Field mustard (Brassica rapa) is a plant that is widely cultivated and produces oilseed. Canola oil is made from the field mustard oilseed. Field mustard attracts white butterflies who gain nutrients from its flowers.
I. Appearance and CharacteristicsÂ
Brassica rapa is a plant species growing in various widely cultivated forms including the turnip (a root vegetable); Komatsuna, napa cabbage, bomdong, bok choy, and rapini.
Brassica rapa subsp. oleifera is an oilseed which has many common names, including rape, field mustard, bird’s rape, and keblock. The term rapeseed oil is a general term for oil from Brassica species. Food grade oil made from the seed of low-erucic Canadian-developed strains is also called canola oil, while non-food oil is called colza oil. Canola oil is sourced from three species of Brassica plants: Brassica rapa and Brassica napus are commonly grown in Canada, while Brassica juncea (brown mustard) is a minor crop for oil production.
The origin of B. rapa, both geographically and any surviving wild relatives, has been difficult to identify because it has been developed by humans into many types of vegetables, is now found in most parts of the world, and has returned to the wild many times as a feral plant. A study of genetic sequences from over 400 domesticated and feral B. rapa individuals, along with environmental modelling, has provided more information about the complex history. These indicate that the ancestral B. rapa probably originated 4000 to 6000 years ago in the Hindu Kush area of Central Asia, and had three sets of chromosomes. This provided the genetic potential for a diversity of form, flavour and growth requirements. Domestication has produced modern vegetables and oil-seed crops, all with two sets of chromosomes.
Oilseed subspecies (oleifera) of Brassica rapa may have been domesticated several times from the Mediterranean to India, starting as early as 2000 BC. Edible turnips were possibly first cultivated in northern Europe, and were an important food in ancient Rome. The turnip then spread east to China, and reached Japan by 700 AD. There are descriptions of B. rapa vegetables in Indian and Chinese documents from around 1000 BC.
In the 18th century, the turnip and the oilseed-producing variants were seen as being different species by Carl Linnaeus who named them B. rapa and B. campestris. Twentieth-century taxonomists found that the plants were cross fertile and thus belonged to the same species. Since the turnip had been named first by Linnaeus, the name Brassica rapa was adopted.
II. How to Grow and Care
Sunlight
Field mustard flourishes best in full sun, which ensures robust growth and optimal flowering. This plant benefits from the high intensity and long duration of direct sunlight, which bolsters its health and vitality. Although field mustard has a tolerance for partial sun, insufficient light may lead to leggy stems and reduced blooming. In outdoor settings, field mustard should be sited in areas that receive unobstructed sunlight for most of the day. For indoor growth, positioning near south-facing windows would provide the necessary light. Notably, field mustard can adjust its leaf orientation to maximize light absorption, optimizing photosynthesis under varying light conditions.
Temperature
Field mustard prefers to germinate and grow at relatively low temperatures. The biology of field mustard likes temperatures between approximately 20 to 25 ℃, but will also sprout at temperatures as low as 10 ℃. If temperatures are very low, planted seeds can be started on a heat mat and removed as soon as they have germinated. Brassica is one genus of vegetable with several well-known families which actually taste better after a frost; temperatures can drop below zero during the season.
Temperature is very important for the transition of field mustard from the vegetative to the reproductive phase. Whether growing these plants for leafy vegetables as a source of seeds or for breeding, temperature and timing should be carefully considered to achieve the desired result.
Plants of the genus Brassica are sensitive to moisture regardless of family. The large leaves of field mustard require considerable amounts of water, however equally the roots require ample drainage. Sandy soils tend to lose moisture too quickly for this genus, whilst clay holds too much. Growing of field mustard therefore calls for use of organic matter to ensure an adequate balance of moisture. The organic matter will also hold and supply trace elements, buffer pH and support beneficial organisms.
Watering
Originating from temperate regions, field mustard thrives in moist environments and requires consistent soil moisture to flourish. This species is moderately drought-tolerant but prefers a regular watering schedule to mimic its natural habitat’s conditions. Watering should occur twice a week to maintain optimal growth. As an outdoor plant often found in open fields, field mustard benefits significantly from rainwater, which provides the necessary hydration without accumulating excess salts that can be present in treated water sources.
Soil
Field mustard grows best in firm, fertile and naturally-draining soils. Areas to be planted should be dug over in the preceding fall, with stones removed and well-decomposed manure or compost worked in ready for the growing season. Growers can also tread on the soil area to ensure that air pockets have been removed and the surface made adequately firm. In terms of pH, all families of Brassica grow best in soils just below neutral at 6-7 except for collards and mustards which enjoy slightly more acidic soils and cabbages that will tolerate slightly alkaline soils up to a pH of 7.5.
Fertilizing
To foster robust growth in field mustard, a high-nitrogen fertilizer is advised; apply biweekly during peak growth periods. This regimen stimulates vigorous foliage and supports the plant’s rapid growth cycle. Limit fertilization to once per month in dormant seasons to prevent overfeeding. An inch of water following application aids in nutrient absorption. Employ a balanced approach during budding, blending high-nitrogen with phosphorous-potassium fertilizers, aiming for a flourishing yield. Always adhere to label rates, tailoring the dosage to the plant’s size and growth stage, ensuring a healthy, thriving field mustard.
Pruning
The large, thick low-lying leaves characteristic of many brassicas call for fairly regular maintenance and occasional pruning to ensure that leaves touching the ground do not start to rot. As well as removing possible sites for diseases to take hold, it helps to ensure that the plant’s energy is directed towards healthier growth. Any yellow, flat-looking leaves can simply be torn off or pruned with scissors. Large, healthy leaves covering other plants can also be removed but should be eaten.
Propagation
Field mustard propagates readily through sowing in the Spring. Ease of propagation is generally high. Look for germination and new growth as signs of successful propagation. Ensure proper soil moisture for optimal results.
Transplanting
The perfect time to transplant field mustard is during the refreshing early to mid-spring season, as it favors the plant’s growth. Choose a sunny location with well-drained soil to get the best results. Remember to give field mustard ample space to flourish and enjoy the process!
III. Uses and BenefitsÂ
- Ornamental uses
Vegetable gardeners prize field mustard for its edible leaves, buds, and stems. Despite some typical vegetable-growing challenges, it can also be used as border interest in other types of full sun to partial shade gardens. It combines well with other edible species like Peas, Beans, Carrots, Dill, and Spinach.
- Culinary uses
Many butterflies, including the small white, feed from and pollinate the B. rapa flowers.
The young leaves are considered an excellent leaf vegetable and can be eaten raw; older leaves are better cooked. The taproot and seeds can also be eaten raw, although the latter contains an oil which may cause irritation for some people.
IV. Harvesting and Storage
Harvesting of brassicas depends on family and variety. Summer cabbages cauliflower kohl and common broccoli can all be harvested from the end of summer whilst many others are good for picking in the fall or winter. Low growing brassicas such as cabbages should be harvested by cutting close to the ground level using a sharp knife. When harvesting cabbages the whole plant should be lifted to reduce the risk of club root. Broccoli should be harvested when flower shoots are well formed. Kale on the other hand can be harvested throughout the season on a frequent basis.
