You can plants seeds directly for both broccoli and cauliflower from mid-July to September or you can transplant them from early August to early September. If you plant them from seed, you will see transplantable vegetables in about four to six weeks.
Keep broccoli and cauliflower well watered and fertilized with appropriate fertilizer (8-24-24 or 13-13-13, five to six pounds/pints per 100 feet of row). Additionally, side-dress plants with 3/4 pound (1 1/2 cups) of ammonium nitrate per 100 feet of row 3 to 4 weeks after planting and again 2 weeks after that.
Recommended varieties are below…
Broccoli: Arcadia, Gypsy, Diplomat, Packman
Cauliflower: Majestic, Candid Charm, Cumberland, Snow Crown, Freedom
Information from Horticulture Hints, Summer 2011, LSU AgCenter