Broccoli grows well in soil temperatures between 65 and 75 degrees Fahrenheit. Accordingly, spring and fall planting work most effectively for growing broccoli. If soil temperatures rise above 75 F, prune broccoli to prevent the plant from bolting. Bolting -- producing yellow flowers -- is the plant's response to warm soil. With regular pruning, you can prevent flowers and harvest tender broccoli florets.
Watch for green buds in the center of a broccoli plant. Buds develop first in the center of the plant. By pruning the center head first, the plant will not bolt as quickly and it will continue to produce buds.
Prune the broccoli plant by removing the top 6 inches of the central stem. Cut the central stem off 6 inches from the top with the pruning shears when the buds finish developing but before they open and separate into yellow flowers. Use the harvested central stem of broccoli.
Watch for side shoots of buds after pruning off the central stem. Prune away all buds before they open and separate into flowers to prevent bolting and keep the plant producing for as long as possible. Use all buds you remove.
Many types of insects eat broccoli and cauliflower. Cabbage worms, aphids, cutworms, cabbage maggots, caterpillars, flea beetles and diamondback moths all infest and damage broccoli and cauliflower crops. In some areas, deer also munch on these crops from vegetable gardens.
Insect infestations often cause severe damage to the plant leaves as they eat the plants. The University of Minnesota Extension explains that cabbage maggots can eat cole crop roots, killing or severely damaging the health of the entire plant. All types of insect or animal pests that eat cabbage and broccoli reduce yields and make the crops less attractive.
Gardeners can keep deer away from cabbage and broccoli with mesh netting or tall fences around the vegetable garden. Gardening stores sell ladybugs, which feed on aphids and other insect eggs. The University of Minnesota Extension and University of Florida Institute of Food and Agricultural Sciences both suggest using an insecticide carefully in accordance with the package instructions to get rid of severe infestations.
Broccoli needs about 1 to 2 inches of water each week during the growing season, notes the Utah State University Cooperative Extension. During wet and rainy periods, rainfall may meet these needs. When it does not, you must irrigate the plants to ensure they get enough water for proper growth and development.
For best results, water broccoli with deep occasional irrigations as opposed to more frequent but shorter waterings. When rainfall does not supply all the water needs, water your plants once a week. For example, if your area has received a 1/2 inch of rain, you'll need to water the plants so they get an additional half to 1-1/2 inches.
Spreading mulch around your broccoli plants can help keep the soil moist and allows it to remain cool and prevent excessive evaporation, according to Ohio State University Extension. In addition, mulch can help prevent weeds. Use an organic mulch such as straw or grass clippings, and wait until the weather warms up before applying it.
Improper irrigation -- including too much, too little or uneven watering -- can make broccoli plants susceptible to some diseases. For example, overwatering these plants can cause a fungal condition called downy mildew, notes Minnesota University Extension. Gray leaf spot and black leaf spot -- two more fungal conditions -- can also develop as a result of improper watering techniques such as overhead watering.
Fill 3-inch diameter seed pots with potting soil. Leave a ½ inch space between the soil and the pot's rim.
Sow two broccoli seeds per pot, placing them on the soil surface. Cover the seeds with a 1/4-inch layer of fine-textured soil.
Fill a tray with water. Set the pots in the tray and leave them to absorb the water from the bottom. Drain the excess water out of the tray once the soil surface in the pots becomes moist.
Cover the pots with plastic wrap. Set them in a cool room that doesn't receive bright, direct sunlight. Broccoli germinate best at temperatures near 55 degrees F, according to the University of Missouri extension.
Remove the plastic wrap once the broccoli seeds germinate and sprouts emerge. Germination usually occurs within one week of sowing.
This depends on the crop you would like to grow. Vegetables such as broccoli, cauliflower, kale and collards can do well during colder months. Crops should be planted in early to mid fall for a late winter or early spring harvest.
Fill the planting container with a well-draining potting soil. The University of Maine Cooperative extension advises planting one broccoli plant in a 5-gallon pot, or three plants in a 15-gallon container.
Plant the broccoli seedlings into the container at the same depth they are growing at in their nursery pots. Space multiple plants in the same container at equal distances apart.
Water the container with a starter-fertilizer solution, following package application instructions. Water until the excess moisture begins draining from the bottom of the container.
Check the moisture in the soil daily, as containers dry out more quickly than garden beds. Water when the top 1-inch of soil begins to feel dry.
Fertilize the broccoli plants once a week with a soluble, balanced fertilizer. Apply at half the rate recommended on the label.
Chinese Broccoli / Kale
Gai Lan, White Flowered
Not only should you NOT substitute broccoli for Gai LAN in Chinese recipes, but you SHOULD substitute Gai LAN for regular broccoli in many recipes because of its wonderful flavor. Gai LAN is easier to grow than broccoli because it withstands heat better. We have chosen White Flowered Gai LAN because it will handle considerable heat, and in some climates can even be grown in the summer. Beef and broccoli stir-fry never tasted better than with Gai LAN Can also be steamed or boiled. Harvest the thinnings for a quick-cooking gourmet delight.
When to Sow Outside: As early as the soil can be worked.
When to Sow Inside: Six weeks before transplanting outside, or 3 to 4 weeks before last frost.
Seed Depth: 1/2"
Row Spacing: 12"
Days to Emerge: 10 to 20
Thinning: When 2" tall thin to 4" to 6" apart
Select one or more of the strongest looking broccoli plants in your garden from which to save seed.
Allow the plants to mature past the edible stage of growth.
Allow the plants to flower. The flowers will be small, with yellow petals.
Remove the silique, or seed pod, when they form on the stalks. Place the silique on newspaper, turning several times a day, to dry thoroughly.
Break apart the seed pods and collect the seeds inside. Work over a clean sheet of newspaper so the seeds will not scatter.
Place the collected, red-brown to black, seeds in an envelope. Seal the envelope and label with the contents and date.
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