Happy Gardening! - CK
A: The short answer: 4-6 weeks BEFORE the average LAST frost date for your area. In Austin County, Texas, the average last frost of the winter is usually between February 8 - March 2. Using that date as a guide, the earliest recommended planting date for the Bellville area is the first week of December! However, most gardeners in our area like to get their onion sets in the ground in the middle of November, or as soon as they are available.
A: You're right! "1015" does indicate October 15.... but that is the date commercial growers plant the seeds in the Rio Grande Valley. If you intend to buy bare root onion bulb transplants (aka "sets"), then you have to wait until the seeds that the growers started are big enough. Growers pull seedlings to bundle, pack, and ship when the bulbs reach the size of a pencil. The growers do attempt early crops, especially because the demand for onions starts so early, but it still takes 4-6 weeks go from seed to pencil-diameter bulb. Occasionally the weather cooperates and the sets are available ahead of schedule, but typically crates of onions arrive in stores around November 10. Thanks to the heat in October, this year we expect them to arrive during the second week of November.
A: Any onion sets available earlier than late October are likely the wrong variety for our area, such as the long-day variety yellow or white Spanish. The Spanish onions grow well in the far north, store well over long periods, and are hotter tasting, but don't get the opportunity to develop properly here. In our area, short-day onions are the best type. Short day varieties include the 1015Y, Yellow Granex, White Granex, Vidalia, and Red Burgundy. Be especially careful that you purchase the correct day length onion if you choose to order online or through the mail.
A: As many as you want! Ha. For onion bulbs to fully mature, you'll need 4" of space between each bulb. With approximately 30 bulbs per bundle, each bundle of onions should plant roughly 10 feet of garden space. If you intend to harvest some earlier for green onions, you can plant them closer together. Consider how many onions you'll use within the expected storage period. Remember that short day sweet onions do not keep as long as hot onions.
A: Most likely, yes. Onion sets are in a dormant state when shipped, and dry is good. As long as they don't get wet, they will stay dormant and viable for several weeks. Even the saddest, driest looking bulbs will usually bounce back once planted. It is important to keep them dry and cool until planting, because moisture will disrupt the dormancy, initiate growth (which is only sustainable if planted), and possibly lead to rotting.
A: As stated above, the onions need to stay DRY and COOL. Do NOT water or moisten them, do NOT put in water or soil. The bundle may be opened to allow for better air flow: good ventilation is important. Moisture, even from the seemingly dry bundle, can cause the seedlings to rot.
A: For the best start, plant your onions into prepared soil with a fertilizer already mixed in. Use a 1-2-1 ratio, such as 10-20-10 or 12-24-12. About every 2-3 weeks after planting, sidedress the onions with a mostly-nitrogen fertilizer such as 21-0-0. Stop fertilizing when the bulbs start forming, which is indicated by the soil around the top of the plant cracking away.
A: Hands down, the Texas SuperSweet 1015Y. We regularly sell 2-3 times as many of the 1015s than any other variety. So, if you have to pick just ONE, pick the 1015!
Dixondale Farms http://www.dixondalefarms.com/onionguide
Aggie Horticulture http://aggie-horticulture.tamu.edu/archives/parsons/publications/onions/ONIONGRO.html
Texas Gardener http://www.texasgardener.com/pastissues/novdec05/onions.html
Growing Onions Organically http://www.rodalesorganiclife.com/garden/onions-keeps