Plastic Planters Durable Plastic Pots in Large and Small Sizes Growing Dahlias from Seed (It's easier than you think) Sweet Valley Acres Bougainvillea plant care and fertilization 5 Reasons To Plant Onions in Fall + How To Do It Plant onion seeds indoors for a head start! Onions have a long growing season, and sowing onion seeds indoors will give you a leg up, which is particularly helpful if you live in a cooler climate.