March in the garden
by Mary S. Robson, Area Extension Agent, WSU Cooperative Extension
Perhaps this month is called "March" because we have to keep marching to the garden's inspired and active new spring beat! Days lengthen, early bulbs flower, and welcome sun returns. March, like October, is one of the busiest months in the maritime Northwest garden.
Transplant trees and shrubs. March is the last good month for this until about October 1. Plants from containers can be installed year-round, but moving an established plant has to happen when the roots are still relatively dormant and soils haven't dried out. Choose and plant trees and shrubs from nurseries. Look at spring-blooming shrubs in containers to find your favorites. Plant summer and fall-blooming perennials. Sow hardy annual seeds--sweet peas, bachelor buttons, California poppies, and red Shirley poppies.
Complete garden clean-up. Raking and disposing of all old fallen leaves and fruit now will reduce reservoirs of disease organisms. Weed. Weed and weed. Winter weeds like little bittercress are going to seed now and spring weeds are popping up. Pull them while they are young to avoid months of troubles later. Weed seeds stay viable for years, so the old saying, "One year's seeds, seven years' weeds," isn't far off.
Prune any diseased or damaged tree and shrub limbs; shape the plants. Thin overcrowded branches to improve air circulation, which will also help plants stay healthy by reducing fungal infections. Spring-blooming shrubs such as forsythia, spirea, and rhododendron are pruned immediately after blooming. They form buds for next year's flower show in late summer, so pruning too late removes next year's bloom. Prune now!
Trim and feed roses. Treat with a fungicide registered for use on roses directly after pruning, especially if you've had disease problems with black-spot or rust. The disease organisms can live over on the canes, even after affected foliage is gone. Supply fertilizer to roses when leaves begin to expand. Roses bloom on newly-produced wood and need good levels of nutrients to produce healthy and abundant flowers.
If your roses are climbing types, remember that they produce blooming laterals–new wood–off established older woody canes. So don't chop a climber to the ground. Leave a framework of strong canes and tie those up.
Check for slugs around spring bulbs and emerging lilies. These hungry mollusks will climb stems and hollow out the daffodil blooms, or chew through a tulip stem. Hand-pick slugs or use baits carefully. Follow directions and put baits into covered containers that can't be reached by children or pets. Spring-blooming bulbs come back better year after year if they are fertilized with a 5-10-10 ratio material broadcast at the rate of three to five pounds per square feet. Do this when bulbs are just up, before they bloom.
Many established landscape plants grow well without supplemental fertilizers. However, if the plant has off-color leaves (yellowing) or is putting out very little new growth, it may benefit from fertilizing as it begins to grow. Try a 5-10-10 fertilizer spread under the plants. Check the fertilizer package or bag for the exact rate of application and don't over-apply. All landscape plants benefit from compost applications in the spring; either spread about an inch of your own compost, or use a commercial compost such as Groco or Cedar Grove Compost.
Fuchsias and geraniums start growth. Remove them from winter storage. Trim off dead or damaged branches, repot in fresh potting soil, and water well. Get these plants into light, as bright as possible, but give them protection from late frosts. Plant tuberous begonias indoors. A source of bottom heat helps them sprout (try putting the planted tubers on top of the refrigerator.) Stored dahlias and gladiolus can be planted outside after mid-month.
When vegetable garden soils are dry enough to work, plant peas, lettuce seedlings, broccoli, and cabbage transplants. Toward the end of March, start peppers and tomatoes indoors. Allow six weeks before you set them outdoors. If warm-weather crops are started indoors too early, the plants get leggy and weakened from lack of light.
Plant blueberries, raspberries, and strawberries now. Blueberries can take damp, even boggy, areas if they have good sunlight. All other fruit crops require sunny, well-drained non-boggy planting areas.
Lawns--remember lawns--must be mowed before they get too long. Sharpen mower blades. De-thatching and over-seeding can be done now. Dig out dandelions and other perennial weeds before over-seeding, or spot-treat the weeds with an herbicide, following directions exactly. Lawn renovation now will result in a healthier, better-looking lawn through the summer.
Take time to enjoy the longer days; sit in the garden with a morning cup of coffee or tea and savor spring's arrival. Then get busy!
Visit WSU's Agriculture site on the World-Wide Web at http://www.cahe.wsu.edu.