Cabbage (Brassica oleracea var. capitata)

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Common name

Scientific name

Life cycle

Sexual system

Primary pollination method

Inbreeding/
outbreeding

Min. isolation distance

Min. population size for variety maintenance

Min. population size for genetic maintenance

Number of seeds per gram

Average storage life

Comments

Cabbage (English),
Chou cabus (French), Repollo (Spanish)
Brassica oleracea var. capitata Biennial Monoecious Insects Strongly outbreeding 250-800 m 20-50 80+ 190-300 4 years Will cross with all B. oleracea crops ; Must undergo vernalization in order to flower

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Cabbage is one of the most consumed brassica in the world. Most likely domesticated in Europe before 1 000 BC, it has today become a prominent part of European as well as Asian cuisines, whose heads are prepared in many different ways. Thanks to centuries of climatic and human selection, cabbages have evolved into several different head shapes and colors, with flavor varying depending on the variety.

Cabbage is a good source of vitamin K, vitamin C and dietary fiber.

Growing recommendations

Cabbages are biennial, cool weather plants (commonly grown as annuals) that grow best in late-summer to fall in most climates but can also be planted in spring. They prefer full sun, but can still perform well in partially shaded areas. The plant is suitable for light (sandy), medium (loamy) and heavy (clay) soils, provided it is moist but well-drained. While cabbages are usually grown in soils with a neutral pH, they can be planted in very acid or alkaline ones. The plant can also tolerate maritime exposure.

Cabbages can be planted early in the season. They can be started indoors about six to ten weeks before the last expected frost date, then transplanted in the garden a couple of weeks before this date. The plant can be direct seeded throughout the summer, provided the temperature isn’t too high. Seeds will germinate at a temperature of about 20° C within 5-10 days. Cabbages meant for seed production should be thinned out to 60 cm.

The plants are known to be prone to several nutrient deficiencies, multiple pests, as well as bacterial and fungal diseases. Based on your environment, adequate techniques and control solutions will have to be used whenever deemed appropriate.

Pollination, crossing, and isolation

Cabbages are in flower from May to August, with the seeds ripening from July to September. The species bears hermaphrodite flowers, having both male and female organs, that are pollinated by bees. Most cabbages are self-incompatible and must indeed be pollinated by insects in order to produce viable seeds. As strong outbreeders, they will need to be isolated accordingly with appropriate techniques in the event several varieties are grown simultaneously in the garden or in the vicinity. Cabbages will indeed easily cross with each other, as well as with all other varieties within the Brassica oleracea species. If spatial isolation is not possible, advanced seed savers may want to use alternate day caging with or without the introduction of pollinators.

General seed saving guidelines (harvesting and processing)

As a biennial plant, cabbages will require two seasons to produce seeds and must undergo vernalization in order to induce flowering. In mild climates, cabbages can be left outside in the garden to overwinter. In cold winter areas, selected plants will need to be carefully dug out in the fall and stored in a humid place (80-90%) at about 0-4° C for 2-4 months. The firmest heads are chosen, the loose leaves trimmed off, the entire plant dug up, and the roots clipped to 30 cm while leaving some lateral roots. The heads are then stored and covered with damp sawdust. Some losses are to be expected. They are replanted in the following spring. It may help to cut a shallow “X” (2 to 4 cm deep) on the top of the cabbage head to promote the seed stalk to emerge.

As they mature, the seedpods (called siliques) will start to dry and turn brown. However, if the plants are allowed to fully dry in the field, one run the risk of them shattering, which might attract birds and result in important losses. Several hand harvests can be conducted over several weeks as the seeds dry or the whole mature stalks can be cut and dry further on tarps in a protected area for a few days (which is best). The stalks can then be threshed by placing them inside a bag and trampling over it, or the seedpods stripped and rubbed gently to crush them and release the seeds. The threshed pods can be cleaned by winnowing and/or with the help of screens. If a source of wind is used to remove the chaff, ensure that the processing area is covered by a tarp, which will help recover any seed that has been accidentally blown out of the winnowing container. Do not forget to clean it after each new variety to avoid any accidental mixing.

Cabbage seeds will remain viable for an average of four years when stored under optimum conditions.