Cold-Hardy Vegetables To Plant That Could Tolerate Oregon Winters

Now officially in the fall season, winter is just around the corner in Oregon. But it’s still possible for avid gardeners to get busy in their gardens in the cold weather- and plant a few vegetables in winter that can be harvested in spring.

But don’t dilly-dally- there’s work to be done before home-grown veggies appear on your family’s plates.

Winter Gardening In Oregon

A plant breeder and researcher at Oregon State University (OSU), Jim Myers says winter gardening is a risky business. What works in a year when the weather is mild doesn’t work the following year if the weather gets more severe.

According to Myers, some cold-hardy vegetables- depending on the crop, planted between mid-August and early October can render a harvestable crop in spring, but this differs from year to year. Farming is somewhat of a gamble.

Hardy plants don’t necessarily get killed off by cold weather, but their growth rate slows significantly. Growth doubles for every 18° of temperature rise, but only when the temperatures range from 40° to 98°. Sometimes, vegetables survive a cold winter without reproducing but could still mature in spring.

Vegetables That Can Withstand Low Temperatures In Oregon

The hardiest vegetables- those that can withstand heavy frost associated with air temperatures below 28° include:

• Arugula
• Austrian winter pea
• Broccoli
• Brussels sprouts
• Cabbage
• Collards
• Corn
• Fava beans
• Garlic
• Kale
• Kohlrabi
• Leeks
• Mustard greens
• Onions
• Radish
• Rhubarb
• Rutabaga
• Spinach
• Turnip

Semi-hardy vegetables- those that can withstand light frost of air temperatures between 28° and 32° include:

The outer leaves of these crops that form a head may die under colder temperatures, but these can be peeled away to reveal the undamaged head inside:

• Cauliflower
• Celery
• Chard
• Chinese cabbage
• Endive
• Garden pea (before flowering)
• Lettuce
• Parsley
• Radicchio

The roots of these vegetables will tolerate light frost temperatures but the tops will die:

• Beets
• Carrots
• Parsnips

Vegetables that are more resistant to winter rain rot tend to contain the pigment anthocyanin, which gives them a vibrant red or purple color, Examples are purple-sprouting broccoli, Rosalind broccoli, and purple kale.

The USDA Plant Hardiness Zone Map is a useful tool to help find your hardiness zone and plant accordingly.

Tips To Help Plants Survive An Oregon Winter

Snow provides insulation and prolonged snow cover acts as insulating mulch, warming the soil for the cold-hardy plants. The worst Oregon winters are associated with rain rather than low temperatures, making protection crucial for the survival of your crop.

Vegetables could be covered with high or low tunnels made from clear plastic over metal hoops or row covers or cloches can be placed over plants. Mulch to warm the soil could be made from yard debris, cardboard, or newspaper.

The OSU Extension Service recommends several ways to guard your landscape from frigid conditions, including:

• Don’t walk on the lawn: If there is no snow insulating the grass, walking on frozen grass can break the leaf tissue and damage it.
• Knock the snow off branches and wrap rope around them: although snow is a good ground mulch, tying the branches upward helps restructure them to a more upright position before the storm and helps prevent snow from weighing down branches, especially frailer varieties like cypress, young rhododendrons, and azaleas. Or shake the snow off branches to keep them from being damaged.
• Don’t water your plants in freezing conditions: Shrubs underneath the eaves of a house are susceptible to drought damage and should be watered deeply every six to eight weeks- but it should be done early in the day and only when the air temperature is above freezing.
• Protect container plants as the pots can freeze: Pull into a garage, unheated garage, basement,  greenhouse, or similar site where temperatures stay above freezing. Alternately, safeguard potplants by covering them with materials that can help insulate them and wrap pots in bubble wrap. Hanging plants should be placed on the ground and covered.
• Keep the greenhouse above 35 degrees: Most inside plants are likely to survive.
• Insulate tender perennials with mulch: Using compost, leaves, conifer branches or other organic material mulch helps protect the root systems of hardier varieties such as fuchsias, roses, clematis, agapanthus, and dahlias. A tomato box can be built for plants that need extra help by wrapping burlap around the outside of the cage and securing it with bungee cords, ideally in a square formation. Fill with straw or leaves but don’t forget to remove the material when the temperature goes up again.
• Consider how trees reacted in previous winters: Most trees are dormant in winter and can withstand below-freezing temperatures but non-native trees don’t have the same cold tolerance. Check labels before buying and plant trees with cold hardiness appropriate to your area.
• Brown freeze streaks and damage on the leaves do not necessarily mean the plant is dead: While cold weather will likely cause a lot of leaf and tissue damage and frost damage can make leaves turn dark brown or black or appear water-soaked or shriveled but the inside may still have survived the winter.

There’s more information on the United States Department of Agriculture’s website.