WSU Extension Snohomish County Master Gardeners
SCMG Education Outreach
December GARDEN TIPS AND TASKS
SCMG Education Outreach
December GARDEN TIPS AND TASKS
SPOTLIGHTS IN THIS ISSUE
PEST MONITORING AND MANAGEMENT - Cankers, tent caterpillars, slug eggs.
GENERAL OVERALL MAINTENANCE - Monitor moisture in protected areas, gift ideas, Winter Speaker Series.
EDIBLES - Planning for next year’s garden: vegetable seed-starting, choosing fruit trees and small fruits.
FLOWERS AND FOLIAGE - Winter injury protection, pruning, winter garden design, holiday indoor plants, propagation by cuttings.
LAWNS - Final mowing if needed, rake leaves or mulch-mow, avoid walking on lawn.
PLANT OF THE MONTH - Mahonia cultivars, Oregon grape.
PEST MONITORING AND MANAGEMENT - Cankers, tent caterpillars, slug eggs.
GENERAL OVERALL MAINTENANCE - Monitor moisture in protected areas, gift ideas, Winter Speaker Series.
EDIBLES - Planning for next year’s garden: vegetable seed-starting, choosing fruit trees and small fruits.
FLOWERS AND FOLIAGE - Winter injury protection, pruning, winter garden design, holiday indoor plants, propagation by cuttings.
LAWNS - Final mowing if needed, rake leaves or mulch-mow, avoid walking on lawn.
PLANT OF THE MONTH - Mahonia cultivars, Oregon grape.
PEST MONITORING AND MANAGEMENT
![Picture](/uploads/1/2/3/8/12386481/screen-shot-2023-11-23-at-1-03-31-pm_orig.png)
Bare branches afford you the opportunity to look for problems that might have been hidden by foliage.
Watch for…dead patches or sunken cracked areas on the bark of plants.
Watch for…dead patches or sunken cracked areas on the bark of plants.
- These may be cankers, dead sections of bark on a tree or shrub. They may have started as lesions caused by an injury to the plant, allowing a bacterial or fungal pathogen to enter. Canker diseases frequently weaken and can even kill plants.
- Provide proper culture to increase plant vigor and help in recovery.
- Avoid bark wounds.
- Prune off branches with cankers, cutting several inches back from the canker.
- Wait for a dry day.
- Sanitize tools between cuts.
- Monitor the tree next spring.
- Washington State University (WSU) website Hortsense; Maple: Nectria canker.
- WSU website Hortsense; Canker: Boxwood.
- United States Department of Agriculture (USDA) publication; Canker and Rust Diseases.
- These may appear as bands around small twigs, near the tip of a twig, at the crotch formed where the twig joins a larger branch, or as flat masses on the trunk.
- Tent caterpillar egg masses may be protected by this styrofoam-like coating (spumaline).
- If possible, pick or scrape the mass away and destroy. Be sure to keep an eye on that plant next spring and remove any tents you find.
- WSU Tree Fruit publication; Tent Caterpillars.
- Photo credit: Tent caterpillar egg mass on twig; Hortense; A. L. Antonelli
- Possible evidence of slug presence.
- Trap or hand-pick slugs and destroy.
- Replenish slug bait, if used, and protect from rains.
- Collect and dispose of eggs.
- WSU Snohomish County Master Gardener Foundation publication; Tips and Tasks; March.
- Accurately identify the pest or problem. For help you can contact the Master Gardener hotline at 425-357-6010 or send an e-mail with a photo to: [email protected]
- The Snohomish County WSU Master Gardener Office Clinic is open from 11:00 AM to 3:00 PM Monday through Thursday. Walk-ins are welcome! The clinic is located in the Administration Building at Willis D. Tucker Park, 6705 Puget Park Drive, Snohomish, WA 98296.
- If you want to do the research on your own, here’s a helpful website:
- WSU website; Hortsense.
- If you want to do the research on your own, here’s a helpful website:
- Employ cultural changes as well as physical or biological controls whenever possible to address problems.
- Use chemical controls only when necessary. Choose the least toxic options and use them judiciously. Thoroughly read pesticide labels to ensure safe handling.
- The label must state that the pesticide is for the problem you are addressing.
- Grow Smart Grow Safe website.
- The label must state that the pesticide is for the problem you are addressing.
- Be sure to take any unused pesticides to your local Household Hazardous Waste center for safe disposal.
- Washington State Department of Ecology website; Household Hazardous Waste & Moderate Risk Waste.
GENERAL OVERALL MAINTENANCE
Holidays are just around the corner! If you’re looking for gift ideas for the gardeners in your life, consider:
- Monitor your plants in greenhouses and cold frames for fungal diseases. The added humidity can encourage fungal growth while the extra warmth and shelter may increase unwanted insect populations.
- Check plants under eaves or in sheltered locations. Water if overly dry.
