Washington State University Extension

Garden Tips

Archive for September 2011


written by
Marianne C. Ophardt
WSU Extension Faculty
for the Tri-City Herald, Kennewick, WA

I’m often asked about the best trees to plant in our area, but usually not about the worst trees to plant. My reasons for deeming a tree ‘the worst’ is its extremely large mature size; susceptibility to disease or insect pests that are difficult to impossible to control; invasive roots; and weak wood prone to breakage from wind and ice. So what trees do I advise against planting on the normal home lot? Here goes…

Silver Maple (Acer saccharinum): Silver maple is a common older tree in our area, planted in years past because of it’s fast growth. However, with fast growth comes weak wood and invasive roots. Silver maple is also a very large tree when it reaches maturity, much too big for today’s average home landscape. Plus, as silver maple ages, surface roots become a significant problem, lifting sidewalks and making lawn mowing difficult.

Ash (Fraxinus americana and Fraxinus pennsylvanica cultivars): Ash trees are well suited to our soils and perform quite well until they’re attacked by the ash borer which has become prevalent in our region. There is no practical control for ash borer, so the longevity of an ash tree in a home landscape is questionable.

Quaking Aspen (Populus tremuloides): Who doesn’t like the trembling leaves and the spectacular golden fall color of aspens? Many folks love this tree until it’s been growing in their landscape for a couple of years. That’s when the aspen roots start sending up suckers, lots of suckers. According to research, aspen roots start suckering when they’re about two years old and one-quarter inch in diameter, plus aspens develop extensive root systems. This explains how native aspen stands grow larger and regenerate themselves after forest fires. In home landscapes this ability becomes a nightmare.

Hybrid Poplars (Populus sp.) Hybrid poplars are created by breeding two or more poplar species together. Because poplars are some of the fastest growing trees in northern temperate zones, plant breeders have worked at creating hybrid poplars that are very fast growing for pulp, energy, and lumber production. However, the title ‘hybrid’ doesn’t equate to a good landscape shade tree. Poplars and hybrid poplars tend to be short-lived (15 years or less) because they’re prone to trunk canker diseases. They also have shallow, invasive roots and weak wood. Depending on the hybrid they may also produce cottony seed masses and root suckers.

Willows (Salix sp.) There are a variety of large fast growing willows planted as shade trees in home landscapes. This includes weeping willow (Salix spp.); the Austree willow, a cross between Hankow willow and white willow; and corkscrew willow. These are nasty trees with very aggressive roots that spread out as far as the tree is tall and farther. These roots proliferate where water is available and can damage irrigation lines, sewer lines, and septic system drain fields. Willows also have weak wood, shallow roots, and are prone to canker disease. All of this contributes to making them relatively short lived (30 years) shade trees.

While some trees are not well suited to the normal home landscape, most trees have some redeeming value. Willows will tolerate fairly wet soil, where many other trees won’t. Poplars and willows with invasive roots can be used to stabilize soil on river and stream banks. Fast growing trees can serve as temporary windbreaks until slower growing species have a chance to grow. However, the trees on my ‘worst list’ should usually be avoided. There are many other better choices for planting in your landscape.
Published: 10/1/2011 12:18 PM


written by
Marianne C. Ophardt
WSU Extension Faculty
for the Tri-City Herald, Kennewick, WA

This is the time of year gardeners start to prepare their gardens for winter. It’s also the time of year that Halloween decorations start to appear. Ghouls, monsters, pumpkins, spiders, and bats seem to be a pervasive theme. Halloween is all about spooky and scary things, but we do an injustice to spiders and bats who are actually two of our garden friends. Making them out to be frightening creatures is unjust.

Generally, spiders should be regarded as good guys. Why? According to Dr. Linda S. Rayor, Assistant Professor of Entomology, Cornell University, ‘Spiders are considered to be the most important terrestrial predators, eating tons of pest insects or other small arthropods every year. Spiders are generalist predators that are willing to eat almost any insect they can catch. They are abundant and found in most habitats. They only need to be left alone!’

That’s why I get upset when I hear about folks who want to spray around their homes to kill all the spiders and other insects because one or two might find their way inside. This certainly knocks the balance of nature out of kilter. When spiders migrate inside at this time of year looking for a mate or a warm spot to spend the winter, just smash them with a shoe or tissue. If you have lots of spiders migrating indoors, it probably means that you need to tighten up your home, replacing weather stripping on doors and sealing cracks and crevices that provide entry to spiders and other creatures.

