- Prepare the soil in a partially shaded area that receives three to six hours of sun every day. Test the soil and add limestone to raise the pH level, if necessary. Spread a 2-inch layer of compost over the soil and work in the compost until you have an 8-inch layer of rich, tilled, well-drained soil. Work in 1 to 2 pounds of 10-10-10 general purpose fertilizer per 100 square feet of planting space unless soil tests indicate otherwise.
- Transplant broccoflower plants two to three weeks before the last frost date for a spring or early summer harvest. Dig a row in the prepared soil deep enough to cover the broccoflower root crown and long enough to space the plants 24 inches apart. Place the plants in the row, press the soil around the root crowns and water thoroughly. Additional rows should be 24 to 30 inches apart.
- Keep the soil evenly moist throughout the broccoflower growing season. Apply 2 to 3 inches of organic mulch to keep the soil moist and cool. Provide 1 inch of water each week in the absence of rain, and do not allow the soil to dry out. Apply a thin strip of 10-10-10 fertilizer along one side of each row three to four weeks after planting.
- Cover the plants with row covers or newspapers if the temperatures drop below 50 degrees. Broccoflower plants can develop small, premature heads in cold or dry conditions.
- Monitor the broccoflower plants for diseases such as downy mildew, which causes stunting and weakening, and pests such as green and yellow cabbage worms, which chew large holes in the leaves. Remove diseased plants and avoid over watering to control diseases. Remove pests by hand or apply products that contain Bacillus thuringiensis (Bt).
- Harvest the broccoflower when the head measures 6 to 8 inches across. Cut the heads from the main stem and leave at least two green outer leaves on the head. Harvest while the heads are firm and compact and before you can easily see individuals florests.
- Transplant new broccoflower plants in August for a fall harvest or sow seeds directly into the garden in September or October for a winter harvest. Plant the seeds 1/2 inch deep and 3 inches apart, and thin the seedlings to 24 inches apart. Continue care as described above.
