When it comes to planting onions, getting them into the soil as soon as it can be worked is always the best time - but not because these veggies love cool weather. Bulb formation of onions is determined by the number of hours of daylight. Long day onions - the kind we grow in Maine - begin to form bulbs when the hours of daylight ranges between 15 and 16 hours. This means that onions in Maine begin to develop bulbs between the last week of May and the middle of July. When bulb formation begins, the tops stop growing and the plant channels its energy into forming the bulb.
What this means to gardeners in Maine is that if onions are not planted early they will not have time to grow healthy tops to produce the energy needed to form large juicy onion bulbs.
There are, of course, variations on exactly when your onions will begin bulb formation, depending on the specific onions you wish to grow. As a rule planting onions now will likely result in small onions, whereas those planted in April are likely to produce bigger bulbs.
If you didn't get your onions in until late, all is not lost. They can still be eaten as green onions or harvested whenever needed for your favorite recipe - just don't expect large onions in the fall.
Until next time ~ HAPPY GARDENING!
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