Holidays are just around the corner! If you’re looking for gift ideas for the gardeners in your life, consider:
- Garden tools, especially ergonomic tools, are now manufactured for every need. Arthritis, back problems, carpal tunnel, bad knees, all have tools designed to make gardening easier.
- Ratcheted pruners relieve the strain on aching wrists.
- Contoured and cushioned tool handles are more comfortable for arthritic hands.
- Knee pads and cushioned kneelers protect knees.
- Stationary or rolling seating can take the pressure off backs.
- Grips that slip on long-handled tools make shovels and rakes easier to use.
- Ergonomic tools:
- Garden Gate Magazine publication; Adaptive Tools for Gardeners.
- Garden Design website; 12 Essential Garden Tools for the Beginner.
- Texas A&M University publication; Helpful Gardening Tools and Equipment.
- Gardening books make great gifts and are available for both beginning and experienced gardeners.
- Buy tickets online for individual talks or a season pass to the Winter Speaker Series.
- Presented annually by the Snohomish County Master Gardener Foundation, the Winter Speaker Series begins in January. Professional and university-trained experts cover a broad range of topics with emphasis on gardening in the Pacific Northwest. See the schedule:
- Sustainable Gardening Winter Speaker Series
- Presented annually by the Snohomish County Master Gardener Foundation, the Winter Speaker Series begins in January. Professional and university-trained experts cover a broad range of topics with emphasis on gardening in the Pacific Northwest. See the schedule:
EDIBLES
Maintenance/Clean-up
Maintenance/Clean-up
- Keep weeding, even in winter.
- Check your protective coverings (for example, burlap, cold frame and tunnel covers) to ensure the wind hasn’t displaced them.
- Next year’s seed catalogs are available by mail or on-line. Many are very informative and can help you decide what to plant next year. When ordering from a seed catalog, consider our climate and location. Seed companies from other areas may include information that is not accurate for our area.
- Washington State University (WSU) Extension publication; How to Read a Seed Catalog.
- Seed Starting
- Consider creating a seed-starting station.
- Sanitize containers from past years for reuse.
- Select new seed-starting mix.
- Plan to supplement the light for the station.
- Look for full spectrum or LED light bulbs; grow lights are not required for seed starting.
- Adding heat mats may accelerate germination.
- Plan next year’s garden.
- Consult your notes from this year, and adjust your plans as necessary.
- Keep crop rotation in mind.
- Draw diagrams to help visualize garden plots and raised beds.
- Fruit Trees
- Educate yourself before planting. Before you buy, consult:
- WSU Extension publication; Why Backyard Fruit Trees are not for Everyone.
- WSU Extension publication; Training and Pruning Your Home Orchard.
- Familiarize yourself with potential problems of tree fruits:
- WSU Extension publication; Pest Management Guide for Apples in Washington Home Orchards.
- Educate yourself before planting. Before you buy, consult:
- Small Fruits
- Decide what varieties to purchase later:
- WSU Extension publication; Growing Small Fruits for the Home Garden.
- WSU Extension publication; Growing Winegrapes in Maritime Western Washington.
- Decide what varieties to purchase later:
FLOWERS AND FOLIAGE
Maintenance/Clean-up
Flowers have faded and leaves have fallen, revealing the bones of the garden. Now’s the perfect time to see what might be missing in your landscape. Look for:
- Winter injury protection for trees and shrubs.
- Protect from freezes.
- Rains have probably decreased the need to irrigate; but if a freeze is forecast, check the soil under trees and shrubs. Water well if dry.
- Apply a 3- to 4-inch layer of coarse mulch to help moderate soil temperatures.
- If it snows, consider piling clean snow beneath trees and shrubs to help insulate the ground.
- Protect trunks and branches from cold injury.
- Shade or wrap the trunks of newly planted or thin-barked trees to protect them from frost cracks or other damage. Remove wraps soon after the danger from freezing has passed.
- Washington State University (WSU) Extension publication; Environmental Injury: Winterburn of Evergreens.
- WSU Extension publication; Environmental Injury: Cold Temperature Injury of Landscape Woody Ornamentals (Home Garden Series).
- Prevent breakage after heavy snows.
- Gently shake or sweep the excess from branches that look likely to break or bend.
- Tie limbs of upright evergreens together with twine to help prevent splaying. Arborvitae and yews, especially, have a tendency to open outward under the weight of heavy snow.
- Oregon State University (OSU) Extension Service publication; December Garden Calendar.
- Shade or wrap the trunks of newly planted or thin-barked trees to protect them from frost cracks or other damage. Remove wraps soon after the danger from freezing has passed.
- Pruning
- Hold off on pruning trees and shrubs (except for dead or diseased limbs) until they enter dormancy.
- WSU website; Hortsense; Common Cultural: Winter injury.
- When plants are finally dormant, prune correctly:
- WSU Spokane County Extension publication; Keys to Good Pruning.
- Hold off on pruning trees and shrubs (except for dead or diseased limbs) until they enter dormancy.
