What to do in your Northwest garden in April
Plant bare-root blackberries, grapes, hardy kiwis, raspberries, strawberries, and tree fruits while nurseries still have them in Sunset climate zones 1-3. Bare-root stock is gone, so purchase containerized plants.
Plant seeds or seedlings of chives, garlic chives, and parsley right away, but wait until danger of frost is past to sow basil and cilantro. Plant lavender, marjoram, mint, oregano, rosemary, sage, tarragon, and thyme seedlings anytime.
After snow melts and the soil starts to warm, plant lawns from sod or seed; water in well unless there's still a chance of snow or frost for zones 1-3. Bluegrass does especially well at higher elevations; perennial rye and fescue are good anywhere. Zones 4-7: Start lawns from sod or seed anytime. Keep the soil surface moist until the grass is growing at a rate of about 1 inch per week, then water deeply but less frequently.
In cold-winter areas in zones 1-3, bare-root stock is still available of trees, shrubs, and vines; buy and plant immediately. In zones 4-7, look for containerized flowering shrubs (azaleas, rhododendrons, and lilacs are blooming heavily now); flowering trees (cherries, crabapples, and dogwoods); and roses. All climbers from clematis to wisteria.
Plant broccoli, cabbage, cauliflower, chard, Chinese vegetables, kale, kohlrabi, lettuce, potatoes, radishes, rhubarb, and spinach. When danger of frost is past, plant beans, corn, cucumbers, melons, squash, and tomatoes.
Get woodland perennials like bleeding heart, columbine, Corsican hellebore, forget-me-not, basket of gold, evergreen candytuft, iris, rockcress, Solomon’s seal, sweet violet (viola odorata), sweet woodruff, wallflower, and wood anemone.
The shoulder season, when temperatures rise but it’s still too early to plant warm-season flowers, is a good time to put out small pots of blooming orange or yellow calendulas, English daisy, snapdragon, sweet alyssum, fragrant stock, and primroses. Violas also thrive now: In addition to the ones we recommend here, try new ‘Rain Blue and Purple’, a two-toned Johnny-jump-up.
When danger of frost is past, you can begin planting summer annuals, including calibrachoa, marigolds, pelargoniums, petunias, and zinnias.
Most vegetables start quickly from seeds on a windowsill, and squash and melons are among the easiest. Try ‘Honey Bear’ squash, a compact hybrid acorn type; and extra-early ‘Lambkin’ melon, whose 2- to 4-pound fruits have sweet white flesh. Both varieties are new All-America Selections winners that have performed well on both sides of the mountains in the Northwest.
As growth begins, apply a fast-acting liquid fertilizer to early spring-flowering plants and to vegetable and flower beds. You can achieve the same benefit with an organic fertilizer like blood meal. Give lawns a granular formulation of 2 pounds actual nitrogen per 1,000 square feet.
Cut tall grasses, such as fescue, bluegrass, and rye, about 2½ inches tall. Cut short, putting green-style grasses like bent grass about ½ inch tall. Mow often enough so that you never have to cut more than a third of the blade at once.