Broccoli is fairly easy to grow provided you understand that broccoli is a cool-season crop, and is not designed for summer temperatures. Before planting make sure that the soil is amended with plenty of compost or well-rotted manure. You can also fertilize with a well-balanced fertilizer, like 5-5-5.
Start your seed indoors about 6 weeks prior to last frost, or sew directly into your garden in late February (Ohio). Plant one seed every 4-5 inches and cover with about ¼” of soil. Thin to 16”once plants have reached 3” in height.
Once the seeds are in the soil you need to water GENTLY, as the seeds can easily be washed out of the soil.
As your seeds begin to sprout it is important to understand that broccoli is a very thirsty plant. Water liberally.
One of the hardest parts of growing broccoli is deciding when to harvest. The plants are ready to cut when the buds are dark green, tight, and about to open up. Once it starts flowering you are too late. Be aware that flowering occurs quite quickly when daytime temperatures are in the high 70’s, so plan accordingly.
I find that I have the best success with fall crops. I sew my seeds directly in the garden during August and harvest in November. Fall broccoli will easily tolerate temperatures into the mid 20’s and will continue to produce here in Ohio well after Thanksgiving.