https://www.almanac.com/plant/cabbage by Catherine Boeckmann
Cabbage is a cool-season vegetable suited to both spring and fall.
We now know that this hardy vegetable is antioxidant- and nutrient-rich, and a great addition to any garden!
That said, note that cabbage can be challenging to grow for the beginner gardener if you don’t have the right conditions; it only likes cool temperatures and it can be a magnet for some types of garden pests. Rotating the cabbage crop every few years avoids buildup of soilborne diseases.
When to Plant Cabbage
If starting seeds indoors, sow half a cm deep 6 to 8 weeks before the last spring frost. Consult your Planting Calendar for suggested dates.
For a fall harvest, direct sow seeds outdoors (or plant transplants) in mid- to late summer. If your area is particularly hot and dry, hold off on planting until late summer. Make sure that the young plants don’t dry out in the summer sun’s heat!
Choosing and Preparing a Planting Site
Cabbage is a heavy feeder; it quickly depletes the soil of required nutrients. Prepare the soil in advance by mixing in aged manure and/or compost. Soil should be well-draining: roots that stand in water cause heads to split or rot.
How to Plant Cabbage
Before planting the seedlings outdoors, harden off the plants over the course of a week. Transplant small plants outdoors on a cloudy afternoon 2 to 3 weeks before the last spring frost date. Plant seedlings 30-50cm apart in rows, depending on the size of head desired. The closer you plant, the smaller the cabbage heads.
How to Grow Cabbages
When seedlings reach about 13cm tall, thin to leave the desired space between them. If you wish, transplant the thinned seedlings elsewhere. Mulch thickly around the area to retain moisture and regulate soil temperature. Water as needed.
The optimum soil temperature for growth is around 18°C. Young plants exposed to temperatures below 7°C for a period of time may bolt or form loose heads. Cover plants if cold weather is expected. Fertilize 2 weeks after transplanting with a balanced organic fertilizer or more compost. Three weeks later, add a nitrogen-rich organic fertilizer; cabbage needs nitrogen in the early stages. Practice crop rotation with cabbages to avoid a buildup of soil-borne diseases.
Misshapen/yellow leaves; distorted flowers/fruit; sticky “honeydew” (excrement); sooty, black mold
Grow companion plants; knock off with water spray; apply insecticidal soap; put banana or orange peels around plants; wipe leaves with a 1 to 2 percent solution of dish soap (no additives) and water every 2 to 3 days for 2 weeks; add native plants to invite beneficial insects
Yellow, V-shape areas on leaf edges that brown and progress toward leaf center; leaves eventually collapse; stem cross sections reveal blackened veins
Destroy infected plants; choose resistant varieties; provide good drainage; remove plant debris; rotate crops
Large, ragged holes in leaves from larval feeding; defoliation; stunted or bored heads; excrement
Handpick; add native plants to invite beneficial insects; spray larvae with insecticidal soap or Bt; use row covers; remove plant debris
Wilted/stunted plants; off-color leaves; larvae feeding on roots
Use collars around seedling stems; monitor adults with yellow sticky traps; use row covers; destroy crop residue; till soil in fall; rotate crops
Leaves have large, ragged holes or are skeletonized; heads bored; dark green excrement; yellowish eggs laid singly on leaf undersides
Handpick; use row covers; add native plants to invite beneficial insects; grow companion plants (especially thyme); spray Bacillus thuringiensis (Bt)
Wilted/stunted plants; yellow leaves; roots appear swollen/distorted
Destroy infected plants; solarize soil; maintain soil pH of around 7.2; disinfect tools; rotate crops
Yellow, angular spots on upper leaf surfaces that turn brown; white/purple/gray cottony growth on leaf undersides only; distorted leaves or corn tassels; defoliation
Remove plant debris; choose resistant varieties; ensure good air circulation; avoid overhead watering
Numerous tiny holes in leaves
Use row covers; mulch heavily; add native plants to invite beneficial insects
Irregular holes in leaves/flowers; gouged fruit; slimy secretion on plants/soil; seedlings “disappear”
Handpick; avoid thick bark mulch; use copper plant collars; avoid overhead watering; lay boards on soil in evening, and in morning dispose of “hiding” pests in hot, soapy water; drown in deep container filled with 1cm of beer, or sugar water and yeast, and sunk so that top edge is slightly above ground; apply 3cm-wide strip of food-grade diatomaceous earth as barrier
Yellow/white blotches on leaves; scarred, dimpled, or distorted fruit/pods; shriveled seeds; eggs, often keg-shape, in clusters on leaf undersides
Destroy crop residue; handpick (bugs emit odor, wear gloves); destroy eggs; spray nymphs with insecticidal soap; use row covers; weed; till soil in fall
Leaves, especially in folds near base, have white patches or silver streaks; brown leaf tips; blistering/bronzing on cabbage leaves; brown streaks on cauliflower curds; bulbs/ heads distorted or stunted; curling or scarring
Remove plant debris; choose resistant varieties; add native plants to invite beneficial insects; use row covers; use straw mulch; monitor adults with yellow or white sticky traps; use sprinklers or other overhead watering
Pale gray, “water-soaked” areas on stems, leaves, and other plant parts that enlarge and develop white, cottony growth, later with black particles; bleached areas; crowns/ fruit rot; plants wilt/collapse
Destroy infected plants; ensure good air circulation; water in morning; weed; destroy crop residue; rotating crops on 5-year or longer cycle may help
Harvest when heads reach desired size and are firm. Mature heads left on the stem may split. Days to maturity is around 70 days for most green cabbage varieties and most produce .5 to 1.5 kg heads.
To harvest, cut each cabbage head at its base with a sharp knife. Remove any yellow leaves (retain loose green leaves; they provide protection in storage) and immediately bring the head indoors or place it in shade. Alternatively, pull up the plant (roots and all) and hang it in a moist cellar that reaches near-freezing temperatures.
To get two crops, cut the cabbage head out of the plant, leaving the outer leaves and root in the garden. The plant will send up new heads; pinch off those until only four or so smaller heads remain. Harvest when tennis ball-size (perfect for salads!).
After harvesting, remove the entire stem and root system from the soil to prevent disease. Only compost healthy plants; destroy any with maggot infestation.
How to Store Cabbages
In proper root cellar conditions, cabbage will keep for up to 3 months.
Follow this old-time technique to get the most out of your cabbage crop:
In the fall, harvest the entire cabbage plant—stems, head, and roots—enjoying the head as usual and storing the roots in a root cellar through winter. As soon as the ground has thawed in spring, plant the roots outdoors. Soon, fresh sprouts will form, which can be eaten alone or added to soups, salads, or a dish of your choice.These replanted cabbages won’t produce full heads, but they should go to seed by the end of summer, providing next year’s round of cabbage seeds!