Western Washington has mild, rainy winters and cool summers that can be quite dry, ideal for some vegetables and a challenge for others. Some vegetables will stay green in the garden right through winter, while others find the infrequent summer hot spells too warm for their liking. The best plan is to use the advantages and work around the disadvantages.
In general, greens such as lettuce, swiss chard, kale, spinach and other plants with edible leaves do quite well in both summer and winter. Some are hardier than others, swiss chard and kale tolerating the most cold, but many may be grown under glass or plastic shelters.
Look for varieties appropriate to the season, heat-resistant ones for summer and cold-hardy for winter. Lettuce, for instance, can be found in both, as can spinach. Remember that spinach likes a neutral soil, so add lime to increase the pH of acid soil.
The Cabbage Family
Broccoli and cauliflower, both do well in cool springs, as do the various varieties of Chinese cabbage. Some are hardy enough to overwinter. For best results, start transplants yourself in early spring because nursery starts may not transplant well, leading to "bolting," premature head formation.
Peas and Beans
Peas are an excellent crop in this area, often planted around Presidents Day and well adjusted to cool springs. Beans do well if planted once the soil warms up. Try purple-podded varieties early in the season because these sprout better in cool soil than most.
Garlic is best planted in fall and will make good root growth during winter, leading to strong, healthy spring development. Onions can be treated the same way.
Potatos are a good choice for new garden beds because they prefer the acid soil that is common in Western Washington. They are usually planted in March.
Carrot, beets, and other roots crops are all appropriate for Western Washington, and can often be planted to overwinter.
Summer squash is a good bet, just wait until the soil warms up before you plant it. Seeds planted directly into the soil often do as well as transplants. Winter squash may do well if you have lots of sun and a warm situation, not too close to the water.
Heat Loving Risks
In ordinary summers, somewhat cool but with occasional spells in the mid-80s and above, tomatoes and corn may ripen quite well, especially if you choose extra early varieties. If the weather is cooler than normal, you may be disappointed. Eggplants, peppers and melons are only for sheltered, extra warm south-facing nooks, or greenhouses. You can always gamble on having a heat wave, but be prepared to lose.