A common ‘scary’ spider noticed at this time of year are the orb weavers (Araneidae). There are a variety of different orb weavers, some with interesting angled peaks or tubercles on their large abdomens. They can also be quite colorful, coming in a variety of colors including orange, yellow, black, white, and brown.

A female orb weaver can appear quite large at this time of year because she is carrying several hundred eggs in her abdomen. Before the end of fall she will create an egg sac and then die before winter arrives.

The orb weavers build amazing large wheel-like circular webs that are works of art. When insects find their way into an orb weaver’s web, their vibrations enable the spider (orbs have poor vision) to locate and trap their hapless victims. Most orb weavers rebuild their webs every day.

So if you see spiders or their webs around your yard and garden don’t be alarmed. Don’t try to kill them. They’re helping keep insect populations in check. If you see spiders inside the house, just usher them back outside where they can do some good or smash them.

Bats also eat a tremendous amount of insects, including mosquitos, and should be considered our friends. As with spiders, by encouraging bats we’re allowing nature to keep the insects in our yards and gardens in check.
Published: 9/29/2011 12:10 PM


written by
Marianne C. Ophardt
WSU Extension Faculty
for the Tri-City Herald, Kennewick, WA

It’s hard to believe that autumn is right around the corner, although cooler temperatures are a sign that we should be starting to make our list of fall gardening chores now. At the top of my list is planting more spring flowering bulbs. I must admit my past efforts in this arena have been haphazard.

This fall I want to do it right… plant more spring flowering bulbs with a plan in mind. Bulbs can be costly, so it’s good to make the most of this expense by keeping some simple bulb design principles in mind.

Whether planted by in beds by themselves or integrated into landscape and perennial beds, bulbs make the biggest visual impact when planted in masses of one color and one variety. They will look more natural if they’re placed in irregular groups instead of a line of ‘little soldiers.’ Twelve or more tulips or daffodils qualify as a ‘group.’ The bigger the group, the bigger the affect. When it comes to smaller flowering bulbs, like crocus or grape hyacinth, fifty or more is a good size ‘group.’

The experts at the Netherlands Flower Bulb Information Center point out that gardeners should think of spring as three seasons in one…early, mid, and late spring. That’s because different bulbs bloom at different times in the spring. Everyone has seen pictures of crocus in bloom with snow on the ground, so obviously crocuses are early spring bloomers. However, not everyone knows that some types of bulbs, such as tulips and daffodils, have different varieties that are designated as early, mid, or late season bloomers.

Luckily for us, most of the companies who grow and sell bulbs indicate for each type and variety whether it blooms in early, mid or late spring. Keep in mind that these blooming times are all relative, with bulbs blooming earlier or later depending on the area weather and the climate of the region.

If your bulb budget is limited, use a little trick to make it seem like you’ve planted more bulbs than you did. Rather than planting your ‘groups’ of bulbs in irregular circles or ovals, place them in rough triangular groups with the narrowest point of the triangle facing front ward.

If you only have limited space available for planting spring flowering bulbs, you can create an effective display by planting in layers. Start by placing your larger tulip and daffodils in the bottom of a planting hole using the recommended depth and spacings. Cover them with soil and then in the same hole, plant smaller flowering bulbs such as crocus, species tulips, and scilla at the shallower recommended depths.

Bulbs are starting to show up in local garden stores now, so I’d better get busy and decide what and where I want to plant my bulbs. If I don’t hurry up, all the bulbs that I want will be gone!

Published: 9/17/2011 11:59 AM


written by
Marianne C. Ophardt
WSU Extension Faculty
for the Tri-City Herald, Kennewick, WA

I’ve admitted in the past that I’m a sucker for garden gadgets and tools, so when the A.M. Leonard catalog arrived in the mail, I was tickled to flip through the pages to see what I could find. A.M. Leonard is a Horticultural Tool and Supply company geared towards horticultural professionals but with many handy tools and gadgets that appeal to home gardeners too.

The very first item I noticed was on the cover. It’s the ‘Nut/Fruit Wizard’ which looks perfect for picking up walnuts, apples, and other hard fruit without bending over. This gadget has a spherical head made of horizontal strands of spring wire. All you have to do is run it over the fruit or nuts lying on the ground and the head traps them. When full, you just spread the wires open to dump out the load. The fruit needs to be firm, so it won’t work on ripe plums or mushy apples, but it does work with golf balls.

