Home & Garden

Gardening: April tasks for Northwest gardens

gardening by WSU Cooperative Extension
April brings clear spring life to the maritime Northwest garden, from the blooming spring narcissus and tulips to the sound of bird song in the morning. This month the tasks that make the summer garden thrive must be done!
   Add soil amendments to vegetable and flower gardens if it hasn't already been done. This is a good time to dig in finished compost from the winter's bin. Spread a layer 3-4 inches thick over the garden, then dig it in to be ready for planting. Compost added to planting areas for summer annual beds also gives the plantings a boost and helps to retain water through dry summers.
   Fertilize shrubs and trees in the landscape if it hasn't been done. Established trees may need very little fertilizer, but if shrubs are putting out very little new growth, fertilizer may help. Do not fertilize when the soil is dry; be sure to water the granules into the ground. Feed rhododendrons and azaleas, and be sure to keep them watered with at least an inch a week if April or May are dry months. Any fertilizer with a 5-10-10 ratio of nitrogen-phosphorus-potassium will work well in shrub borders. Follow label directions for quantities to apply. The best time to fertilize garden plants is when they are in active growth and can utilize the nutrients.
   Choose and set out new container plants from nurseries. Look for plants with intriguing spring bloom, such as the lily-of-the-valley shrub (Pieris japonica) or the bridal-veil shrub (Spirea, available in many species and cultivars). Check with your nursery advisor for plants that will, when established, be drought tolerant in maritime Northwest gardens. Some attractive spring-bloomers that tolerate dry summers, including the two mentioned above, are spring-bouquet (Viburnum tinus) and escallonia. All newly-installed landscape plants will need watering during their first one or two years in the garden, but many will then settle into tolerating dry periods. Selecting plants for water conservation is a wise way to plant, as the population in the maritime Northwest grows and water resources become more restricted.
   Check stored dahlia tubers, and sprinkle a little water on them if they are dried or shriveled. Most dahlia experts recommend planting them out in mid-May after soils have warmed a bit. Dahlias originated in Central America and are distinct heat-lovers. Gladiolus corms can be planted in April, and if set out at two-week intervals, they will provide stalks of bloom successively through summer. Be sure to provide well-drained, sunny locations for both dahlias and gladiolus.
   All lawn care tasks, from installing a new lawn by seed or sod to renovating an old one, fit perfectly into April's weather. If installing a new lawn, be sure to prepare the ground deeply and well; even the best quality sod will languish if it isn't given a root run of at least 8 inches and well-drained soil. Incorporate compost or other organic material, like composted steer manure or composted municipal biosolids. Choose grass seed adapted to Northwest maritime conditions; in general, research has shown that perennial rye grasses and fine fescues, in combination, produce a good-quality lawn. Kentucky bluegrasses do not thrive in western Washington, though some mixtures may contain a small percentage of them. The small percentages do fine, but lawns that are predominantly bluegrass will not grow well.
   Fertilize the lawn this month, using a 3-1-2 ratio fertilizer. If the lawn needs thatching, this is a good month to do it, as the lawn still has time to recover and fill in from the thatching. To determine if thatching is needed, dig out a 4-inch-square, 4 inches deep, and look at the profile where the lawn grasses meet the roots. Thatch is a dense layer of old roots and stems, and it will resemble a strawy mat. If the mat is thicker than 1/2 inch, thatching is advisable. An unthatched lawn doesn't accept water well, because the water applied can't reach the lawn roots. After thatching, the lawn may look bare and scuffed in spots. Apply grass seed, and rake the seed into the bare ground. Step on the spots gently to be sure the seed is in good contact with the ground, and keep new seeded spots well watered until they are established.
   Late in the month, move fuchsias and geraniums outside. Place in a sheltered spot, give them sun during the day, and take them indoors if nights are still in the low 40's. Neither fuchsias nor geraniums will grow well in cold night temperatures. They will just sit still in their pots and shiver. In mid-May, set them out in permanent spots.
   Many types of annual bedding and basket plants add color to nurseries now. Bring your favorites home when selections are good, but as with geraniums, keep them sheltered from cold night temperatures until around Mother's Day. If they are planted out, cover them at night for cold protection.
   While doing April tasks, take time to rest in the strengthening sun, and appreciate the rush of growth that offers energy to all gardeners.

Visit WSU's Agriculture Site on the World-Wide Web at http://www.cahe.wsu.edu.