Onions & the Solstice

Last week's Summer Solstice marked an important time of change in the onion row. For those of you who don't know, onions are sensitive to the length of daylight. When the days are growing longer in the Spring, onions focus all of their energy on producing green leaves. This is particularly important, because each leaf is responsible for one layer of the onion bulb. The more leaves, the bigger an onion you will harvest. Now here is the cool part. As soon as we pass the Summer Solstice the onion changes its game plan and begins to store all of the energy in the leaves down into the bulb. What really amazes me is how soon after the Solstice you can see it happening. In the picture above you can clearly see at ground level that the red "Mars" bulb is starting to thicken. I can't perceive the shortening of the daylight hours yet - thank goodness! - but my onion can. How amazing is that! One important disclaimer. Everything I have mentioned related to northern onions. For those of you in the South, you need to buy southern varieties of onions. They respond in reverse to daylight conditions, so they are perfectly suited to growing in your zone at a different harvest time. Do you have onions in your vegetable patch this year?

A bulb starting to thicken on a "Yellow Storage" onion.