Onion Tops Falling Over: A Sign of Harvest Time
Onion tops falling over in mid to late summer is usually a good sign. University of Minnesota Extension says to harvest when about half of the tops have fallen over. It also advises stopping watering once the tops begin to fall. The bulbs are nearly ready and the work shifts to drying.
The short answer
When onion tops start to fall over, stop watering. Once about half the tops are down, lift the bulbs. Dry them somewhere warm with good airflow for two to four weeks, until the necks are tight. Then trim the tops and store the bulbs cold and dry.
Why do onion tops fall over?
As bulbs reach full size the tops bend down near the neck. Minnesota Extension calls this the main signal of harvest time. NC State Extension says onions can be harvested when two thirds of the tops have died down. Both describe the same stage. Other stress signs are covered in environmental stresses on weed plants.
When should you harvest onions?
Minnesota Extension says to stop watering when the tops begin to fall over and to harvest when about half have fallen. Check the soil first with checking soil moisture by feel. Iowa State Extension notes that bolting, when onions send up a flower stalk, is often brought on by stress such as cold weather. It says to harvest and use bolted onions promptly.
| Stage | What you see | What to do |
|---|---|---|
| Tops begin to fall | First leaves bend at the neck | Stop watering |
| Half the tops down | Tops down | Lift the bulbs |
| Drying | Skins dry and papery | Two to four weeks warm and dry |
| Necks tight | Tops dry | Trim and store |
Sources: University of Minnesota Extension, Iowa State University Extension, NC State Extension.
How do you dry onions for storage?
Minnesota Extension says to dry onions at 75 to 90°F for two to four weeks until the neck is tight. Iowa State Extension gives two to three weeks in a warm, dry, airy spot such as a shed. It suggests trimming the tops to about one inch above the bulb and storing onions at 32 to 40°F in mesh bags. Cleanup ideas for the end of the season are in fall garden cleanup after cannabis harvest.
How to: step by step
- Watch for the first tops to fall.
- Stop watering at that point.
- Lift bulbs once half the tops are down.
- Dry bulbs warm and dry for two to four weeks.
- Trim tops to one inch above the bulb.
- Store cold and dry in mesh bags.
Troubleshooting
Thick necks that will not dry: use these onions first.
Flower stalks: stress such as cold can cause bolting.
Sprouting in storage: the spot is too warm.
Kind Seed Co shares these garden notes for growers of all kinds. Mulch ideas for onion beds are in mulch for cannabis.
Sources
- Growing onions in home gardens, University of Minnesota Extension
- All about onions, Iowa State University Extension
- Allium cepa (onion), NC State Extension Gardener Plant Toolbox
- Harvesting and storing home garden vegetables, University of Minnesota Extension
FAQ
When should I stop watering onions?
Minnesota Extension says to stop watering when the tops begin to fall over.
How long do onions need to dry?
Minnesota Extension says two to four weeks at 75 to 90°F until the neck is tight. Iowa State Extension gives two to three weeks.
Why are my onion necks thick?
Minnesota Extension links large necks to too much nitrogen. Iowa State Extension advises using thick necked bulbs first since they do not store well.
How should onions be stored?
Iowa State Extension suggests 32 to 40°F in mesh bags. Minnesota Extension lists cold, dry storage with a shelf life of about four months.
Why are stored onions sprouting?
Minnesota Extension says onions tend to sprout when storage temperatures rise above 40°F.
