OSU Gardening Calendar

April

Planning

Write in your garden journal throughout the growing season.
Prepare garden soil for spring planting. Incorporate generous amounts of organic materials and other amendments, using the results of a soil analysis as a guide.
Prepare raised beds in areas where cold soils and poor drainage are a continuing problem. Incorporate generous amounts (at least 2") of organic materials.
Use a soil thermometer to help you know when to plant vegetables. When the soil is consistently above 60°F, some warm season vegetables (beans, sweet corn) can be planted.

Maintenance and Clean Up

Allow foliage of spring-flowering bulbs to brown and die down before removing.
Apply commercial fertilizers, manure, or compost to cane, bush (gooseberries, currants, and blueberries), and trailing berries.
Place compost or well decomposed manure around perennial vegetables, such as asparagus and rhubarb.
Cut back ornamental grasses to a few inches above the ground, in early spring.
Cover transplants to protect against late spring frosts.
Optimum time to fertilize lawns. Apply 1 lb. nitrogen per 1,000 sq.ft. of lawn. Reduce risks of run-off into local waterways by not fertilizing just prior to rain, and not over-irrigating so that water runs off of lawn and onto sidewalk or street.
Western Oregon: Optimum time of year to dethatch and renovate lawns. If moss was a problem, scratch surface prior to seeding with perennial ryegrass.
Western Oregon: Prune and shape or thin spring-blooming shrubs and trees after blossoms fade.
Central/Eastern Oregon: If snow mold was a problem, scratch surface. If turf damage is severe, seed with Kentucky bluegrass.
Central Oregon and higher elevations of Eastern Oregon: Prune your deciduous trees and shrubs, using proper pruning techniques.

Planting/Propagation

Plant gladioli, hardy transplants of alyssum, phlox, and marigolds, if weather and soil conditions permit.
It's a great time to start a vegetable garden. Among the vegetables you can plant, consider:
- Oregon coast: beets, cabbage, carrots, cauliflower, celery, chard, slicing cucumbers, endive, leeks, lettuce, onion sets, peas, and potatoes.
- Western valleys, Portland, Roseburg, Medford: broccoli, Brussels sprouts, cabbage, carrots, cauliflower, chard, chives, endive, leeks, lettuce, peas, radishes, rhubarb, rutabagas, spinach, and turnips.
- Central Oregon and higher elevations of eastern Oregon (late April): peas, radishes, lettuce, spinach, and turnips.
- Columbia and Snake River valleys, Ontario: snap and lima beans, beets, broccoli, Brussels sprouts, cabbage, carrots, cauliflower, chard, chives, sweet corn, slicing and pickling cucumbers, kohlrabi, leeks, lettuce, onion sets, parsnips, peas, potatoes, pumpkins, radishes, rhubarb, rutabagas, summer and winter squash, and turnips.

Pest Monitoring and Management

Clean up hiding places for slugs, sowbugs and millipedes. Least toxic management options for slugs include barriers and traps. Baits are also available for slug control; iron phosphate baits are safe to use around pets. Read and follow all label directions prior to using baits or any other chemical control.
Monitor strawberries for spittlebugs and aphids; if present; wash off with water or use insecticidal soap as a contact spray. Follow label directions.
If necessary, spray apples and pears when buds appear for scab. See EC 631, Controlling Diseases and Insects in Home Orchards.
Cut and remove weeds near the garden to remove potential sources of plant disease.
Use floating row covers to keep insects such as beet leaf miners, cabbage maggot adult flies, and carrot rust flies away from susceptible crops.
Help prevent damping off of seedlings by providing adequate ventilation.
Southwest Oregon: Place pheromone traps in apple or pear trees in late April to monitor codling moth activity.
Western Oregon: Manage weeds while they are small and actively growing with light cultivation or herbicides. Once the weed has gone to bud, herbicides are less effective.
Western Oregon: Spray stone fruits, such as cherries, plums, peaches, and apricots for brown rot blossom blight, if necessary.

Download a PDF of the April Calendar for easy printing.

Updated September 10, 2009.

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