Wednesday, December 5, 2012

Plant in the Fall for good growth the next year

Written November 4, 2012, published mid November 2012

As an ecologist who likes to garden, I’ve worked and reworked the design and plants in my garden for years, starting with a traditional older coastal garden with lawns, rhododendrons, camellias and roses. I tried perennials and cottage-style beds, then a more Mediterranean-style garden with sages, lavenders, rosemary, bulbs, rockroses, and no summer irrigation.  This led me to focus on soil health, lower impact gardening, and to growing more native plants. I always had a few in my garden, especially evergreen huckleberry and sword fern. Now I have many more, and the result is a hardy, tough garden, full of flowers, bees, butterflies and birds, that needs little to no summer water. 

Common Camas, Camassia leichtlinii, grows 30-40 inches tall, with light blue to dark blue flowers, and is very attractive to native bumblebees and early butterflies. Camas grows in spring wet /summer dry soils, in full sun. Photo by Kathleen Sayce. 

Our wet winters and dry summers aren’t common around the world. Places with some rain all year round, or with dry winters and summer rainfall, cover most of the planet’s landmass. Our local area is considered a cool Mediterranean-type gardening zone. In Mediterranean-type climates, the driest time of year coincides with the most sun and heat. Our summer and early fall weather tends to be quite dry. Small patches of this climate occur all over the world at moderate latitudes, yet the total area does not cover more than ten percent of the planet.  

Pacific wax myrtle, Myrica californica, is an evergreen shrub to small tree. It grows in full sun to part shade, and can tolerate both damp and dry sites. Birds like its waxy berries. It makes good hedges for screening, to 10-15 feet tall, and mixes well with shore pine and salal in hedgerows. Photo by Kathleen Sayce

How our native plants cope

Native plants in the maritime Pacific Northwest compensate for dry summers by timing bud-break, leaf-out, flowering and seed production to seasonal water. These plants also engage with soil fungi with roots; this improves access to nutrients and water. Native plants often have two distinct growing periods, spring and fall, and may go partially dormant in late summer when water stress is the greatest. Many flower in spring, set seed by early to mid summer, and wait out the dry season partially dormant; then they put out new roots in fall. They are ready to grow if rain falls during the dry season, but survive if the weather stays dry.  

Kinnikinnick, Arctostaphylos uva-ursi, is a low growing evergreen groundcover with pink flowers and red berries. It grows in full sun to part shade, in damp to dry sites, and mixes well with heathers and salal. Photo by Kathleen Sayce

Plant in the fall

The best time to plant is in autumn––after the start of rain, usually October or November. As soils cool down and rain starts, plants’ roots begin to grow. They grow new roots when soils are moist and temperatures are at or above 40 F. In mild winters, this can be almost all winter long.  The bigger the root system by next spring, the more that plant will be able to grow that summer. Fall planting decreases the amount of water needed the next summer because these root systems are bigger than if planted in spring, just before the dry season starts. Reduced watering the next summer by planting the prior fall sounds pretty good. Less watering during the dry season is also very efficient. 

Salal, Gaultheria shallon, is an evergreen shrub that can be kept low or allowed to grow more than six feet tall. It has early pink flowers and edible dark blue berries, and grows in damp to dry soils, full sun to part shade, and mixes well with other shrubs and groundcovers for hedges and woodland plantings. Photo by Kathleen Sayce.

Food for native animals

There is an important ecological reason to use native plants: to support native animals. Insects, birds, small mammals, and the animals that feed on them, are ultimately dependent on native foods. Yes, there are introduced plants that can be eaten by generalist native animals, particularly deer. By and large, most native animals key in on a few native species. If you want butterflies, bees and other pollinators, birds, amphibians and mammals to hang around your yard, put in native plants. Large areas planted to introduced species are ecological deserts for native animals. There’s nothing for them to eat. 

There’s an excellent book on this subject by Douglas Tallamy, Bringing Nature Home, which contains a wealth of details about the complexity of native plant communities, the animals they are food for, and the choices we have to encourage, or discourage, native ecology in our own yards. He writes about Delaware, but the principles are the same here in the Pacific Northwest. 

If you dislike hauling hoses around, and prefer a garden that can take care of itself in droughts, torrential rains, and snow, then select native plants over introduced plants. There are hundreds of species, including trees, shrubs, perennials and bulbs. The result is a garden that is more attractive to native animals, including butterflies, bees and birds, which needs little to no summer water, and survives our wet cold winters in good condition.  Don’t forget the time of year to put in those native plants––in fall. 

Indian rhubarb, Darmera peltata, flowers in the spring, then the leaves come out afterwards. It prefers soils that are wet to damp year round, in part sun to shade. Photo by Kathleen Sayce

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