Storage Tips for Winter Vegetables

Posted: October 9, 2012

The demand for locally grown produce continues to rise in Pennsylvania, providing excellent opportunities for producers to extend their marketing season in the fall and winter. Proper storage management in vegetables such as winter squash, onions and carrots will result in less decay, fewer losses and more high quality product to sell to eager consumers during the cold months.

Only clean, mature, and undamaged vegetables should be placed into storage. Quality cannot be improved after harvest; it can only be maintained. Injured, damaged or diseased produce loses moisture and decays more rapidly than healthy, undamaged produce. Maximize storage life by holding each produce item in its optimum temperature and relative humidity range.

Winter Squash: Store only mature winter squashes, indicated by hardness, color and stem corking. Curing may help harden rinds, but is not recommended for acorn types. Cure by holding winter squash at 80-850F and 80-85% relative humidity for ten days. After curing, store winter squashes at 55-590F (50-550F for green rind types), and 50-60% relative humidity. Winter squash may quickly show symptoms of chilling injury if held below 500F. Expect transpiration losses on the order of 1-1.5% per week. Most winter squashes store well for two to three months; a little less for acorns and a little more for hubbards. Ethylene exposure may fade color in green rind types.

Onions: Proper curing after harvest is essential for high quality storage onions. Onions can be cured in or out of the field, with or without the use of forced air. Whatever method is chosen, necks must be completely dry before placing onions in storage. Once in storage, onions should be held as close to 320F as possible, but not below. A relative humidity of 75-80% results in the best scale (onion skin) color. Under excellent storage conditions, onions can store 6-9 months, but 3-6 months is more typical. Exposure to ethylene encourages sprouting.

Carrots: More mature carrots will store longer than less mature ones. Like onions, the optimum holding temperature for carrots is 320F but not below. Carrots are prone to water loss, so relative humidity should be 98-100%. However, avoid conditions that allow free water to collect, as this will speed decay. Carrots can be stored for 3-5 months under good conditions. Exposure to ethylene in storage results in the development of bitter flavor compounds, so do not store carrots with ethylene-producing items.

Beets: Tops should be removed close to the bulb, and any damaged roots removed. The storage temperature should be around 320F but not below, and relative humidity maintained near 95% to minimize shrinkage. Beets can be stored for several months under proper conditions.