McLennan’s
Winterizing Tips

WATERING

Deep, infrequent watering establishes deep root systems which allow plants to withstand periodic, not prolonged, droughts.  Even established plants need water now.

Shallow, frequent watering establishes surface root systems that dry out quickly making plants susceptible to a host of stresses, particularly in drought conditions.

Continue regular watering practices until the ground is frozen in the fall.

Pay special attention to watering regimens for new plants (installed this summer and last summer).  You want to establish a good root system as we head into winter.

If the top two inches of soil are dry give the plant plenty of water.  If the top two inches of soil are moist hold off and check again in a day or two.

MULCHING

Apply mulch at a depth of 3” to help retain moisture and moderate soil temperatures.

Keep mulch away from the stems of trees and shrubs.  Bark is like skin: it does not fare well when constantly moist.

Maintain a crisp edge between planting beds and turf.  This gives a professional landscaped appearance.

Tender shrubs and perennials (such as hybrid roses and butterfly bush) benefit from mulch heaped right into, around and over the lower 1/3 of the plant.  This type of heavy mulch application should be done when the ground is nearly frozen (about one month after the first frost, typically around Thanksgiving).

PERENNIALS AND ANNUALS

Let perennials die down to the ground naturally.  This allows them to store energy and nutrients in their roots for the winter so they will be ready to burst forth in the spring.  Cut back and discard the dead aboveground plant material to reduce the risk of disease and limit winter shelter for pests.  Mulch the soil to moderate soil temperatures.  You can also cover tender perennials and bulb beds with evergreen boughs that will trap snow for an additional winter blanket.

Remove spent annuals and replant with fall annuals including mums, violas, and kale.

PRUNING

Grasses

Ornamental grasses can be cut down to about 8” in the fall or, if they are still looking good, wait and cut them down in the spring.  Cool season grasses, for example, Karl Foerster Feather Reed Grass should be cut down quite early in the spring (March/April) before new growth emerges.  Warm season grasses (for example, Fountain, Zebra, and Maiden Grasses) emerge quite late in the spring.  Cut these grasses down to about 8” in May or June.

Evergreens (Conifers)

With few exceptions, evergreens require little, if any, pruning.  Different types of evergreens should be pruned according to their varied growth habits.

Spruces (Picea), Firs (Abies) and Douglas Firs (Pseudotsuga) don’t grow continuously, but can be pruned any time because they have lateral (side) buds that will sprout if the terminal (tip) buds are removed.  It’s best to prune them in late winter, before growth begins but some spring pruning is not harmful.

Pines (Pinus) put on a single flush of tip growth each spring and then stop growing.  Prune before these “candles” of new needles become mature.  Pines do not have lateral buds, so removing terminal buds will take away new growing points for that branch.  Eventually, this will have dead stubs.

Pines seldom need pruning, but if you want to promote more dense growth, remove up to two-thirds of the length of newly expanded candles.  Do not prune further back than the current year’s growth.

Arborvitae (Thuja), Junipers (Juniperus), Yews (Taxus), and Hemlocks (Tsuga) grow continuously throughout the growing season. They can be pruned any time through the middle of summer.  Even though these plants will tolerate heavy shearing, their natural form is usually most desirable, so prune only to correct growth defects.

Hardwood trees and shrubs without showy flowers

Prune in the dormant season—late fall/winter—for the following reasons:

To easily visualize the structure of the tree or shrub,

To maximize wound closure in the growing season after pruning, and

To reduce the chance of transmitting disease, and to discourage excessive sap flow from wounds.  Recent wounds and the chemical scents they emit can actually attract insects that spread tree disease. In particular, wounded elm wood is known to attract bark beetles that harbor spores of the Dutch elm disease fungus, and open wounds on oaks are known to attract beetles that spread the oak wilt fungus.

Flowering trees and shrubs

To preserve the current year's flower crop, prune according to the following schedule:

Spring Flowering Trees and Shrubs including Redbud (Cercis), Dogwood (Cornus), Lilac (Lilac), etc., should be pruned immediately after flowering.  Spring flowering trees and shrubs form their buds for the next season in the late summer on what is called “old wood.”

Summer and Fall Blooming Trees and Shrubs should be pruned during the dormant season—late fall or winter or very early spring before new growth begins.  These late blooming plants form their flower buds on the new growth (also called “new wood”) which emerges in the spring.

Many flowering trees are susceptible to fireblight, a bacterial disease that can be spread by pruning.  To limit the spread of fireblight varieties of Crabapple (Malus), Hawthorn (Crataegus), Pear (Pyrus), Mountain Ash (Sorbus), Flowering Quince (Chanomeles) and Firethorn (Pyracantha) should be pruned during the dormant season only.

Dead branches can and should be removed any time of the year.

PROTECTING PLANTS FROM WINTER SUN AND WIND DAMAGE

Stake young trees with at least 3 stakes.  Do not wrap rope or wire around the bark of a tree as it will certainly cut through the bark.

Create windbreaks of burlap or other material especially for newly planted evergreens exposed to cold, dry northwest winter winds.

