How to Tell When Onions are Ready to Harvest

Onions curing after harvesting

I’ve grown onions for decades, but it wasn’t until a few years ago I found out how to pick them at just the right time. Pick them too early and they lack in flavor; pick them too late and they wind up mushy and with no shelf life.

Figuring out when to harvest onions isn’t as easy as it sounds. Gardening books weren’t much help because however they described knowing when to pull the onion either made no sense (“late in the season when the first set of leaves has expired and the second appears to wilt”) or meant nothing (“pull when ready”). Fortunately, I know Alfons, the guy who runs the onion farm right around the corner from me.

So how do you know when are onions ready to harvest?

Green Onions

Green bunching onions ready for harvest

According to Alfons, if they’re the fresh eating type — scallions, bunching, shallots, leeks, etc. — when the white upper portion of the bulb starts to emerge from the soil, the plants are ready to harvest. Since these types don’t store long after being harvested, if you’re getting too many all at once, you can actually prevent them from getting overripe and trying to flower for several weeks by mounding soil around the base of the onions, and waiting for the white to emerge again (a process called blanching).

Bulb Onions

If you’re growing the standard bulb / dry storage type, Alfons says wait until they start to look “tired.” That is, the crown of the onion bulb should be coming out of the soil, and the first layer of skin and leaves should be dry and papery. The upper leaves should still be green and firm but tall enough that they can no longer support themselves and droop, fold or fall to the side. This photo shows Utah Sweet Spanish onions ready for harvest:

Sweet Spanish onions ready for harvest

When harvesting, if you’re planning on storing them, you need to let them cure before putting them away. Alfons’ crew simply pulls them out of the ground and leaves them on the rows for two or three days to dry before sending them to the warehouse for cleaning and removal of the leaves and roots.

If you’re like me and can’t stand an idle raised bed during peak growing season, you can pull the onions and place them on a rack to cure. Once they’ve dried for a few days, the roots should shrink. Snip them off and allow the tops to completely dry out before removing them and storing the onion.

If you’re good with braiding (I’m not), you can leave the tops on, braid them while still green and hang them up to dry and store.

So there you have it. Harvesting onions at the perfect time is easy once you know what you’re looking for. (And if you share this, thank and onion farmer!)