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Space Availability and Plant Selection for a New Hedge

It is important to plan the layout of a screen or hedge before installation. Once trees or shrubs are planted and begin growing, it can be difficult to make changes. Factors to consider include the available space on the property; whether it will be a formal or informal design; the need for deciduous or evergreen plants; the aesthetics of plant texture; and, in areas prone to wildfire, the need for defensible space. One of the biggest design mistakes made is planting species that are too large for the designated area.

Photo credit: Charles Brun, WSU Horticulture Specialist, emeritus

Photo credit: Charles Brun, WSU Horticulture Specialist, emeritus

The WSU publication Selecting Plants for Screens and Hedges EM089E  can help with the many questions regarding planning, design and plant selection of a new hedge

Submitted by: Paula Dinius, May 11, 2016


I didn’t get my spring bulbs planted yet. Is it too late?

Ideally, spring bulbs need to be planted in early November or before the first hard frost in your area. However, bulbs are also very forgiving and may still bloom even when put into the ground as late as early March.


Wikimedia commons, “2015-04-27 Tulip,White and Red in Sasayama, Hyogo Japan

Bulbs grow and bloom the best when planted in an area that receives direct sunlight and adequate moisture. They can be planted in groupings (3 or more) or in a straight line depending on available space in your planting location. It is a good idea to think about the height of the bulbs, not just the color, if you are planting several different types in the same area in order to create a pleasing display.

For more information, see the WSU publication PNW164 “Propagation of Plants from Specialized Structures.”

Submitted by: Sheila Gray, March 7, 2016


Horticultural Oils

It is fairly easy to accidentally damage your plants or nearby environments when applying horticultural oils. Here are some important points to consider before using these oils:

juniper_PetiteHorticultural oils are non-specific so if beneficial insects get sprayed, they will die along with the insect pest.

Only spray plants with confirmed pest problems in order to conserve the beneficial insects in your garden and landscape.

Be aware that junipers and spruce often lose their blue color when oil is applied.

Oil and water do not mix: horticultural oil will inhibit oxygen transfer, which can kill fish. Keep applications and their airborne oil drift out of waterways.


For information on how to use horticultural oils successfully, see the WSU Extension fact sheet Pesticide Ingredient: Horticultural Oil.

Submitted by: Catherine Daniels, Jan. 7 2016


Do cedar mulches kill other plants?

Many living, growing woody plants contain allelopathic chemicals, which can prevent seeds from germinating or kill young seedlings. Most compounds have no effect upon established plants. Cedars (Thuja spp.) have not been found to have this ability. Even Juglans nigra (black walnut), the best known allelopathic species, has not been shown to have negative effects when wood chips are used as a mulch.

Wood chip mulches are beneficial to established plants.

Wood chip mulches are beneficial to established plants.

For more information on wood chip mulches, see “Using Arborist Wood Chips As a Landscape Mulch” WSU Extension Fact Sheet FS160E.

Submitted by: Linda Chalker-Scott, November 2, 2015


Fall Garden Tips: Time to Plant Garlic

In the Northwest, garlic is planted as cloves in the fall. Garlic requires full sun (at least 6 hours per day). It is best started by direct sowing seed garlic that can be purchased through some garden centers, catalogs, and online websites. Certified seed garlic has been grown specifically for planting in the garden and is free of insects and diseases.

Plant garlic in early to mid-fall (September to October) in eastern Washington gardens and late fall (November) in western Washington gardens. To prepare the planting area, loosen the soil to improve drainage.


Plant large cloves that are clean and dry and plant them the same day the bulb is broken apart. Cloves showing any discoloration, stippling, or bruising should be discarded. Plant the cloves so that the tops are 2 inches below the soil line, and place the garlic clove flat-side down and pointed-side up in the hole. Garlic should be planted 4–6 inches apart in rows that are spaced 12–24 inches apart.

For more information on growing garlic, see Growing Garlic in Home Gardens.

Submitted by: Nicole Martini, October 26, 2015


Harvesting Winter Squash

Winter squashes are harvested fully mature when the skins feel hard and waxy. In autumn, there is no hurry to harvest winter squashes unless excessively cold or wet weather is approaching. Pick winter squashes with stems attached. Cure in a warm, dry place and store at room temperature. Under these conditions, winter squashes store between 3 to 5 months. After the final harvest, be sure to remove and destroy the leftover plant debris. Alternatively, turning under the remaining plant material into the garden soil can help replenish nutrients and contribute to the organic content of the soil.

