(Brassica oleracea gemmifera) Romans grew the ancient precursor to Brussels sprouts as far back as the 1200s. The plant as we know it today was developed in Belgium and the French introduced it into the U.S. in the 18th century. Brussels sprouts love cool weather and can tolerate frost, but they cannot handle excessive heat and struggle in temperatures above 75 degrees F. For regions with hot summers and mild winters, they perform well when grown over the winter. For those with harsh winters, try planting very early in spring and again in midsummer for a late harvest. Sow seeds ¼ inch to ½ inch deep, ideal germination temperature is 70-75 F. Seeds germinate in 8-10 days. Start seeds indoors 8-12 weeks before the last frost date and set plants out just after last frost, 24 inches apart. If you have a long mild season you can also try to direct sow. Plants prefer rich soil with full sun and abundant moisture. They are best when harvested after a light frost.