I usually cringe when I see how trees are staked in commercial and home landscapes. Most are tied fast to stakes with materials that can dig into the tender bark of the young trees. Leonard offers ‘Tree Saver Staking Kits’ that tie a tree to metal stakes in the ground using strong yet flexible rubber straps. The rubber straps allow a tree to sway some in the wind, but still stay upright. Swaying of a tree stimulates the production of growth regulating hormones that stimulate root growth and trunk development. A staking system that allows for some movement of the trunk will result in a healthier tree.

At my previous house, wild barn cats used the smooth bark of my young red maple trees as scratching posts. Darn cats! I wish I had known about ‘Tree Bark Protectors.’ These are 4 inch diameter tubes made of open, hard but flexible, plastic mesh . They can be easily placed around tree trunks to protect them from cats, rabbits, deer, squirrels, woodchucks, and weed trimmers. They’re sold in bundles of five and come in either 2, 3, or 4 foot lengths.

In our bright and hot sunny climate, some trees, especially those with dark bark like cherries, benefit from protecting their trunks from sun and heat during the first year or so after planting or risk damage from sun scald. Generally, the only option for protecting tree trunks has been to apply interior white latex paint to the trunks to reflect the sun. A.M. Leonard offers their own ‘Corrugated Tree Guards.’ These are 3-inch diameter tubes made out of corrugated HDPE resin. The outside is white to reflect sunlight and there are vents along the tube to allow for air circulation. They’re sold individually and also come in either 2, 3, or 4 foot lengths.

Leonard also offers an interesting line of equipment for precise application of herbicides, such as glyphosate (Roundup). This includes the Sideswipe with a wipe-on applicator and protective shield that puts the herbicide only on the weeds; the Weedball Applicator where the herbicide comes out of a roll-on applicator that’s designed for treating along fence lines, edging or in tight places; and the Weed Stick that can be used to spray herbicides or insecticides directly onto a plant under a shield.

They even sell a floating ‘gator’ head to scare birds and animals away from your pond and a lifelike menacing coyote for scaring cats and dogs away? The Leonard catalog is free, just contact them at 1-800-543-8955 or
Published: 9/10/2011 11:50 AM


written by
Marianne C. Ophardt
WSU Extension Faculty
for the Tri-City Herald, Kennewick, WA

Whether your lawn is pampered or neglected, weed free or overcome with weeds, fall is the most important time of the year to give it the attention it deserves.

Summer heat stresses the cool season turf grasses in our lawns. As the weather cools in early fall, lawns start to recover. You can help that recovery along with properly timed fertilizer applications. An early September (Labor Day) plus a late October (Halloween) or early November application are recommended for our region.

You still need to irrigate your lawn, but as the weather cools you should be cutting back on the amount of water being applied. If you’re watering everyday, you may only need to water every second or third day. By watering everyday when the lawn doesn’t need it you’re wasting water, washing away needed nutrients, and encouraging the growth of weeds.

Weed Management:
One of the best ways to manage lawn weeds is to encourage a healthy turf with properly timed fertilizer applications and irrigation. However, weeds still find their way into lawns and October is the best time to apply herbicides for the control of broadleaf weeds. That’s because many of the perennial broadleaf weeds in our lawns, such as dandelions and plantain, are actively growing during the cool fall weather. Herbicides applied when they’re actively growing are more effective.

There are also winter annual broadleaf weeds, such as chickweed, that germinate in the fall and grow during late fall and early spring. These are more easily controlled in the fall when the plants are young and small. Efforts made in the fall to encourage a dense, healthy turf, can also help control summer annual weeds, such as crabgrass, purslane, and pigweed, that will germinate in the spring. A dense turf makes it more difficult for weeds to germinate and grow.

Also, fall is a good time of year to apply herbicides to your lawn because landscape plants are not actively growing and not as susceptible to damage from the herbicides.

