Most vegetables go through a series of life stages including vegetative growth, flowering, fruiting and senescence (aka, “death”). Our goal as humans — farmers, gardeners, and eaters — is generally to succeed in growing them until they produce the part we like to eat. But like all plants, a vegetable’s goal in life is to reproduce: to flower and then create offspring.
The happier a plant is, the more likely it will spend more time growing before it makes seeds. If it has the right weather, soil and amount of water, plants will seek to grow as much as possible before making seeds. Big, healthy plants can produce lots more seeds, thus achieving greater success in their goal of reproducing themselves.
Big, healthy plants also tend to make more of the vegetables that humans like to eat, whether that is leaves, roots, flowers or fruit. Our goal as farmers is to keep the plants as happy as possible, and then harvest the parts we eat.
When a plant that is insufficiently developed for humans to eat decides to go to seed, we call it “bolting”. “Bolting” has a negative connotation — it is not used to describe a crop with edible seeds or fruit, only one that does not. For example, if a carrot begins to go to seed before it is big enough to harvest, it is bolting. For a farmer, this can mean the crop is partial or even total loss.
Many common vegetables are triggered to bolt by either temperature changes or changes in the amount of daylight, or both. Almost all the vegetables we grow in the fall for winter harvest will begin bolting in late winter when they sense the onset of spring. But a cold spell followed by a week of warm weather can trick them into bolting a month or two early — effectively ending harvest.
Exposure to very cold temperatures when the plants are young can also cause vegetables to bolt. Overwintered onions in particular are sensitive to very cold temperatures when they have 4-6 leaves. We try to avoid this problem by planting the onions strategically so they are either bigger or smaller than the critical size in December, traditionally our coldest month.
But in the last ten years, the coldest weather we’ve had has been occurring earlier in the year. In 2013, we had a freeze on December 2nd that actually killed many of our onions completely. And in 2018, we had a freeze in mid-November that was compounded by the smoke from the Camp Fire that blocked out the sun for an entire week. It didn’t kill any onions, but it must have confused them.
The majority of our onions are now bolting. This renders them entirely useless as bulbs — the seed stalks that grow up inside the onion are tough and woody. The only onions that appear to have avoided this fate are the ones we planted after the freeze. That’s about a third of our total onion acreage.
It may not be a total loss. We have decided to keep one of the bolted onion fields and try to harvest the seeds. It’s our favorite variety — the Early Red Burger — and unlike all the rest of the onions we grow, it is open-pollinated and does not require special production techniques that hybrid seeds do. But that’s a topic for another newsletter.
Onion shortages might not seem as scary as killer hurricanes or rising sea levels, but they are just another way that climate change is going to disrupt human life. Terra Firma is not the only farm whose onions was affected by the cold weather and smoke in November. A large percentage of the onions grown in the state are bolting right now, which means there will be a significant shortage of onions in a month or so that will lead to higher prices for consumers. Lucky for you, our CSA subscribers get first priority on our onion crop. It won’t be as abundant as other years (last year, for example, was a bumper crop) but for most people it will still be plenty.