Broccoli belongs to the Brassica family of vegetable, otherwise known as the cabbage family or the cole family. These relatives include cauliflower, Brussels sprouts, and kale. You can enjoy broccoli over a long season, not just by harvesting the center head, but all the smaller secondary heads that sprout up after the main one is cut.
The pH of the soil should ideally range from 6.2 to 7.0. This range will discourage clubroot disease. Amend your soil with two inches of compost worked into the dirt. Broccoli likes very fertile, well-drained, loamy soils. If your soil is very sandy or composed of a lot of clay, add organic matter to it.
When to Plant
Start your seeds indoors about 6 weeks before you plan to transplant them outside. Cole crops are cool weather vegetables and grow best when daytime temperatures are between 65 and 80 degrees F. In the North set out your transplants about two weeks before the last frost date and plant a fall crop about 10 to 12 weeks before the first fall frost date. In the South, start seeds January through March. Start seeds for your fall crop in late July through September.
How to Plant
While broccoli can be seeded into the garden, it’s better to use transplants. It’s easy to start your seedlings indoors and they grow fairly fast. Plant your seedlings 18 inches apart with 2 feet between the rows. Plant them firmly to insure they crop well. Water in with a liquid organic fertilizer such as Protogrow® to encourage vigorous growth.
Plants should receive 1 to 1 1/2 inches of water per week. Water regularly if no rainfall is occurring. Help keep soil moist by the application of mulch, either straw, compost, ground leaves, or finely ground bark.
While broccoli needs full sun, in the South, heat can make the plants bolt too early. If you have a garden spot that receives alternating amounts of shade and sun throughout the day, that might be the place to attempt to grow your broccoli.
Broccoli requires nitrogen for good growth, but too much nitrogen can cause hollow stems (as can a boron deficiency). Use a balanced organic fertilizer to feed your plants. Heads with hollow stems are still edible.
When you begin to see a flower head emerging from the center of the plant, keep an eye on it daily. The flower head can go from barely there to overly mature in just a matter of a day or two. You want to harvest the head while the buds are still tightly closed. If the buds begin to swell or show yellow, cut the head off right away, no matter how small it is. You’ll find that your broccoli heads are smaller than those you get at the grocery store, but don’t be disappointed. You’ll be amazed at the difference in taste between those sold in the grocery store and what you get out of your garden.
Once the center head is cut, side shoots will begin to grow. Harvest those as you do the head.
Some of the possible pests that can be harmful to your plants are caterpillars, which include cabbage worms, cabbage loopers, cutworms, and army worms. Flea beetles are also a nuisance. Place tinfoil collars around the stems of your plants at soil level. Apply a Bt solution to the plant every 7 to 10 days, and of course, hand pick off those that you see.
Cabbage root maggots are the larvae of flies and are the size of a grain of rice which feed on the roots. To keep them from hatching, firm the soil well around each seedling. Applying a tinfoil shield at the base of the stem and then covering with mulch will prevent the adult flies from laying eggs in the soil.
The clubroot fungus causes wilted, discolored leaves and the roots are a gnarly mess. Most clubroot fungus is brought in from purchased transplants, so growing your own seedlings should help avoid this. If you find plants with the fungus, pull them out and destroy them. There’s nothing that can be done or any corrective measures taken to save the plant. Avoid planting any brassicas in the affected section of the garden for at least 4 years. Clubroot prefers acidic conditions, so adding lime to acidic soil at least two months before planting can help prevent the fungus.
Damp, hot conditions can cause a host of problems, including downy mildew, powdery mildew, grey mold, and bacterial soft rot. Insure your plants have adequate spacing with plenty of air circulation. Avoid watering your plants in the evening and don’t soak the plant itself. Instead, water around the perimeter of each plant.