It is important to water your containerized plants before and during sub-zero temperatures when the air is dry and the wind is blowing.
Please see our Winter Prep page for detailed information about protecting your garden from cold damage. For most of us, January is mostly about staying warm and planning ahead, but there are little things you can be doing to protect your plants, and any weeding you can do now means a lot less work later on.
Did you have a cut Christmas tree this year? Don't leave it in the house too long, it becomes a fire hazard. Living (potted) Christmas trees should not be in the house longer than one week. In other words, by January the tree really needs to be back outside. Please see our brochure on living trees for details to ensure your tree thrives.
Many species of birds overwinter in the Portland area, including some hummingbirds. Continuing to provide seed, suet, and nectar helps to keep populations healthy, and back door bird-watching is fun. When the temperature drops well below freezing, regularly placing plastic containers of water outside provides drinking water for them.
January is not an especially good season for planting new plants or disturbing the soil, particularly if your soil is primarily clay like most of us in Portland. It is likely that your soil is water-logged or frozen. Disturbing clay-based soil in these conditions often compacts the soil, making it harder for the plants in the long run. You probably won't kill a hardy plant if you plant it now, but it is better to wait a while.
Any bulbs that were set aside in the autumn for forcing indoors can be started now if they have had two to three months of chilling. Tulips, Narcissus, and hyacinths are all good plants for this. Plant them in fresh potting soil and grow them indoors in bright windows, keeping the soil evenly moist. They will be blooming soon, and you can enjoy a little 'spring color' indoors before spring itself arrives. Once the bulbs are done blooming and spring arrives plant the forced bulbs in the earth, sometimes they will naturalize and come back the following year.
Most plants are of course dormant now, but there are a few things that bloom in January with wonderful flowers. Witchhazel (Hamamelis spp.), some heathers (Erica spp.), winter jasmine (Jasminum nudiflorum), Camellia sasanqua, and Garrya elliptica
all bloom this early, and winter daphne (Daphne odora) and wintersweet (Chimonanthus spp.) may be starting. It's quite pleasant to have colorful shrubs in the middle of winter, but here's the best part: many of these flowers smell amazing. Some of the best scents in the world are to be found in the winter garden.
Little care needs to be given to permanent plantings in the ground, except possibly some protection from hard freezes for broadleaved evergreens or half-hardy plants. See the care sheet hyperlinked above for details.
Many ornamental deciduous trees handle pruning best in winter, so if any is necessary this might be an acceptable time. It is still a bit early to be pruning most fruit trees. Most shrubs should be pruned after blooming, so winter pruning is usually not recommended. The exception is any branches that you need to completely remove to renovate the plant. Only do this for a good reason, such as the branches are damaged or unacceptably placed. Most conifers do best with little or no pruning, but any moderate to major cuts you need to make should be done in late autumn to midwinter to minimize sap loss. Minor shearing of hedge or topiary plants can be done now, but they will look better if you wait until spring when they will flush back out quickly. Feel free to check with us as to proper timing for your particular plants. If you are pruning branches off of early flowering plants such as cherry or forsythia, understand that you will have fewer blossoms on your plant in spring. The good news is that you can take some of the smaller cut branches inside and put them in a vase; the blooms will open up in your home for some early color to enjoy.
Dormant spraying can be done in January if you can find a dry day, though a lot of gardeners wait until February. Dormant spraying is defined as spraying your deciduous shrubs and trees that are disease or insect prone to help prevent infections later in the growing season. Dormant sprays will damage leaves, so that is why we use them when the plant is dormant and leafless. Examples include copper sulfate, lime-sulfur (both for fungus), and horticultural paraffinic oils (for certain insects). Do not confuse this with neem oil. Check with us or a reliable source for which spray to use for the problems that infect your plants. Fruit trees, roses, and lilacs are examples of plants that benefit from dormant spraying. It is also a good idea to make sure there are no leaves still clinging to these plants, and to rake and remove leaves before spraying if you did not in autumn.
What snow or ice we get often comes in January, and upright conifers such as arborvitae and cypress can take damage and lose branches in harsh weather. It is a good idea to wrap such plants with twine for a few weeks, binding the branches together so they can support each other. This can minimize any damage to the plants.
It is too early for starting seeds for a vegetable garden, but our new stock of seeds arrives now and our selection is at its best. Your existing kale and other winter greens growing outside or in a cold frame need to be protected from severe dips in temperature with frost blanket. If we are expecting a severe storm, you might just consider harvesting the rest of your greens and eat fresh salads while you are snowed in.
There is little to be done for lawn in the heart of winter. Wait for fairer weather for any seeding or renovation. Moss can be a problem throughout the winter, and applications of moss control products can help to slow the spread. Be sure that the product you select is labeled for lawns, as some moss control products can hurt lawn and other plants. Also, heavy rains following application will simply wash the product away, so time your spray appropriately.
Even though your indoor plants are heated and not fully dormant, they often slow in growth rate and thin out in winter because of the lack of natural light. Grow lights can help of course, but most houseplants don't require them. Tropical plants that prefer direct sun such as Gardenia, Citrus, and Bougainvillea get quite sparse in winter if they are simply in an average living room. See our guides for overwintering these plants in the houseplant section of our brochures page.
In general, do not fertilize in winter and be careful to water moderately. This means allow plants to partly or even mostly dry out, but water before the soil is fully dry. It is more common for people to overwater plants in winter than to let them get too dry. Repotting should be put off until spring, especially for dry-loving plants such as cacti or succulents.
Often people acquire winter blooming plants over the holidays, and some of these can turn into permanent houseplants. Christmas cacti can live for many years for most gardeners, and are not too hard to rebloom in future years. Despite the fact that they are cacti, they cannot handle extended periods of dry soil and should be moderately watered like most houseplants. Poinsettias often fail after serving their purpose for décor, but if you have treated yours well it may be able to continue to thrive and rebloom next year. Both poinsettias and Christmas cacti require a long night cycle in autumn to early winter in order to rebloom, so remember that for your future plans for them. Note that indoor lighting in your living room or bedroom can disrupt this cycle. Paperwhites should generally be discarded after flowering.
Portland Nursery has its largest sale on houseplants in January, so check with us for details regarding the dates and discounts available.
Visit individual month pages for gardening ideas. Pages are regularly updated with projects for that month.