- About Extension
- Get Involved
- Statewide Locations
December Garden Calendar
Produced by OSU Extension, each month provides reminders of key garden chores, such as fertilizing, pest control, planting, and maintenance.
Recommendations in this calendar are not necessarily applicable to all areas of Oregon. For more information, contact your local Extension office.
The Oregon State University Extension Service encourages sustainable gardening practices.
Preventive pest management is emphasized over reactive pest control. Identify and monitor problems before acting and opt for the least toxic approach that will remedy the problem. The conservation of biological control agents (predators, parasitoids) should be favored over chemical controls.
Use chemical controls only when necessary and only after thoroughly reading the pesticide label. First consider cultural, then physical and biological controls. Choose the least-toxic options (insecticidal soaps, horticultural oils, botanical insecticides, and organic and synthetic pesticides — when used judiciously).
Maintenance and Clean Up
Western Oregon: Do not walk on lawns until frost has melted.
Spread wood ashes evenly on vegetable garden. Use no more than 1.5 pounds/100 square feet/year. Don't use if the soil pH is greater than 7.0 or if potassium levels are excessive.
Protect new landscape plants from wind. Use stakes, guy wires and/or windbreaks as needed.
Yard sanitation: rake leaves, cut and remove withered stalks of perennial flowers, mulch flowerbeds, and hoe or pull winter weeds.
Turn the compost pile and protect from heavy rains, if necessary.
During heavy rains, watch for drainage problems in the yard. Tilling, ditching, and French drains are possible short-term solutions. Consider rain gardens and bioswales as a longer-term solution.
Check stored flower bulbs, fresh vegetables, and fruits for rot and fungus problems. Discard any showing signs of rot.
Tie limbs of columnar evergreens to prevent snow or ice breakage.
Central/Eastern Oregon: Water your plants every 6 to 8 weeks with a deep soaking to prevent drying out.
Western Oregon: Make sure that landscape plants in protected sites receive water regularly during the winter.
Western Oregon: Good time of year to plant trees, and landscape shrubs.
Pest Monitoring and Management
Check for rodent damage around bases of trees and large shrubs. Remove weeds to prevent rodents from using them as hiding places. Use traps and approved baits as necessary.
Avoid mounding mulching materials around the bases of trees and shrubs. The mulch might provide cover for rodents.
Monitor spruce trees for spruce aphids. Treat if present in large numbers. Read and follow pesticide label directions.
Monitor landscape plants for problems. Don't treat unless a problem is identified.
Houseplants and Indoor Gardening
Protect poinsettias from cold, place in sunlight, don't let leaves touch cold windows; fertilize with houseplant fertilizer to maintain leaf color.
Monitor houseplants for adequate water and fertilizer. Water and fertilizer requirements generally are less in winter.
Trade-name products and services are mentioned as illustrations only. This does not mean that the Oregon State University Extension Service endorses these products and services or intends to discriminate against products and services not mentioned.