Washington State University Extension

Garden Tips

Shrubs RSS feed


GARDEN TIPS – Written by Marianne C. Ophardt
WSU Extension Faculty
for the Tri-City Herald, Kennewick, WA Published May 8, 2016

Flowering shrubs were once a staple of home landscapes, but over time they have lost their fan base. Reasons for this loss of popularity may have been their large size and limited seasonal interest. I can recall the Vanhoutte spirea (S. x vanhouttei) in the front of the house where I grew up. In spring it was magnificent when covered with clusters of small white flowers, but the rest of the year it was unremarkable except for its huge size, growing 5′ to 8′ tall and 7′ to 10′ feet wide.

Today, plant purveyors are continually working to offer new flowering and evergreen shrubs for the home landscapes. Many of these are more compact and have multi-seasonal interest, such as springtime flowers, bright fall color, or interesting bark. Other desirable traits include prolonged or repeat bloom, remarkable foliage colors and textures, low maintenance requirements, and pest resistance. Every year I get excited about all the new shrubs being introduced to gardeners and this year is no exception. Here are just a few.

First Editions® Spring Lace Viburnum is being offered by Bailey Nurseries. Viburnums are one of my favorite shrubs, but most tend to be too large for my landscape. However, I might consider planting Spring Lace because it grows only 5′ tall and wide, has dark green leaves that turn dark red in fall, and is covered with flat clusters of fragrant white blooms in spring. Bailey Nurseries says it appears to be fruitless.

I also fondly remember a yellow climbing rose that grew in my grandparents’ yard. It grew very tall and bloomed only once in early summer. Ball Ornamentals is introducing a new series of climbing roses, the Starlet Beauty™ Series, for use in small garden spaces and in patio containers. Ball describes this series as the “elegant little sister of the large-flowered classic climbing roses.” Mauve, pink, ruby or tangerine colored double blooms are produced all season long. Ball touts that the plants are well branched growing 8′ to 10′ tall and 3′ to 4′ wide and can be trained to grow vertically or horizontally on a trellis.

When it comes to boxwood, I am not a big fan because of its odiferous foliage and vulnerability to winter sunburn damage. However, its compact growth works well in more formal landscapes and gardens. Monrovia is introducing Petite Pillar™ Dwarf Boxwood. It is a dwarf columnar boxwood that grows only 2′ to 3′ tall and 2′ wide at the base. Monrovia notes that Petite Pillar can be utilized effectively in containers, in limited space landscapes, or for creating small hedges. It does not need regular shearing to keep it neat and compact.

Every year Proven Winners introduces a bunch of interesting new shrubs. This year one new introduction is a cute little viburnum that will fit into any landscape. ‘Lil’ Ditty’ is a fragrant dwarf viburnum that only grows up to 2′ tall and wide with a mounded form. The creamy white flowers are produced in late spring and may yield a crop of showy black fruit if a pollinator is nearby. Speaking of small, Proven Winners also markets a diminutive forsythia, Show Off® Sugar Baby. It is perfect for the smaller spaces in today’s home landscapes, growing only 18″ to 30″ tall and wide with a mounded form and covered with bright yellow flowers in the spring. It does not require heavy annual pruning.


written by
Marianne C. Ophardt
WSU Extension Faculty
for the Tri-City Herald, Kennewick, WA
Published 3/29/2013

When it comes to shrubs, gardeners today have so many great choices with new shrubs appearing every year, thanks to plant breeders and purveyors. What I like along with the diversity of choices is that so many new shrub cultivars (cultivated varieties) are smaller or more compact, making them easier to fit into today’s smaller yards and landscapes. Here are just of a few of the new smaller shrubs already here or coming to us soon. Ask about them at your local nursery.

One new little cutie is Mr. Bowling Ball® (Thuja occidentalis ‘Bobazam’) a globe arborvitae that doesn’t look like an arborvitae. It grows into a nice little ball of a shrub that reaches 2.5 feet tall and wide. The foliage looks more like a fine needled juniper in both appearance and texture. Like a juniper, it’s sage green in color and doesn’t need any pruning to keep it in round and small, plus it’s very winter hardy.

Anyone who has an original cultivar of dwarf Alberta spruce, probably wonders why it’s called a dwarf. It’s a slow grower, but it will eventually reach a height 6 to 8 feet and a width of 4 to 5 feet. However, the regular Alberta spruce can reach a height of 40 to 60 feet, definitely qualifying the regular dwarf Alberta as a dwarf. New to the market is a more diminutive dwarf Alberta called ‘Tiny Tower®’ (Picea glauca conica


) which reaches a height of only 4 to 6 feet. Like its relatives, it’s very hardy and has needles that emerge a bright green and turn gray green as they mature.

Forsythia is one of the wonderful harbingers of spring. It’s cheery bright yellow flowers shout that spring is on it’s way, but not everyone likes to include them in their landscape. That’s because they have a tendency to become rangy and unkempt. The perfect solution is ‘Show OffÔ Sugar Baby’ (Forsythia x intermedia


) a very small forsythia that reaches a height of only 30 inches and a width of 36 inches. This cultivar produces oodles of flowers and stays small without pruning.

Lo & Behold® ‘Lilac Chip’ (Buddleia x

Lilac Chip

) is a dwarf buddleia (butterfly bush) that stays small, growing only 18 to 24 inches tall and 24 to 30 inches wide. At this small size they easily fit in the perennial garden or a landscape bed. The soft lavender pink flowers are produced all summer up to frost with no need to deadhead to keep the flowers coming. There is no worry that ‘Lilac Chip’ will become invasive like most of the old types of cultivated butterfly bush (on the noxious weed lists in many states) because it’s sterile and can’t reproduce from seed.