Which Herbicides?:
There are a number of broadleaf weed control products on the market. Most broadleaf lawn weeds can be controlled with a combination of 2,4 D, MCPP, and dicamba. However, products containing dicamba should not be used in the root zone of desirable trees and shrubs because they can cause damage. This includes trees and shrubs growing in the lawn area or along the lawn border. Even if trees and shrubs are in a landscape bed, they’re still vulnerable if their roots are growing into the lawn area. Keep in mind that the absorbing roots of a tree can be located in areas as far from a tree as that tree is tall and beyond! If you have vulnerable plants with roots throughout the lawn, it would be advisable to simply spot treat weeds or use a product that doesn’t contain dicamba.

There are also certain lawn weeds that are particularly difficult to control, including bindweed, black medic (Japanese clover), clover, creeping wood sorrel (oxalis), ground ivy, henbit, mallow, prostrate spurge, violet. Better control of these can be achieved with lawn herbicide products containing triclopyr.

Before purchasing any herbicide product for your lawn, identify the weeds you’re trying to kill. WSU Master Gardeners can help you identify your weeds. Just dig them up and place them separately in zipper-locked plastic bags. Bring them to the Extension office (735-3551) in Kennewick in the Benton County Annex at 5600-E West Canal Dr. Of course, read and follow all label directions and precautions on the herbicide product you select.
Published: 9/3/2011 11:48 AM


written by
Marianne C. Ophardt
WSU Extension Faculty
for the Tri-City Herald, Kennewick, WA

Last year I got very exited about an article I read in the June issue of ‘Fine Gardening’ magazine. It was titled ‘Build a Garden Out of Straw,’ by Amy Stewart. Straw bale gardening is a hot new trend in many areas, but gardeners like Stewart that have successful straw bale gardens are located in areas with much cooler summer climates. I wondered if they would work here in the Tri-Cities.

First, what’s a straw bale garden? A straw bale garden is a ‘conditioned’ bale of straw where plants are growing in the straw bale, instead of in the soil. All sorts of vegetable crops can be grown in the bales, including garden favorites like tomatoes, peppers, squash, and melon.

Why garden with straw bales? Straw bale gardens are inexpensive, they don’t require any digging, they can be placed on a patio or driveway, and they’re temporary. Also, the bales create a raised bed situation, making gardening easier with less bending.

A number of local gardeners have adopted square foot vegetable gardening where intensive methods of growing vegetables are utilized. However, square foot gardening requires building structured permanent beds, dividing the beds into one-square-foot grids, and carefully following a schedule for planting, harvesting, and replanting for successive cropping in each square. It takes an attentive gardener to manage a square foot garden well.

In addition, the recommended soil mix used in the square foot garden beds is prohibitively expensive for many. Oat or wheat straw bales are inexpensive ($3 to $5 a piece) and no building materials are required. The only other expenses include a bag of inexpensive fertilizer, such as 21-0-0 to condition the bales before planting, a complete water soluble fertilizer for fertilizing the growing veggies, and some quality potting mix.

To condition the bales and get them ready for planting, they’re first watered thoroughly and then fertilizer is spread across the top of the bale. This jump starts the decomposition of the straw. After two to three weeks the bales are ready for planting. Transplants or seeds can be used for planting in the straw bale. After planting, regular watering and fertilizer are needed to keep the veggie plants healthy and growing.

The bales only last one season, two at the most. When they no longer have integrity as a bale, the partially rotted straw can be composted or tilled into the soil.

This spring, one of our local Master Gardeners, Eileen Hewitt, decided to give straw bale gardening a try. Her home sits on very hard, rocky ground in Kennewick where just digging a hole is a monumental task and tilling the ground for a garden is a virtual impossibility.

Hewitt found a source of oat straw bales ($3 a piece) and placed several in her back yard. She followed the step-by-step instructions for building a straw bale garden and planted tomatoes, squash and melons in her bales and now she’s happily harvesting fruit from all her ‘straw bale’ plants.

With such hard soil Hewitt doesn’t plan to use the disintegrating bales of hay for tilling into her yard, but gardening friends have already asked her for the straw when she’s done with the bales. Can we successfully grow straw bale gardens in the Tri-Cities? Hewitt answers, ‘Yes!’ and she plans to grow in straw bales again next year.

A handout on ‘Straw Bale Gardening’ is available by calling the Benton County WSU Extension Office at 735-3551 or on-line at

Published: 8/27/2011 11:33 AM



Garden Tips, WSU Extension, Benton County, 5600-E West Canal Drive, Kennewick, WA 99336-1387, 509-735-3551, Contact Us

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