Grow cabbage

Humans and cabbages have shared a common history for a long time. Kale is a very old form of cabbage, but here I will be focusing on some of its great grandchildren, the modern, headed cabbages in the Brassica oleracea Capitata Group.

It’s easy to think it’s we humans who have gained the most from the human-cabbage relationship. But if you think of the time we’ve devoted to cabbages, with generations of breeding and selecting the strongest, biggest and best, they’ve done all right too. They are biennial plants, but we grow them as annuals, harvesting before they mature and set seed.

Capitata means ‘headed’, and there are three main types in the group. The most widely grown are the white or green types, which can be bluish green, grassy green or yellowy green. This is split further into three subgroups, determined by the shape of their head – conical, drumhead and ball head. The other less commonly grown types are Savoy, with their looser heads and distinctive crinkled leaves, and rubra or red, which have tight heads and deep purple glossy leaves, and are just as beautiful in a flower border as a vegie patch.

Growing and harvesting cabbage

The best cabbage heads are grown in cool and moist conditions. In cool areas, they can be grown throughout the year, while in hotter areas, they are best grown in autumn and winter. 

I prefer to raise plants from seed in trays rather than sow directly in the ground. Seedlings can be planted out after about a month, then you’ll be able to watch them expand. They are available to buy as seedlings, but select your cabbage plants carefully, and look for signs of stress – pale leaves, leggy growth and insect damage. 

Select an open, sunny position where their giant leaves can make the most of the sun’s rays. Sweeten acidic soils with garden lime or dolomite to help prevent calcium deficiency and club root, a common disease problem. Give them a rich, well-drained soil, and when I say rich I mean triple-choc-mud-cake rich, with a healthy serving of compost and well-rotted manure, plus a good sprinkling of a complete organic fertiliser. They can grow to the size of a small moon, so need a fully stocked pantry and deep drinks when it’s dry.

Harvest when the heads are firm and have developed to the desired size. Pull up the whole plant then trim off the unwanted outer leaves, so it’s ready for the kitchen.

Pests and problems

With their hefty nature and voracious appetite, cabbages are prone to nutrient deficiencies. When soil is lacking in calcium, the young leaves deform and the edges may look slightly scorched – the older leaves tend to collapse completely. If you have ever had hollow stems in your cabbages, then you need to add boron to your soil. Many Australian soils are boron deficient, particularly where I live in Tasmania, so I have to keep an eye out for this. 

Iron and magnesium deficiency look fairly similar, with both causing a yellowing of the leaves while the veins stay green, but a lack of magnesium affects the older leaves first – while iron deficiency shows up everywhere on the plant. If your soil is low in phosphorus, the older cabbage leaves start to look purple, which can make diagnosis a little challenging if you are growing a purple variety. With follow-up applications of organic fertiliser every six weeks or so, you should be able to provide the phosphorus cabbages need.

Many creatures will see your cabbage crop as an all-you-can-eat buffet. Grubs and caterpillars are common uninvited dinner guests, but can be stopped by covering crops with fine exclusion netting or spraying leaves with a commercial organic deterrent. Slugs and snails can decimate seedlings and ruin the quality of mature cabbages, so be prepared to maintain appropriate baits, particularly in moist conditions. Aphids seriously reduce plant vigour so you’ll need to hose them off if they are present, or apply a soap spray. 

My general advice is to ensure your plants have everything they need – adequate food, water, a good position and soil that drains well – because a healthy plant is better able to look after itself. I grow most of my cabbages over winter, as many of these pests are less active during that period. 

Diseases, such as powdery mildew, downy mildew, rust and leaf spot, may be an issue in wet weather. If you see any foliage that looks diseased, remove it, carefully wrap it up and dispose of it in the rubbish bin to help prevent it spreading.

Header image credit: iStock

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