How to Sow
- Broccoli Raab is a cool season crop sown in average soil in early spring as soon as the soil is workable.
- Sow in rows 8-12 inches apart, cover with ¼ inch of fine soil.
- Keep evenly moist.
- Seedlings emerge in 10-21 days.
- Thin to stand about 4-6 inches apart when seedlings are 1-2 inches high.
How to Grow
- Keep weeds under control during the growing season. Weeds compete with plants for water, space and nutrients, so control them by either cultivating often or use a mulch to prevent their seeds from germinating. Avoid disturbing the soil around the plants when weeding.
- Keep plants well watered during dry periods to promote rapid, uninterrupted growth.
- Monitor for pests and diseases. Check with your local Cooperative Extension Service for pest controls recommended for your area.
Harvest and Preserving Tips
Plants produce an abundance of small leaves and many side-shoots no larger than a quarter.
Pick shoots and leaves in about 35 days.
Harvest whole plants when sprouts are 1-2 inches across just as they begin to flower.
Keep picking to extend harvest.
Common Disease Problems
Alternaria Leaf Spot: Small, round reddish brown spots with white to gray centers for on the upper surface of the leaves. The lesions may encircle the stems and cause wilt. This disease is worse in warm, wet or very humid weather. Burpee Recommends: Avoid getting water on the foliage. Remove infected plant parts and do not work around wet plants. Provide plenty of air circulation. Contact your Cooperative Extension Service for fungicide recommendations.
Clubroot: This causes plants to wilt in patches during the day, stunts their growth, and causes swollen or disfigured roots. Burpee Recommends: Rotate crops with plants in a different family. Avoid overhead watering. Provide adequate air circulation, do not overcrowd plants. Improve drainage by reducing soil compaction. Do not work around plants when they are wet. Control weeds where the disease can overwinter.
Damping Off: This is one of the most common problems when starting plants from seed. The seedling emerges and appears healthy; then it suddenly wilts and dies for no obvious reason. Damping off is caused by a fungus that is active when there is abundant moisture and soils and air temperatures are above 68 degrees F. Typically, this indicates that the soil is too wet or contains high amounts of nitrogen fertilizer. Burpee Recommends: Keep seedlings moist but do not overwater; avoid over-fertilizing your seedlings; thin out seedlings to avoid overcrowding; make sure the plants are getting good air circulation; if you plant in containers, thoroughly wash them in soapy water & rinse in a ten per cent bleach solution after use.
Downy Mildew: This fungus causes whitish gray patches on the undersides and eventually both sides of the leaves. Burpee Recommends: Rotate crops with plants in a different family. Avoid overhead watering. Provide adequate air circulation, do not overcrowd plants. Do not work around plants when they are wet.
Powdery Mildew: This fungus disease occurs on the top of the leaves in humid weather conditions. The leaves appear to have a whitish or greyish surface and may curl. Burpee Recommends: Avoid powdery mildew by providing good air circulation for the plants by good spacing and pruning. Contact your Cooperative Extension Service for fungicide recommendations.
Common Pest and Cultural Problems
Aphids: Greenish, red, black or peach colored sucking insects can spread disease as they feed on the undersides of leaves. They leave a sticky residue on foliage that attracts ants. Burpee Recommends: Introduce or attract natural predators into your garden such as lady beetles and wasps who feed on aphids. You can also wash them off with a strong spray, or use an insecticidal soap.
Cabbage Looper: These worms are green with a white stripe on either side, about 1-1.5 inches long. They tunnel through the heads. Burpee Recommends: Hand pick. Floating row covers can help prevent their laying eggs on the plants.
Flea Beetles: These small hopping beetles feed on plant foliage and can spread disease. Burpee Recommends: Rotate crops with plants in a different plant family. Use floating row covers to prevent damage to young foliage.
Leafminers: These insects bore just under the leaf surface causing irregular serpentine lines. The larvae are yellow cylindrical maggots and the adults are small black and yellow flies. They do not usually kill plants, but disfigure the foliage. Burpee Recommends: Remove affected foliage.
Slugs: These pests leave large holes in the foliage or eat leaves entirely. They leave a slime trail, feed at night and are mostly a problem in damp weather. Burpee Recommends: Hand pick, at night if possible. You can try attracting the slugs to traps either using cornmeal or beer. For a beer trap, dig a hole in the ground and place a large cup or bowl into the hole; use something that has steep sides so that the slugs can’t crawl back out when they’re finished. Fill the bowl about ¾ of the way full with beer, and let it sit overnight. In the morning, the bowl should be full of drowned slugs that can be dumped out for the birds to eat. For a cornmeal trap, put a tablespoon or two of cornmeal in a jar and put it on its side near the plants. Slugs are attracted to the scent but they cannot digest it and it will kill them. You can also try placing a barrier around your plants of diatomaceous earth or even coffee grounds. They cannot crawl over these.
Broccoli Raab FAQs
My plants are flowering, why is this? Broccoli raab is a cool season crop and can produce a flower stalk when temperatures are high. At this stage the plants have completed their season and you should pull them out.
When should I sow broccoli raab in fall? If temperatures are over 85 degrees F in your area in August, start plants indoors the beginning of August. If temperatures are consistently under 85 degrees in August, direct sow at the end of July.
Why does my broccoli raab taste bitter? It is the nature of broccoli raab to taste bitter; it is not the same as broccoli. The leaves and flower buds are used in Chinese and Italian cooking and chosen for the bite they impart. The bitterness may be moderated to some extent by blanching prior to cooking. To do this, drop into boiling water for 2-4 minutes, then plunge into cold water to stop the cooking, drain and use.
Can I grow broccoli raab in containers? Yes, but only in a large container 24 inches deep and wide. Be sure to use a commercial container mix rather than garden soil.
Can I use the leaves of my broccoli raab in cooking? Yes, broccoli raab is grown for the leaves as well as the small flower buds.