Brassica juncea

Introduction: This species is believed to be a hybrid of B. rapa and B. nigra. It has been most highly refined in China, where it is a very important cool season vegetable.

This is the green leaf mustard, not the condiment mustard, which is made from the ground seeds of B. nigra and B. alba. However this species can be used for making mustard too.

Ease of growing: If given the right conditions mustards are one of the most easily grown and fast maturing crops you can grow. They produce heavily in a small area and require little effort to grow.

Crop value: I have to admit that I overlooked mustard for a long time. I guess I was put off for a long time because they can get very pungent in hot weather. Only relatively recently have I come to appreciate its’ many virtues (speed of growth, nutritional value and (often) mild flavor.

The mustards definitely deserve to be more widely cultivated in the west, especially in small gardens where space is limited. We in the west have a lot to learn from China about growing food in small spaces.

The one place you commonly find mustard leaves is in commercially grown salad mixes.

Nutritional content: These are some of the most nutritious leafy greens, rich in vitamins A and C, as well as calcium, iron and potassium. Like other Brassicas they also contain a variety of cancer preventing phytochemicals.

Mustard seeds are very rich in the glucosinolate phytonutrients (these are powerful antioxidants), as well as selenium, magnesium and omega 3 fatty acids. All of these are responsible for making the condiment mustard (see recipe below) a surprisingly nutritious food and medicine. When you eat mustard for its flavor you can be smugly satisfied that you are also eating a very beneficial food supplement (though even this can’t turn a hot dog into a health food).

About Mustards  
Seed facts
Germination temp: 45 – 95°F
Germination time: 2 – 7 day
Viability: 3 – 8 years
Germination percentage: 75%+
Seed viability: 4 years
Weeks to grow transplant: 3 – 4  

Planning facts
Hardiness: Hardy
Growing temp: 45 (55 – 65) 75°F
Plants per person: 5
Plants per sq ft: 4  

Start: 6 wks before last frost
Plant out 2 wks before last frost
Direct sow: 2 wks before last frost
Fall crop: Sow 6 – 8 wks before first frost
Succession sow: Every 4 weeks  

Harvest facts
Days to harvest:
20 – 40 days (summer)
60 days (winter)
Harvest period: 8 – 10 weeks
Yield per plant: 1 lb
Yield per sq ft: 2 – 4 lb  


pH 5.5 – 6.8

Mustards aren’t particularly fussy about soils, but will be most productive on rich moisture retentive ones.

Soil preparation: If the soil is poor, dig in 2˝ of compost or aged manure, as well as wood ashes or greensand (for potassium), colloidal phosphate (for phosphorus) and kelp (for trace elements). You could also simply use a fertilizer mix to supply all of these.


Where: The ideal spot for mustards depends on the weather. If it’s cool they should be planted on an open sunny site. If it’s warm they will benefit from some shade during the hottest part of the day.

Mustards are in and out of the ground quickly, so are commonly grown as an intercrop between slower growing plants.

Crop rotation: They should not be planted where another Brassica has grown in the past 3 years.

When: These fast growing plants will grow well in both warm and cool weather, but taste better when it’s cool.

Mustards can be planted at any time as a cut and come again crop. Just plant a small section of bed every two weeks (space the plants ½˝ apart), keep cool and well watered and see how it goes.

Spring: Mustards can be started indoors 6 weeks before the last frost and planted out 2 – 3 weeks later. Start direct sowing about 2 weeks before the last frost date, so they have time to mature before it gets hot. They are somewhat prone to bolting when planted at this time however and generally do better as a fall crop.

Summer: In cool climates, it is possible to succession sow the mustards all summer.

Fall: Mustards generally work best as a fall crop and (like many Brassicas) cold weather actually improves their flavor. Direct sow a fall crop at least 8 weeks before the first fall frost is expected.

Winter: Mustard thrives in cool weather and can even take quite a bit of frost (some varieties will take temperatures as low as 18°F). In milder areas it makes a great winter crop. It will also work in colder areas if it is grown under cloches or in poly tunnels.


Mustards can be direct sown or transplanted.


Starting inside: Mustard doesn’t mind transplanting, so is easily started indoors in flats or soil blocks. However you gain little time by doing this because it germinates well at low temperatures and grows quickly outside. I suppose it may be worthwhile in early spring to get a head start, or if you want to save bed space or avoid pests.

Direct sowing: Mustard is usually direct sown, by broadcasting and then covering with ¼ – ½˝ of soil (or a mix of half soil and half compost). It doesn’t mind being crowded so plant thickly and slowly thin to the proper spacing (eat the thinnings).

It can also be sown in rows, just make shallow ½˝ deep furrows and space the seeds ½˝ apart.


Bed spacing: Space the plants 6 – 12˝ apart each way. Exact spacing depends upon the variety.

