|Broccoli (Brassica oleracea) in flower (photo credit)|
It is the large immature flower head of the broccoli that we harvest as a vegetable. Broccoli flowers develop on branching stems giving it the look of a green tree. It is this tree-like appearence that will entice some young ones to give it a try. (Have you ever fed your young ones a raw 'broccoli tree'?) For those of us in the northern parts of the country, broccoli is a wonderful addition to our diet, especially in the winter, as it is high in both vitamin D and A.
Broccoli tolerates cool soil and air temperatures and so can usually be planted a couple of weeks before the average last spring frost, and is among the first vegetables that can be started indoors in preparation for spring planting. See my spring Seed Starting & Planting guide to help you know when you can first start cabbage or other plants in your area. Not only do broccoli tolerate cool early spring temperatures, but most varieties do not like hot summer temperatures (starting between 75F & 80F and up) and will bolt (flower). If you anticipate that your plants will be exposed to warm temperatures plan ahead and plant bolt resistant varieties.
Plant broccoli in full sun and well drained soil. If you plan a fall harvest and have a long enough growing season, you can directly plant seeds in the soil, or started broccoli can be hardened and transplanted into the garden 2-3 weeks before the last spring frost. Individual plants should be placed about 18inches apart or one per square for a square foot garden. Be sure that the plants receive the equivalent of 1 inch of water per week for the best production. Harvest when the heads are full and compact. If the flowers begin to show signs of opening, harvest immediately. Side shoots will develop smaller heads after the primary head has been harvested, extending the season for several more weeks.
Happy Gardening! :)