Flowers have faded and leaves have fallen, revealing the bones of the garden. Now’s the perfect time to see what might be missing in your landscape. Look for:
- A wide variety of sizes, shapes, and textures in plants.
- Shrubs with colorful berries and trees with interesting bark.
- Cohesion through the use of repetition and color.
- Grasses that provide movement in the garden when breezes blow.
- Focal points to draw the eye.
- Visit garden centers and public gardens for inspiration, taking notes and pictures as you go.
- Snohomish County Master Gardener demonstration gardens:
- Jennings Garden at Jennings Park, 6915 Armar Road, Marysville WA.
- Legion Garden at Evergreen Arboretum and Gardens, 145 Alverson Boulevard, Everett WA.
- Puget Sound Public Gardens:
- Snohomish County Master Gardener demonstration gardens:
- Holiday indoor plants
- Oregon State University (OSU) Extension Service publication; Colorful indoor plants make delightful gifts for the holidays.
- Pennsylvania State University Extension publication; Care and Culture of Winter Holiday Plants.
- When weather permits, and the ground isn’t frozen, continue planting trees, shrubs, groundcovers, and spring-flowering bulbs.
- Hardwood stem cuttings
- When stems are firm and not easily bent, take hardwood cuttings from dormant trees and shrubs, such as forsythia, privet, camellia, yew, juniper, and holly.
- WSU Extension publication; Propagating Deciduous and Evergreen Shrubs, Trees, Vines with Stem Cuttings.
- University of Missouri Extension publication; Home Propagation of Garden and Landscape Plants.
- When stems are firm and not easily bent, take hardwood cuttings from dormant trees and shrubs, such as forsythia, privet, camellia, yew, juniper, and holly.
LAWNS
Maintenance/Clean-up
Maintenance/Clean-up
- Keep mowing as needed, mowing slightly higher than usual.
- If you did not fertilize already, you can still apply it after the last mowing of the season. Be sure to use a slow-release fertilizer before the soil freezes.
- Washington State University (WSU) publication; Winterizing Your Yard.
- Rake leaves off the lawn or mulch-mow them.
- Washington Department of Ecology publication; Natural Yard Care for Western Washington.
- Walk on the grass as little as possible to avoid soil compression damage.
- WSU Extension publication; Lawns - Tip Sheet #11.
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PLANT OF THE MONTH - DECEMBER
Oregon grape
Mahonia cultivars
Mahonia x media 'Charity', Mahonia x media' Winter Sun'
(Ma-HONE-ee-ah)
New family name: Berberidaceae
Mid-winter, natural food for the hummingbirds? A splash of bright, sunny color and fragrance for the gardener? Yes, please! Mahonias will bloom in darkest winter, feeding the overwintering Anna’s hummingbirds.
Oregon grape
Mahonia cultivars
Mahonia x media 'Charity', Mahonia x media' Winter Sun'
(Ma-HONE-ee-ah)
New family name: Berberidaceae
Mid-winter, natural food for the hummingbirds? A splash of bright, sunny color and fragrance for the gardener? Yes, please! Mahonias will bloom in darkest winter, feeding the overwintering Anna’s hummingbirds.
- Mahonias are slow-growing, evergreen shrubs.
- Many Mahonias have dramatic whorls of spiny leaves that are very similar to holly plants.
- An exception to sharply toothed leaves is ‘Soft Caress’ which has bamboo-like whorls of barely toothed leaves.
- The pollinator- and hummingbird-adored, golden bloom clusters appear in fall to winter.
- These nectar-rich plants provide an important food source in winter for hummingbirds which must feed frequently.
- In late summer to autumn, the grape-like blue-black berries feed many bird species.
- They thrive in full sun to dappled shade (deep shade makes a leggy plant), and in any soils, except soggy soil.
- Mahonias do not like to be moved, so site them with that consideration.
- They are winter hardy in zones 7-9.
- Mulch to protect the roots. Protect from freezing winds that may “burn” leaf tips.
- Prune to thin out crowded branches, or trim the tips to make a bushier plant in spring.
- If Mahonias are not happy with the conditions, they are susceptible to diseases such as rust or powdery mildew.
- Mahonia aquifolium is native to our region. There are several cultivars praised for less leggy growth, more stunning blossoms, fragrance, and disease resistance.
- Mahonia x media ‘Charity’ rises to 15 feet and blooms in fragrant, slender clusters over an extended winter period.
- Mahonia x media ‘WInter Sun’ is shorter at 4-10 feet and is said to have the best fragrance. Hummingbird- enticing flower sprays are held at the very tops of branches.
- Mahonia repens, also a native, is a creeping ground cover that has tight clusters of yellow flowers rather than upright sprays. The leaves may turn purple in winter.
- General information on Mahonias:
- Great Plant Picks: Mahonia x media ‘Winter Sun’.
- Great Plant Picks: Mahonia repens.
- Photo credit: Mahonia × media ‘Winter Sun’; Richie Steffen; Great Plant Picks.
- Photo credit: Mahonia repens; Richie Steffen; Great Plant Picks.