What to do in the Garden in December

These are reminders of key garden chores, such as fertilizing,  planting, maintenance, and pest control for this month. These are for reference only and no one need feel like they should do everything on the list even if they do all apply to your yard.  Gardening should be fun!  Just do what you can and pick the things that are most important to you first.

Maintenance and Clean Up

•   Protect new landscape plants from wind. Use stakes, guy wires (with some flexibility) and/or windbreaks as needed.  Plan to loosen wires in spring to allow for growth and some movement.  The swaying of the trunk encourages it to grow stronger. Trees should not be tied in place longer than one growing season, in most cases. See this article for more.

Stake 1/3 up the tree if necessary.  Allow some flexibility.
Photo from University of Minnesota.

•   Rake leaves and use to mulch flowerbeds or make a compost pile if you have space.  See this list of OSU extension articles for more.  If leaves have significant disease problems, as in some rose, tomato, or fruit tree leaves, for example,  it may be best to hot compost or place them in yard debris bins. See this article about hot compost
•   If you have a compost pile already, turn the pile and protect from heavy rains to protect nutrients from being washed away.
•   You can also start getting a new bed ready for spring planting by simply piling leaves on very thickly (10-20") to kill grass.   This head start plus keeping plenty of mulch around new plantings will improve the soil and give your plants a great spot to grow without competition or herbicides.  

The dark leaves have just been brought in to start a new bed that will save us from mowing
 around the trees and add habitat value. The lighter leaves were raked up from those trees earlier and used to mulch existing beds- preventing weeds, improving soil, protecting tender plants, conserving moisture come summer time, and saving us time doing too much raking and weeding.  Yay leaves!

•   Hoe or pull winter weeds.  If you have a patch with many weeds, you may save time by covering them with cardboard and then mulching over the cardboard.  Just hoe any survivors.  There won't be many.

Cardboard weed suppression.  Cover with mulch of your choice.

•   Spread wood ashes evenly on the vegetable garden. Use no more than 1.5 lb/100 sq ft/year. Don't use if the soil pH is greater than 7.0 or if potassium levels are excessive.  

•   During heavy rains, watch for drainage problems in the yard. Ditching and French drains are possible short-term solutions. Consider rain gardens and bioswales as a longer-term solution and a fun excuse to do some landscaping.  See this download of a booklet from the City of Portland with photographs and rain garden design, construction, and planting information.  Don't forget to click on the download. 

Three year old rain garden.  It has river rock (3" drainage rock) mulching the bottom of the ponding area, but the native strawberry has spread with such exuberance that it is hard to see.  This ponding area absorbs all of the rain from the small barn so quickly that standing water is never visible, even during a downpour.  Plants in and around the rain garden include native shrubs and rushes, flowering perennials, grasses, and fruit trees.

•   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.

•   If possible, avoid walking on frosty lawns until frost has melted.

•   If you have landscape plants in protected sites that don’t receive rain, remember to water them occasionally during the winter. 

Planting/Propagation

•   Good time of year to plant trees and landscape shrubs.  See this article for how to's and information about a helpful new app for tablets. 

Dig the hole twice as wide, but no deeper than the pot.
A garbage bag  under the loose soil makes clean up easy.

•   Check that your seeds are sealed up tightly somewhere cool or cold.  A small packet of silica gel or dry milk can help absorb any residual moisture.

Pest Monitoring and Management

•   Monitor landscape plants for problems. Don't treat unless a problem is identified.

•   Check for rodent damage around bases of trees and large shrubs. Remove weeds to prevent rodents from using them as hiding places.

•   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 only if present in large numbers. Read and follow pesticide label directions. 

•   Identify problems before acting, and opt for the least toxic approach. Cultural, physical and biological controls are the cornerstones of a sustainable pest management program. Use chemical controls only after you identify a pest problem and carefully read the pesticide label. Least-toxic choices are insecticidal soaps, horticultural oils, botanical insecticides and organic and synthetic pesticides. These recommendations might not apply to all areas of Oregon. For more information, contact MasterGardeners by phone or email on this website. 

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.

Please comment and ask questions!  We'd love to hear from you!