As you know, I grow a lot of long-day onions from plant starts purchased from Dixondale Farms. They grow great for me and I know other local gardeners who've had amazing results, too.
Their website has a lot of useful onion-growing information on it. I just discovered three items that I thought you would find helpful. I had no idea that you should harvest the onions that flower right away! Read on...
Q. My onions are growing flower stalks. Why are they doing this, and what should I do about it?
A. This process is known as "bolting," and it means that the onion bulb won't get any larger. You should immediately harvest it; otherwise, the continued growth of the flower stalk will make the bulb inedible.
So why is the plant bolting? It's been convinced by the weather that it's time to go to seed. Onions grow out a bulb the first season, and go to seed the second. We harvest and eat most onions before they start the second growth stage.
But cold weather, alternating with warmer weather, causes them to flower early -- especially if it rains more than normal. These conditions have prevailed over much of the country this year, so keep a close eye open for bolting. You may be able to enjoy bolted plants as green or salad onions if you harvest quickly enough.
Item #2: Onions and other commercially
cultivated alliums are biennial plants, which means that it usually takes them
two growing seasons to go from seed to seed. The first season is when we take
it from a seed to a transplant. When you plant the plant, it begins its second
season. Given a certain set of environmental conditions, onions can be tricked
into believing they have gone through two growing cycles during their first
year. Instead of finishing with a well-cured bulb, ready for the market, a seed
stalk can develop prematurely, causing onions to be unmarketable. While it is
impossible to control the weather, planting at the correct time for the variety
in question is the most important factor to limit premature bolting.
Over-fertilizing can also contribute to bolting - if onions are too vigorous,
too early in their development, bolting can result. Onions bolt as a
reaction to cold weather stress. Temperatures under 45F may cause the onion to
bolt when the plant has five or more leaves. Some onions are more or less
susceptible to bolting than others and the process is not completely
understood. Unfortunately once the onion does bolt, the quality of the onion
bulb deteriorates rapidly and it should be harvested and eaten as quickly as
Item #3: Because the onion is a biennial,
it takes two years or seasons to go to seed. However, this process can be
altered by temperatures, transplanting or both. An onion plant’s first
life begins in the seed beds. When transplanted, the onion begins its
second life. When the plant has five to six leaves or more and experiences an
extended period of cooling temperatures, it can go dormant a second time.
Once it attempts to start a growing again (its third life) and the temperatures
rises, the plant believes that it is going to die, so it tries to reproduce and
grows a flower. Occasionally other factors, such as excessive stress, may
cause bolting, which explains why only a few plants may bolt in the entire
field. Should this happen, the onion is perfectly edible, but the
ring associated with this leaf will rot, so it is best to eat the onion right
away. Don’t bend or break the onion top; the leaf is hollow and is more
than likely the center of your onion.
All information above was graciously provided by Dixondale Farms.