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December Gardening Tips

General Gardening Tips

Chickadee at feeder

Chickadee at feeder

The migratory birds may be gone by now, but a wide assortment of species (including chickadees, finches, wrens, and Anna’s hummingbirds) don’t go south for the winter. See our blogpost here for information on encouraging overwintering birds.

For general information on backyard birds in Seattle, including the annual Seattle Christmas Bird Count, visit the Seattle Audubon Society’s website. From there, you can join a bird count group led by an experienced birder, or sign up to count birds at your own feeder!

Freeze alert! If the wind shifts to pull weather down from the north, we might get an arctic blast.  Just in case, here’s a link to our post on preparing the garden for cold weather, “It’s Going to Freeze!

Fruit Tree Gardening Tips

Pick a dry day to spray all fruit trees with copper and dormant oil. This will help to control blister mites, scale, pear psylla, moss and lichens. The copper spray also counts as one of three spray applications to control peach leaf curl.Three applications are required about three weeks apart to get full protection from peach leaf curl. For more information on dormant spraying, see our blog post here.

Prune this month or next month for air circulation, sun penetration, fruit production and to keep the trees a manageable size.

Ornamental Gardening Tips

Get help from Sky Nursery's Design Team to freshen your containers for winter.

Containers on porches or under overhangs may need to be watered.


Keep an eye on plants and containers on porches or under overhangs. Remember that rain may not reach them. Be ready with the watering can as needed.

…but not too much

Planters with saucers or flush to the ground can hold water potentially all winter, creating sogginess only a bog plant could love. There are some easy solutions to keep your plants/pots out of standing water. These include decorative pot feet, invisible pot-risers, “down under” plant stands, and deck wedges. If you’re planting a new container, consider using an “Ups-A-Daisy” false pot bottom, or drainage media in the bottom of the pot to keep air space open. Failing any of those, empty the saucers as needed.

Time to Transplant! 

Have some plants you were planning to move around? From the plants’ point of view, this month and next are prime transplanting time. It gives them the rest of the winter to acclimate to their new location and grow new roots. You can move plants any time the soil can be worked (not frozen, and not too soggy). Just check the forecast to make sure that a hard freeze isn’t expected until the plants have had a few days to settle in.

In the bottom of your hole, mix in a little granular organic starter fertilizer such as Dr. Earth Root Zone or EB Stone Sure Start to get your plants over any transplant shock. Don’t use a liquid or water-soluble fertilizer at this time. Be sure to water your plants in well even if it’s forecast to rain.

hellebore in bloom

Helleborus, or Christmas rose

Plant for Winter Interest

Winter interest trees and shrubs such as camellias and viburnum, perennials such as hellebores and heucheras, and cold-season color spots can all be planted this month. Follow the same guidelines as for transplanting.

Living Christmas Trees

Consider getting a tree that you can plant in your yard or in a large outdoor container as a permanent memento of the holiday season! You can keep a potted conifer indoors for about 5-7 days. Here’s our Living Christmas Tree information sheet for full details. 

magenta florist cyclamen

Florist cyclamen

Tender Container Plants

Florist Cyclamen, ‘Frosty Fern’ Selaginella, and ‘Wilma Goldcrest’ Cypresses are gorgeous, but they are not freeze-hardy. So, instead of taking them out of the pot to plant, try planting them pot and all. Then if a freeze threatens, just yank the pots and move them someplace protected until the weather moderates again.

Indoor Gardening Tips

Moth Orchid and Tillandsia

Moth orchid and tillandsia

It’s winter now (despite what the calendar says about 12/21 being the “official” beginning), so remember the standard winter tip: the short days and low light levels mean your indoor plants slow their growth. Unless you are using grow lights, cut back on watering and stop feeding. 

On the other hand, central heating can dry the air. Sensitive plants such as orchids may benefit from a humidity tray—just a water-filled tray with pebbles (or pot feet) so the plant is not sitting in water, but still benefits from the evaporation. For more details on winter indoor plant care, click here.

Sky has an abundant selection of poinsettias, zygo cactus (AKA Christmas or Thanksgiving cactus), Norfolk pine, and amaryllis for your holiday enjoyment—and as always, a full line of regular foliage and flowering plants as well.

Lawn Care Tips

If you fertilized last month, December lawn care is easy: leave your lawn alone! If you didn’t fertilize, stop reading and do it now. If we have a windstorm you might need to do some raking and clean up, but otherwise you have nothing to do except let your lawn alone until the next feeding around Valentine’s Day.

Water Gardening Tips

Keep dead leaves skimmed (or net your pond). Pay attention to skimmer boxes and clean them often.

Don’t feed fish in winter.

Make sure you have an air pump or some other deicing going if freezing temperatures arrive.  Never smash a hole in ice as it can hurt your fish. An airstone is a great way to keep an area clear of ice and keep your water well aerated, especially if you have to turn waterfalls off.

Consider installing a water return line (a line that bypasses waterfalls but keeps water circulating through biofilters) if you will be away from your pond for long periods during the winter.

Winterize fountains if you didn’t last month: remove pumps and protect concrete from freezing. Sky carries fountain covers in different sizes.