Autumn is one of the most beautiful times of year in the Northwest garden. Summer is a thing of the past and winter will be here before we know it. Fall color spreads through the trees, shrubs and deciduous vines, illuminating rain-filled skies with the light of brightly colored foliage. Other cities in other parts of the country turn brown with the onset of colder weather. Our gardens take on the lush, deep color tones of a temperate, maritime climate.
Even the lawns in Southwest Washington turn a deeper, more richly colored green in gratitude for the autumn rains. As long as we have days of moderately warm air, warm soil and warm rain, turf grass will continue to grow. Warm-season lawns need to be mowed less often in the fall. Fescue in the mix continues to grow enough to need a couple more mowings. Wherever you live, you should only plant grass with a reliable record of performance in your area.
In the Pacific Northwest, blends of perennial ryegrass, fescue and
bent or Kentucky bluegrass are the lawns of choice. Although tall fescue is available, it has trouble competing with the other grasses during wet, chilly winters. Depending on a lawn's condition, you may want to aerate now to help make the soil less compact and encourage root growth. The best aerators remove plugs of earth by piercing the soil and pulling out the plug, somewhat like coring an apple.
After aerating, reseed the entire lawn area and add lime if necessary. A soil sample kit will help you decide what your soil lacks and what it needs to be in peak condition. This is the most important time of year to add a slow release fertilizer. For the best lawn, choose an organic fertilizer that feeds the soil with a mix of nitrogen, phosphorus, potassium and iron. The rate and frequency of fertilizing depends on soil and grass types, as well as manufacturer instructions.
Prepare for winter
The first step in committing the rest of your garden to winter preparation is to remove any dead or dying annuals, as well as spent perennial plant material. Most tender bedding plants will become leggy and past flowering by the end of the month. They will never look any better than they do right now, so don't hesitate to add them to the compost heap. Remember that we never add diseased or insect-infested foliage to a compost pile.
If you've already planted out cool-season pansies and kale, keep them neat and tidy by removing spent flower heads and withered, weather-beaten foliage. Cut pansies back to within a couple of inches of the ground and they will very likely give you another flush of bloom before real winter sets in. If you have dahlias planted out in the garden, the time to cut them back to the ground is after the first killing frost. The stalks and foliage will turn dark brown, almost black and should be cut back close to the tuber.
Trim up any overgrown hedges at this time and make sure that all hedges are clipped so that the sides taper upward, with the widest part of the hedge at the base and the thinnest width at the top. This way, if snow should find your garden, it will not accumulate on top in a way that splits the hedge open in the middle but will fall more readily off the sides of the hedge. If you have a hedge of yew or any other needled evergreen, tie in or remove branches that look like they might catch and hold quantities of snow.
Take the time to protect any half-hardy or tender plants before cold weather comes to the garden. It may be too late to save these plants if you wait until after the garden is hit by frost. If you are leaving dahlias in the ground, mulch them with compost, bark or leaves to create a blanket of protection around the root system. Most roses will benefit from an application of straw and mulch, mounded 5 or 6 inches deep at the base of the rose canes.
The pace of garden chores has begun to slow down, so think ahead to spring. Have the lawn mower serviced and clean up garden tools. After losing a couple of lovely Japanese maples to falling clumps of frozen snow, I always remove any pots and planters from the fall line of the roof of the house. Bring tender potted plants inside or at least to a protected area for the winter. Whatever you do, take a moment to delight in the splendor of autumn all around you in the garden.