Apply anti-desiccants for needled and broadleaved evergreen trees and shrubs.  Broadleaved evergreens include Rhododendrons, Azaleas, Boxwoods, Hollies, Inkberries, and the Viburnums with persistent leaves.  A popular anti-desiccant (also known as anti-transpirant) is Wilt-Pruf.  These products help to reduce moisture loss through a plant’s foliage.  The first application should be around Thanksgiving with a second application in February.

Wrap the trunks of very young trees and/or trees with thin, smooth bark.  Be sure to remove the trunk wrap in the spring so it won't restrict growth or become a haven for pests.  You can also use perforated flexible tile to create an effective barrier.  Do not use black tile because it absorbs too much heat.

PROTECTING PLANTS FROM CRITTERS (Deer, Rabbits, Mice, Voles, etc.)

Fencing—Must be sturdy and tall enough to keep deer out and anchored at the ground to deter rabbits.

Repellents—There are many effective repellents on the market to thwart deer and rabbits.  Many work well but need to be reapplied at intervals throughout the season.

Provide an alternative high-calorie food source such as apples, carrots, and feed pellets.  Be sure to place the food far away from your plants and be aware that you will likely need to maintain the food supply for the entire winter season.

Let your dog(s) run through the yard on warmer days.  Their presence and scent help deter invaders.

Consider planting critter resistant plants.  Be aware, however, that deer, rabbits, mice and voles will try anything they can get when they are hungry.

FALL FERTILIZING

Fertilizers

Every package of commercially available fertilizer is labeled with a formula in the form of #-#-#.  These numbers represent the ratio of Nitrogen, Phosphorus, and Potassium in that fertilizer.  The short form of these ingredients is N-P-K.  Thankfully they are always listed in the same order.

It is useful to understand the nutritional effects on plants of these ingredients.

Nitrogen—contributes to a plant’s top growth, or foliage, the greenery above ground

Phosphorus—contributes to the development of a plant’s root system, to fruit and flower development, and to disease resistance (Bone Meal is high in phosphorus)

Potassium (or, Potash)—contributes to cell function and the absorption of trace minerals.  It also helps plants to resist diseases, protects them from the cold and protects during dry weather by preventing excessive water loss

It is not unusual to use different mixes at different times of the year for different plant types.  For example, a time-released, balanced mix where each of the numbers is the same (e.g. 10-10-10 or 12-12-12) might be used to fertilize flowering shrubs and trees in the spring and again in mid-summer.  A high nitrogen fertilizer with lower phosphorus and potassium—an example is Miracle-Gro 12-4-8—is typically given to annuals because it’s the greenery and flowers we care about rather than roots and cell function.

When in doubt a time-released, balanced mix is always best.  We do not recommend late summer/early fall fertilizer applications for trees and shrubs when they are still actively growing.  The flush of new growth at the end of the season will not have enough time to harden off before winter sets in.

Time-released fertilizers are recommended because the ingredients are released slowly through a permeable coating around the fertilizer granules rather than a super blast all at once.  These products are activated by ground temperatures.  A nice feature is that any time-released product left in the soil as winter temperatures set in will be activated in the spring well before you or I are out there working in the garden.

Late Fall Fertilizing of Deciduous Trees and Shrubs

Late fall is approximately one month after the first killing frost.  At this time, deciduous trees and shrubs have lost their foliage for the year and active growth of plants and trees has slowed.  Rather than put on new foliage growth, the roots of established trees or shrubs take the nutrients from the soil and apply them to important health-promoting functions such as disease resistance and root development.  The excess nutrients are stored in the roots and become immediately available when needed for new growth in spring.  Use a balanced time-release product.

Late Fall Fertilizing of Needled and Broadleaved Evergreen Trees and Shrubs

Same as for deciduous trees and shrubs but select a fertilizer specifically formulated for these types of acid-loving plants.

Always water generously before and after fertilizing.

LAWN CARE

As the days get shorter and cooler, growth slows and grass plants prepare for dormancy.  While northern turf grasses such as Kentucky bluegrass, tall fescue and perennial rye actually prefer cool weather, some winter precautions are, nonetheless, in order.

For a conservative approach apply a slow-release, balanced lawn fertilizer in early September.  Always water lawns before and after fertilizing in a dry season.

For a more aggressive approach you might try this: In early September grass is recovering from a long hot summer and may be coming out of a drought-induced dormancy, so give your lawn a shot of nitrogen to push blade growth.  A fertilizer with a formula of 20-8-8 will get it growing again.  At the end of October/early November apply a fertilizer with a formula of 13-25-12 to encourage root growth rather than top growth.

Lower your mower’s blades by 1 notch for the last month of summer.  The closer mowing removes older parts of grass blades made up of frost-sensitive cells.  New, hardier “tillers” keep growing, but slowly.  This treatment helps grass resist browning and matting in soggy winter weather.

If possible, aerate your lawn and use a stiff-tined garden rake to pull out dead grass and let in winter's renewing rains.

Apply compost with a spreader to add organic matter.

Overseed bare areas in early fall to take advantage of cooler weather and fall rains.

Mow over the last thin layer of fallen leaves with a mulching mower.  The confetti-like pieces of leaves that fall among the grass blades mulch the grass plants and help protect lawn soil.

Avoid walking on turf after the final mowing of the season if the soil is frozen.  Brittle, frozen grass is easily damaged by foot traffic.  The ice crystals that form inside cell membranes of grass foliage rupture cell walls when they are walked on.