Onions are often described as “Humble”, but they are actually sophisticated world traveling gourmands: grown all over the world not for mere sustenance, but rather to make other foods more flavorful and enjoyable. Their ubiquity makes them relatively abundant and affordable thanks to thousands of years of breeding and adaptation by farmers and more recently, plant breeders.
Like most food crops, onions are sensitive to the weather and the time of year. They can withstand a certain amount of cold, although they can’t handle long periods of freezing weather. But they are also extremely sensitive to geography: specifically, they are sensitive to the amount of sunlight that hits them and how it changes. This is what determines when or if they form a bulb. Different types of onions must be grown in areas depending on how long the days are. “Short Day” onions are grown in southern areas with little or no variation in daylength over the course of the year. “Long Day” onions are grown in the summer in northern areas where the days are much longer in winter than they are in the summer. If you plant the wrong type of onion or plant them at the wrong time of year, they may simply fail to make bulbs but still be edible (like leeks). Or, they may bolt to seed and become inedible.
Terra Firma is in a narrow swathe of the globe where it is possible to grow onions for most of the year. However, in any given winter, it might get too cold — killing the plants entirely. Alternately, it might get cold and then warm, and then cold and warm again. This causes the onion to bolt to seed. Finally, there are winters when long periods of wet weather cause outbreaks of disease that are difficult for us to control, or keep up from being able to control weeds.
But growing onions here in the spring for summer harvest means they have to endure our hottest time of year. Onion leaves don’t provide tons of shade for the bulbs, which are vulnerable to sunburn. And hot weather increases bug populations that damage the leaves. Most “long day” onions are planted in areas with much cooler summers than ours, so the plants are not well adapted to the heat.
So-called “Intermediate Day” onions are well-adapted for our area in that they mature in early summer. But they must be planted very early in the spring, when our area traditionally experiences our wettest weather periods. These varieties are more typically grown in the San Joaquin Valley around Fresno, which generally gets a fraction of the winter rain we receive (although this year Fresno actually got more rain than Winters).
For all of these reasons, there aren’t lots of onions grown in our area for food. Instead, onions are more commonly grown for seed. Planted in early fall here, just about any type of onion will reliably flower and produce seed in late spring and early summer. Driving in the country in May and June, it’s common to see large fields of flowering onions. Still, we have successfully grown both fall- and spring-planted onions over the years by finding particular varieties that seem to be able to handle the combination of cold and heat that we experience. But as the weather has become more extreme thanks to climate change, growing onions has become more challenging all over the world, and our farm is no exception.
We consider onions a critical component of our CSA boxes, as they are an important item in most people’s kitchens. By doing several plantings a year, at intervals of a month or so beginning in October and going all the way into May, we spread out the risks. Harvesting the onions with their greens on as “Spring Onions” while they are growing is another way we manage the risk. Most years we end up with at least one field that does not produce usable bulbs; in a bad onion year, we lose several fields. But we still end up having onions in your boxes for at least 4 months each year.
We began harvesting our first “short day” bulb onions last week. We also just finished planting the last of our “long day” onions: a new variety we discovered last year that is well adapted to extreme heat that should allow us to extend our supply of bulb onions well into the fall from a harvest in late August. While the hot, dry weather here has been challenging for other crops we’re harvesting right now, it is perfect for the onions and we expect this year’s season to be one of the longest we’ve ever had with great quality bulbs.