Question: Can you give us any information on plants that will do well in our coastal climate and also give us spectacular fall color?
Answer: Our mild climate allows us to grow an enormous diversity of woody ornamentals- some of which are prized for their spectacular fall color. Here are some of my favorites for great fall color with an emphasis on red foliage. Euonymous alatus compacta, the burning bush, is the one you see adjacent to the freeway in Olympia with vibrant red foliage. Other choices include viburnums, Japanese maples, barberries, Cotoneaster and Enkianthus. Those wanting more than just great fall color might find blueberries to be the perfect choice. Trees with red foliage include Amur maple, Chinese dogwood, sweet gum and Japanese hornbeam.
These plants provide brilliant gold foliage: witch hazels, Kerria, magnolias, lilacs and some deciduous cultivars of Photinia. Trees with gold foliage include: sugar maples, Norway maples, tulip trees and Ginkgo biloba, the maidenhair tree.
Any of these choices will help to brighten your landscape with a colorful display of fall foliage. The cooler temperatures and ample soil moisture make this time of year ideal for planting woody ornamentals. Most local nurseries and retail garden centers carry the more common plants listed above and can usually order the unusual varieties.
Question: Is there a weed killer we can apply to prevent weeds from growing over winter in our landscape beds?
Answer: Unfortunately, many weed species are completely resistant to our cold wet winters. Winter annuals like groundsel, shotweed and common chickweed thrive under low light intensity and cold temperatures. Even tough rooted perennials like dandelion, spotted cat's ear and quackgrass are not phased by freezing temperatures.
Fortunately, there is a pre-emergent herbicide called Casoron which can be used in home landscapes around most established trees and shrubs. It is a granular material that when sprinkled on the soil, forms a vapor which prevents both winter and summer annuals from germinating. Now is an excellent time to apply Casoron as it needs both cool temperatures and moisture to be effective.
While Casoron is a simple and effective herbicide for home gardeners to use, it can also cause problems when used inappropriately. Casoron will effectively kill most plants that have an herbaceous or non-woody root system. This includes all perennials as well as spring flowering bulbs like daffodils and tulips. If you do choose to use Casoron, don't plan on trying to grow herbaceous plant material in treated areas for at least a full year after application.
While Casoron is effective in preventing weed germination, it has limited value in killing off established perennial weeds like quackgrass and dandelions. Translocated herbicides like 2, 4-D will eliminate dandelions while glyphosate (Round-Up) formulations will effectively kill most grass weeds when used according to labeled directions.
Question: What is the best way to tell when a houseplant should be watered?
Answer: The best way is to feel the soil mix with your finger tip. If it is cool, and barely moist to the touch, the plant is considered moderately moist. If the soil mix is slightly moist, or questionable, it is best to wait another day or two and retest before watering. Another effective method to determine when to water is to use the weight of the container. A dry container and soil mix will be lightweight compared to one that has just been watered.
Most plants do well when the soil mix is "moderately moist." After watering thoroughly, allow the soil mix to dry to a slightly moist condition before watering again. Completely saturate the soil mix with water to fill all of the pore spaces. Pour enough water into the pot that it drains out through the drainage hole. This method is beneficial in leaching out excess fertilizer salts in the soil, which build up over time. It also exchanges the air in the soil mix. Do not allow drainage water to seep back into the soil mix; empty the excess water from the saucer as soon as the container drains completely.
EDITOR'S NOTE: For answers to local gardening questions, contact Master Gardener Rachel Gana at 642-8723 or e-mail her at: firstname.lastname@example.org.