with floating row cover at sowing and keep the plants growing fast, since a vigorous plant shrugs off light feeding.
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
Big torn holes and dark droppings give away cabbageworms and cabbage loopers, green caterpillars that blend right into the foliage. Pick off the ones you find and spray Bt where they're heavy. The lasting fix is netting that keeps the parent moths from ever laying eggs.
Fix:
- Handpick caterpillars
- Apply Bacillus thuringiensis (Bt)
- Use row covers to exclude egg-laying moths
An early flower stalk and leaves gone tough and bitter
When a central stem shoots up and the flavor turns harsh, the plant is bolting, triggered by warm weather and longer days. There's no reversing it, so cut the leaves before they sour. Plant in the cool of spring or fall, shade the bed as the heat builds, and reach for bolt-resistant types.
Fix:
- Harvest promptly before flavor degrades; bolting cannot be reversed
Curled leaves with sticky residue and clustered insects
Crinkled tips and a sticky film point to aphids massing on the undersides. Blast them off with a hard spray of water, follow up with insecticidal soap if they regroup, and let lady beetles do the rest. Ease off the nitrogen too, since soft, lush growth is exactly what they crowd onto.
Fix:
- Dislodge with a strong spray of water
- Apply insecticidal soap
- Encourage lady beetles and other natural predators
Toxicity
Mustard greens are a food crop and safe to have around the house. No part of the plant poisons cats, dogs, or other pets, and the leaves themselves are good to eat. The only real note is for livestock grazed heavily on the foliage, where the goitrogens common to all brassicas can build up over time.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats None
Safe. The ASPCA does not list mustard greens among plants toxic to cats, so a nibble is nothing to worry about.
Dogs None
Safe. A dog that grazes a leaf comes to no harm, though a big helping of any leafy green can leave the stomach a little unsettled.
Horses Safe
Safe to graze in normal amounts, with no toxic compounds that put a horse at risk.
Rabbits Safe
Fine in moderation. Rabbits enjoy the leaves, so work them in gradually alongside hay and other greens rather than all at once.
Livestock Mild
Good forage and safe to eat, but heavy, day-after-day grazing on the brassica foliage can act as a goitrogen and press on the thyroid. Keep it one part of a varied diet.
Birds Safe
Safe. Backyard hens peck the leaves happily, and the greens make a healthy treat.
People Safe
Safe and good to eat. The peppery leaves are a kitchen staple, cooked or raw, with no part of the plant off limits.
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 few names turn up again and again. These are the ones worth knowing.
Florida Broadleaf
A fast Southern favorite that throws up large, smooth, broad green leaves you can start cutting young.
Southern Giant Curled
Its frilled, heavily curled bright green leaves take a frost better than the flat-leaved kinds do.
Giant Red
Grown for both color and bite, it carries purple red tinged leaves with a strong peppery flavor.
Tendergreen
A mild, quick smooth-leaf type often grown as a spinach-mustard for milder eating.
How to propagate
Mustard greens are grown straight from seed, and few crops come up faster or more reliably.
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
Mustard greens are about as easy as seed gets. Sow shallow in cool, moist soil in early spring, then again in late summer for a fall crop, and the seeds come up in 5 to 10 days with seedlings settled in about two weeks. Thin them to roughly 12 inches (30 cm) apart if you want full-size plants rather than a tight cut-and-come-again patch.
Myths
Mustard greens are poisonous to dogs and cats.
Brassica juncea is an everyday edible vegetable, and the ASPCA does not list it as toxic to cats or dogs. The goitrogen worry 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.
This is a cool-season crop that does its best work in spring and fall. Summer heat pushes it to bolt, and the leaves turn harsh and bitter once it does. Sow it for the cool ends of the year instead.