Field Mustard – Brassica Rapa: Edible & Medicinal Uses of the Mother Cruciferous of Wild Plants

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You’re unlikely to find the popular white or black mustards here in the wild. The only brassica on iNat for Haliburton, Ontario is field mustard (brassica rapa). It’s more of a wild cabbage or wild turnip. It’s the mother of many vegetables you’ll find in the grocery store, but not a “true mustard” renown for spicy condiments and hot plasters.

Brassica rapa has been cultivated and turned into the likes of turnips, napa cabbage, rapina, bok choy and other widely eaten vegetables. One type of rapa (var. sylvestris Lam.) makes the popular oilseed canola. The plant recorded in Haliburton Flora was along a gravel bank, probably having taken a ride on an ATV through someone’s vegetable garden to said spot. I might have ignored this plant, but it’s interesting to ponder how we’ve turned many wild plants into garden vegetables. In many cases we’ve vastly improved the taste, texture, etc.

When it comes to mustards in herbal medicine, white and black from the species brassica juncea get the most glory. None of the juncea were noted in Haliburton Flora. The mustard plasters you may have heard of are from this group. And that wall of condiments at the grocery store. Anything requiring “true mustard seeds” will only be skimmed over here.

Field Mustard -  Brassica Rapa
Field Mustard – Brassica Rapa

Edible Uses of Field Mustard

Field Mustard -  Brassica Rapa
Field Mustard – Brassica Rapa

All wild and cultivated mustards are edible. Young greens can be eaten raw or boiled about 30 minutes. Older leaves can use a couple changes of water during boiling to reduce their bitterness. The leaves are like a coarse spinach. And they can be blanched and frozen.

Its tender young aerial parts are all edible. The young buds can be eaten like broccoli, ideally steamed. And yes, broccoli came from a brassica species too! This genus provides us with many healthy cruciferous vegetables; Euell Gibbons called this genus “nature’s finest health food.” Older aerial parts including the flowers can be eaten as well, but their bitterness may be off-putting.

The young roots can be eaten raw or cooked and have a radish-like bite to them. But moreso in juncea spp.

Similarly, “true mustard” seeds of the juncea spp. make the best mustard, but you could try making a mustard with field mustard/wild cabbage/turnip too. You can use any edible mustard seeds whole in curries, pickling blends, vinegars, etc. Harvest seeds when the pods have dried up. They can be dried and stored at least a year. Alternatively and perhaps no surprise, the young seedpods are edible too. Did we leave any part uneaten? No wonder rapa was bred into so many vegetables.

Rich in Vitamins A, B, C and trace minerals.

Medicinal Uses of Field Mustard

Field Mustard is primarily said to support these body systems:

  • X

Medicinal tags include Counterirritant and Diuretic. See Medicinal tag key for more information.

Common usage includes its juncea relations in mustard plasters and other remedies. Mustard plasters were once purchasable at stores, but they are tricky to work with because they will burn skin quickly, even causing blisters if misused.

The “field mustard” we’re featuring today isn’t traditionally used for plasters. However, the seeds of most brassicas redden skin and can cause digestive irritation if consumed in great quantity. Like Euell Gibbons indicated, brassicas simplest medicinal use is that it’s a very nutritious genus, which goes a long way to prevent disease. Eat you broccoli.. and your cabbage, cauliflower, collard greens, brussels sprouts, kale, kohlrabi, turnip, etc.

Field Mustard -  Brassica Rapa
Field Mustard – Brassica Rapa

Alternative Uses of Wild Turnip

Root peelings can be chopped and brewed into a tea, with flakes of soap added, to treat plants against pests like aphids or red spider mites. But I’d recommend attracting native lady bugs and other beneficial aphid-eaters instead.

Growing Brassica Rapa

Mustards are all nonnative to our region, and for the vegetable garden. But they don’t seem to escape the plot very often, and certainly not to the harmful degree parsnip has. You can easily sow them for spring greens by planting seeds in the autumn to overwinter.


And the Usual Cautions:

1) Most medicinal herbs, if edible, are meant to be eaten in moderation, even sparingly. Some require extra preparation. Tannins are toxic if consumed in excess.

2) People can be allergic or sensitive to nearly any plant; try new herbs one at a time at your own risk. For instance, saponins commonly cause stomach upset.

3) For medicinal use, I must recommend receiving a diagnosis and working with a reputed health care provider. I generally do not post specific treatments and dosages because I think that is best between you and your health care provider, and ideally monitored.

4) Anyone pregnant, nursing, or taking prescription drugs should talk to a health care professional before adding new food items to their diet.

5) Many plants have look-a-likes, and sometimes they are poisonous.

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Northeast Foraging: 120 Wild and Flavorful Edibles from Beach Plums to Wineberries (Regional Foraging Series)

Edible and Medicinal Plants of Canada

A Modern Herbal (Volume 2, I-Z and Indexes)

Stalking The Wild Asparagus (Field Guide Edition).

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