CORVALLIS – Fresh vegetables can be harvested most of the year in many places in Oregon. In fact, many cool-season crops produce well in the fall and hold through the winter if protected.
"You can plant vegetables in mid- to late summer after you harvest spring crops and as space is available," said Pat Patterson, Oregon State University Extension Master Gardener in Lane County.
Some of the best vegetables are produced during the warm days and cold nights of fall, she said. Frost adds sugar to sweet corn and crispness to carrots. Parsnips, kale, collards, Brussels sprouts and Jerusalem artichokes also improve with a touch of frost.
Succession planting is easily accomplished west of the Cascades, but east of the mountains, newly planted crops may need a cloche or cold frame to keep plants alive into the colder months and as protection against rain battering.
Certain vegetables are better suited to fall and winter harvest than others, and a complete list of recommended varieties and how to grow them can be found in the eight-page OSU Extension publication PNW 548, available free of charge online.
A key to successful fall or winter gardening is location of your garden. Choose the warmest garden spot you have that is not prone to early frost, such as at the bottom of a hill or a windy area. A south-facing slope is best for winter sun. Be sure to restore nutrients removed by spring and summer crops with a light layer of compost or aged manure or a small application of fertilizer. Do not over-fertilize with nitrogen.
"During the rainy season, good drainage is essential," Patterson advised. "Raised beds are best, and if your soil doesn't drain well, amend it with organic matter such as compost."
Timely planting is another key to success. Crops need time to become well-established before cold weather and short days curtail growth, but if you plant too early, the young plants can wilt in the heat or mature too soon. Choose the fastest-maturing varieties and pay attention to the average date of the first killing frost in your area. Most winter crops are planted from June to early August.
You can give seeds a head start in containers or a nursery bed, or buy starts from a garden center.
Examples of summer-into-fall plantings:
- Pull out old pea vines and plant carrot seeds in their place;
- Yank bolted broccoli and replace with a crop of lettuce and salad greens;
- Harvest the rest of the beets and sow a crop of kale;
- Replace tomatoes in the fall with an overwintering crop of garlic or shallots;
- Remove your spent squash plants and put in crimson clover (a cover crop) to protect the soil over the winter;
- Compost bitter lettuce and replace with a batch of scallions, leeks or radishes.
Patterson advises that a crop that fails one year because of an unusually early freeze or abnormally cold winter may thrive in a milder year. "Be willing to experiment, she said, "and don't give up if your results some years are less than ideal."
If you'd like to build a raised bed cloche to extend the gardening season, you can download directions free of charge in OSU publication EC 1627-E online.