Row spacing: Space the plants 1 – 4˝ apart, in rows 12 – 24˝ apart.


For best quality you want your mustard plants to grow as fast as possible, which means giving them everything they need.

Water: If the soil is too dry the plants will develop a bitter and pungent flavor. If you want tasty, mild flavored mustard greens you must keep it moist at all times

Fertilization: If the soil is less than ideal, you may want to feed your plants with a foliar fertilizer such as compost tea. Do this after thinning them to their final spacing and again as necessary.

Mulch: This is primarily of value to keep down weed growth and keep the soil moist. It can also help to keep the soil cool, which can delay bolting.

Pests: Mustards suffer from the same pests as the other Brassicas, but especially flea beetles and cabbage root fly (see Cabbage for more on these).

Slugs and snails can be a serious problem early spring when there is not much else for them to eat. They can wipe out a new planting almost overnight. The best approach is to go out with a flashlight after dark and hand pick them.


Harvest mustards by cutting the whole plants, leaving several inches of stem behind. The remaining stem will then resprout and grow another crop (you can sometimes cut them several times).

Alternatively you can harvest single leaves, as soon as they get large enough (about 3˝ high).

If the plants bolt before you get a chance to harvest them, all is not lost.

If it is big enough, the immature flower stalk can be eaten like broccoli raab. The flowers and green seedpods can be added to salads. Of course you can also collect the seed for various purposes.

Seed saving: It’s easy to save seed from these annuals. Just treat them like kale and gather the seed at the appropriate time. Be careful not to let it self-seed too much, as it can become a weed if it gets established (though perhaps not an unwelcome one).

Mustard can produce far more seed than you need for propagation. You can use the surplus for growing cut and come again salad greens and micro-greens, or for sprouting like alfalfa (they make excellent, slightly spicy sprouts). They can even be used for making the super-nutritious condiment mustard (see below).

Unusual growing ideas

Cut and come again salad greens: Pungent mustard leaves are a basic ingredient of salad mixes. The red types are particularly prized, as they add color as well as flavor. (See Salad mix).

Micro-greens: This is just a smaller version of the above. You plant the seeds ¼˝ apart and harvest them when the first true leaves appear, which of often within a few days. See Micro-greens

Winter crop: Some mustard varieties are very hardy (especially the oriental types) and make excellent winter crops for mild climates. They can also be used in colder climates if protected by cloches, or grown in a cold frame or greenhouse. If it gets very cold they may stop growing, but they won’t be damaged and will resume growing when the temperature rises sufficiently.

Ornamentals: Some mustards have unusual foliage and are quite ornamental. These may be planted in ornamental borders to fill any unsightly gaps. Start the seedlings inside, or in a nursery bed and transplant them as vacant spaces appear.

Green manures: These fast growing plants are often grown as green manures, as they produce a large amount of biomass in a short time. An advantage is that you can also eat them. A disadvantage is that they are members of the Brassica family and so subject to all of their afflictions.


There is a lot of variation in this crop.

Western mustards

These are some of the most commonly used varieties.

Southern Giant – Large, hardy plant, very productive (55 days)

Florida Broadleaf – Large mild tasting leaves (45 days)

Savannah F1 – Early and slow bolting (35 days)

Tendergreen – This is commonly thought of as a mustard, but is actually a kind of turnip (see Turnip).

Eastern mustards

(Gai Choy)

The mustards are much more important vegetables in Asia than they are in the west. They can be divided into a number of different types.

Broad leaved Mustard

(Brassica juncea var rugosa)

Osaka Purple

Red Giant

Ruby Streaks

These are all good for salad mixes as they add color as well as flavor.

Leaf mustard

(Brassica juncea var foliosa)

San-Ho Giant – Very large plant for fall growing.

Curled Mustard 

(Brassica juncea var crispifolia)

Green Wave: This curly mustard is very hardy, fast growing and resistant to pests.

Green-in-the-Snow, Snow Cabbage, Shi-Li-Hon

(Brassica juncea var multiceps). This very hardy (down to 20°F) type is grown in cold weather (as the name suggests). It doesn’t work well in warm weather though.

Kitchen use

The tender leaves can be used raw in salads, cooked as a potherb, or in soups and stir-fries. If they are very pungent try cooking with blander greens, or change the cooking water half way through.

Prepared Mustard  

1 tbsp coriander seeds
6 tbsp mustard seeds
1 tbsp black peppercorns
¼ cup chopped onion
½ tsp dried thyme
2 cup water
2 tsp honey
¼ cup red wine vinegar
½ tsp ground turmeric  

Toast the coriander seeds in a skillet, then crush them with the mustard seeds, and peppercorns. Mix with the thyme, onion, turmeric and leave
for three hours. Add water and vinegar and honey and simmer 10
minutes, being careful it doesn’t burn. It will get thick.  

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