Photo credit: Trevor Mattea, Wikimedia Commons

Photo credit: Trevor Mattea, Wikimedia Commons


For more information please see WSU publication Growing Squash in Home Gardens FS087E

Submitted by: Catherine Daniels, Oct. 21, 2015


Will woody mulch acidify my soils?

In field situations it is difficult to significantly alter soil pH without the addition of chemicals. Temporary changes in pH may be found in the decomposing mulch layer itself, but these have little effect on underlying soils. Significant changes in soil pH can only occur after decades or centuries of mulch use.

pine needles

For more information on wood chip mulches, see “Using Arborist Wood Chips As a Landscape Mulch” WSU Extension Fact Sheet FS160E .

Submitted by: Linda Chalker-Scott, October 12, 2015


PEST WATCH: Brown Marmorated Stink Bug

The brown marmorated stink bug (BMSB) causes damage to agricultural crops and is an annoyance to homeowners.
Beginning in September, BMSB adults aggregate in large masses often on the sides of homes and other buildings. They enter structures to avoid cold weather. While stink bugs are not known to harm people or cause damage to buildings, they can be quite distressing when large numbers of individuals enter households.

Brown mamorated stink bug on holly (Todd Murray)

Brown mamorated stink bug on holly (Todd Murray)

Sealing cracks, mending screens, and screening vents mechanically exclude BMSB adults from entering houses. When aggregations begin to form, regular vacuuming of BMSB adults has helped reduce the number entering houses.
If you suspect you have BMSBs in a new region of Washington State, please collect a sample in a crush-proof container, note the date and specific location, and place it in a freezer until you can take it to your local WSU Extension office or local Master Gardener clinic.

For more information on the Brown Marmorated Stink Bug see WSU’s Pest Watch: Brown Marmorated Stink Bug FS079E.

Submitted by: Todd Murray, October 5, 2015


Protect Your Young Apple Trees from Renegade Rabbits


If you have seen cute little bunny rabbits romping in your young orchard over the summer, don’t be surprised if you start seeing damage to your young fruit trees. Rabbits nip off the tops and gouge the bark of stems in winter. During winter, rabbits and hares remove “chips” of bark and wood from thin-barked woody plants, sometimes girdling the entire trunk.



Washington State is home to several species of rabbits and hares. Of these, only the snowshoe hare and the introduced Eastern Cottontail commonly damage gardens, orchards and landscapes.
To prevent winter damage to your young trees and shrubs from “wascally wabbits”, you can keep them away from the plants by:

• using wire or plastic tree guards, or
• wrapping lower trunks with burlap or wire mesh, or
• using rabbit-proof fencing, or
• applying rabbit repellents registered for home use.

Remember to reduce hiding places near your garden or orchard by eliminating thick brush, including brush piles, and by placing screens over openings under outbuildings. This will help reduce the number of rabbits and hares around your home and protect your landscape plants.

Submitted by: Dave Pehling, September 28, 2015


Why are my conifers losing foliage?

In the fall, after a long, dry summer, an evergreen conifer may not have enough resources to sustain all of its green foliage; thus, it will shed its oldest foliage (i.e., the foliage found on the innermost part of a branch). In doing so, the tree is prioritizing its resources. The oldest foliage is the least productive because it has become dirty over time and, being on the interior of the branch, receives the least amount of sunlight. The tree will sacrifice this older foliage in favor of the newer, more productive foliage.


Ladd Livingston, Idaho Dept of Lands,

Although the tree’s appearance may be somewhat alarming, this seasonal foliage loss is a normal part of conifer growth. The foliage loss is particularly noticeable in western redcedar, where it is referred to as “flagging.”

Seasonal foliage loss can also be particularly pronounced in pines. Some years seem to have particularly pronounced seasonal dieback, depending on weather patterns and other stress factors. Thus, even when a tree has excessive interior needle loss, it is not necessarily an indicator of disease, insect attack, or other unhealthy conditions. There are some insects and disease agents that tend to attack a tree’s oldest foliage, but these agents usually leave signs of their activity, such as chewing or speckling across the older foliage.

You’ll find more information about seasonal foliage loss here.

Submitted by: Tim Kohlhauff, September 21, 2015


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