Overwintering onions on our fort wayne farm

This is a a deep dive into one of or staple crops that transports us to a time of cold fingers, long winter shadows, and freezing water lines. Onions have been tricky for us in the past. They are one of the more labor-intensive crops to transplant and are susceptible to a myriad of diseases. They enjoy a long, cool spring to grow their green tops followed by a hot and dry summer to size up their bulbs. If you have been following Indiana springs over the last several years, you know that “cooler” springs are increasingly rare, and our humid summers facilitate a lot of disease pressure.


In order to get an earlier crop and to avoid the weather issues, we have taken to a new schedule. Since 2022, we’ve planted onions in the late fall, overwintered them in an unheated greenhouse, and harvested them in June just in time for our first Fort Wayne CSA pickup.

While all onions are extremely hardy in cold weather (they can survive outside uncovered just fine), they are especially sensitive to daylight hours. This means they “bolt,” or flower and set seed, after the winter solstice. Therefore, it’s the lengthening days, not the cold, that’s a concern for overwintering onions. Luckily, these onions have been selected to withstand bolting and have been reliable for us going on three years now.


We start the onions from seed in early September and plant them in late October after the first frost and following tomatoes. They are essentially dormant all winter, growing only after Valentine’s Day, when we get over 10.5 daylight hours. The warmer temperatures in March and April bring rapid growth to the tops, while the bulbs begin to grow in May. By early June, the leaves have flopped over, indicating that they are ready to harvest for our Fort Wayne farm share. 


Note that we grow our onions in clusters, which saves time planting; the bulbs simply push away from each other as they grow under the weed mat. Bonus points if you recognize the tall plants in the background of this photo. That will be a topic for another time.