Why December Gardening Matters (Even When It’s Cold)

pexels-myfoodie-3094075

By Marie Kurka-Brown 

For me, December gardening generally meant finding a good British Whodunnit Movie to watch while waiting for a colorful seed catalog to magically appear in my mailbox. 

Today, as a WSU Extension Master Gardener, I've learned the importance of both Fall Clean Up and December Gardening. 

And everything that I do in December will save me next spring. Including watching just one British Whodunnit.

Mulch

There was a time when I didn’t mulch or even think about amending my soil. Now after mulching these last few years, I can actually see the difference.

Mulching provides multiple advantages for gardens. It retains soil moisture, suppresses weeds and regulates soil temperature, and can even help prevent erosion. Organic mulches decompose over time enriching the soil with nutrients used this last season. 

Inorganic mulches primarily offer long-lasting weed control and moisture retention.

Keep garden tools clean  
I’ve learned to keep my garden tools clean and ready to use because Mother Nature switches up my timetables occasionally. Cleaning tools with a mild soap generally works and using alcohol on my pruning shears between plants is now automatic for me. I’m slowing down the spread of disease between plants.

Winterize outdoor water features

My Koi Pond was finished this past summer, and I now have something new to think about and that’s winterizing outdoor water features. Things that I hadn’t thought about before like the freeze-thaw cycle, ensuring my pumps, pipes and water found structure last longer and are ready when Spring arrives.

Maintain good airflow in your plants

Maintaining good airflow in your plants is critical to their health. Deciduous trees actually heal pruning cuts faster when pruned in late winter, than other times of the year. The cold slows sap flow, reducing disease entry. December is also a good time to plant bare-root roses, trees, and shrubs.

Force bulbs to bloom for indoor color

December is an excellent time to force bulbs to bloom and add “winter color” indoors. Most spring bulbs need a chilling period to break dormancy before they can bloom. After chilling, bulbs require 2-6 weeks in warm, bright conditions to grow and flower.

Spring catalogs

For me the only thing better than a British Whodunnit is Spring catalogs. I can easily fall in love with that new plant that is either new, or I’ve never seen it before. (Who special is that and I’m not competitive ... I don’t have to have it first in my yard! Not really)

Continue to feed the birds

Winter is for the birds – if you start feeding them, please continue feeding them. Recent research shows that climate change is already reshaping the distribution, abundance, and timing of many Pacific Northwest bird species, with notable effects visible in winter (December) conditions. 

As nature adjusts to a changing climate, gardeners have an opportunity to do the same. A little effort now pays big dividends in spring. Keep this December garden checklist handy and tackle one task each weekend. 

Plant vegetables in December

When March arrives, you'll be glad your garden is already a step ahead. And if the weather allows, December is also an excellent time to plant broccoli, kale, onions, and winter flowers, bringing a touch of life and color to the garden even in winter's quiet season.

For more information on gardening, please follow the link to About | King County | Washington State University

Marie Kurka-Brown
WSU Extension Master Gardener (class of 2020)
Master Gardener Foundation of King County (elected 2025)