Fall-planted onions can survive well in low tunnels to produce very early spring bulbed onions. In this study, we evaluated several different varieties at different planting dates, to try to narrow down the best time of planting and to find new varieties (especially red ones) that will perform well in this system. We evaluated onions in high tunnels as well as in low tunnels to determine whether onions might mature much earlier in high tunnels.
We did find a couple of promising red varieties. Also, we found that varieties varied greatly in terms of sensitivity to bolting. Planting early increased the chances of bolting in general, but for the most bolting-resistant varieties, planting early resulted in earlier maturity and bigger bulbs. Access the full report for more details.