Transplant cucumbers before they outgrow their containers and after the last frost in the spring, which usually occurs anytime in May or June in the Northwest.
Incorporate several inches of compost or well-rotted manure into the soil bed, about 8 to 12 inches deep. Also mix in a complete fertilizer, using the rates listed on the label. Grow cucumbers in full sun.
Water the cucumber plants the day before transplanting. Water them until the soil is completely moistened.
Take the cucumbers out of their containers and plant to the same depth outdoors as they were in the containers. Space them 8 to 12 inches apart, with 3 feet between rows. Or, if you are using the hill system, plant about 3 cucumber plants per hill with hills that are spaced approximately 6 feet apart.
Water the transplanted cucumber plants with 1 inch of water if rainfall is not expected that day. It is likely, though, that in the Northwest during springtime it will rain enough, so check the forecast to avoid overwatering your plants.