One of my favorite flowering shrubs is Caryopteris, also known as bluebeard. They produce true blue flowers in late summer that are magnets for honeybees. One of the newest Caryopteris is ‘Lil Miss SunshineÔ’ (Caryopteris x clandonensis ‘Janice’). This new Caryopteris has yellow leaves from spring through fall and deep amethyst blue flowers in late summer. What a contrast! It grows to a height and width of 30 to 36 inches, making it a great fit for smaller landscapes and garden beds.

I have no doubt that there will be more new small shrubs available next year. If you’re tired of wacking back large shrubs to fit your landscape or want some new plants to fill in empty spots here and there, you should consider these and other smaller shrubs.

Published: 3/29/2013 11:07 AM


written by
Marianne C. Ophardt
WSU Extension Faculty
for the Tri-City Herald, Kennewick, WA
Published 11/30/2012

Have you ever wondered if we can grow palm trees in the Tri-Cities? Do you know how to determine if a palm tree or any perennial, woody tree or shrub will survive the cold winter temperatures in our region?

The simple answer is to find out the plant’s hardiness rating and then check a ‘hardiness zone map’ to see if that plant is rated as ‘hardy’ or able to withstand the coldest temperatures experienced in ‘your zone.’ Hardiness zone maps designate zones based on the average annual minimum temperatures determined from weather data over a span of years.

A number of U.S. hardiness zone maps have been developed. The first one was produced at the Arnold Arboretum in 1927. This map divided the U.S. and southern Canada into eight zones based on 5 degree differences in the lowest mean temperature. It was the 1971 revised version of this map that I consulted when I moved to this area in 1980.

Today, the most frequently consulted hardiness zone map is the USDA Plant Hardiness Zone Map. The USDA map was first published in 1960 and revised in 1965. It divided the U.S. into zones of 10 degree differences. Updated in 1990 using more weather data, each zone was broken into two zones ‘a’ and ‘b’ with 5 degrees of difference.

You wouldn’t think that zone maps would be a point of controversy, but they have been. In 2003 the American Horticultural Society (AHS) took on the task of revising the USDA map again using more recent weather data from July 1986 to March 2002. Because there had been a period of warmer winters in the eastern U.S., some zones changed to a half-zone higher than the map released in 1990. USDA rejected the AHS map because reviewers felt the changes were taking a step backward and didn’t like that it eliminated the half zones (a&b). USDA decided to create its own map.

This year USDA finally introduced its own updated Plant Hardiness Zone Map. This map was developed by USDA

s Agricultural Research Service and Oregon State University

s PRISM Climate Group. USDA feels the new map has greater accuracy and detail, dividing the U.S. into 13 zones with each 10-degree zone divided into 5-degree zones of ‘a’ & ‘b.’

Many areas on the new map tend to be about a half-zone warmer than on the previous map and there were also some zones that are ‘cooler’ than on the 1990 map. USDA points out that this is a result of using data from a longer period of time (30 years from 1976 to 2005) where the 1990 map used data from a much shorter period (13 years from 1974 to 1986) . Changes are also the result of using more sophisticated methods of mapping and the use of temperature data from more stations.

Now back to those palm trees… plants are rated as ‘hardy’ based on the coldest winter temperatures they can survive. On the new 2012 USDA map, most of Benton and Franklin counties is designated as zone ‘7a’ with some limited colder areas of the region rated as 6b. The large palm trees found in California and Florida are generally hardy only in warmer zones of 8b to 11, making them an unwise choice for a Tri-City landscape.

Check the hardiness rating for any perennials, trees, and shrubs you want to plant in your landscape. To see the USDA map go to and click on Washington.

Published: 11/30/2012 2:12 PM


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

I like to keep track of what’s ‘in’ and what’s ‘out’ when it comes to garden trends. Each year garden style setters and marketers reveal the newest garden trends. One of the 2012 trends noted by Better Homes and Garden is the use of dwarf shrubs in today’s smaller gardens and landscapes. This has been made possible by plant breeders who have selected and bred more diminutive versions of yesteryear’s large shrubs.

The passe shrubs were too big for today’s smaller homes and yards. The new ‘mini-me’ shrubs are much smaller and typically have a lot more to offer… longer bloom, prettier flowers, interesting leaf color or texture, compact growth, fall color, or fruit. Here’s just a few that I find exciting.

Thirty years ago many area landscapes were planted with ‘dwarf’ mugo pines. Unfortunately, dwarf is a relative term. If a plant species grows to a height of 15 to 20 feet in height like a mugo pine (Pinus mugo), a dwarf mugo pine (Pinus mugo var mugo) that grows 7 to 8 feet tall qualifies as a dwarf. However, most gardeners were probably thinking a ‘dwarf’ would be much smaller.

Today there are select cultivars of mugo pine that better fit a gardener’s idea of dwarf. The Mops mugo pine grows to a height of 3 feet tall and wide and even smaller are Slowmound and Teeny that both reach a height and width of only 1 to 2 feet.

Forsythia is one of those shrubs that never went out of style because of its bright yellow early spring flowers, but it really was too big for most landscapes, making it a candidate for ugly hedge-type pruning. Today, smaller forsythia are much easier to use in landscapes and don’t require much pruning. In my front landscape I have Gold Tide, a smaller forsythia that reaches a height of 3 feet and a width of 4 feet. Last month it was covered with cheery yellow flowers. What a treat! Even smaller is Show Off™ Sugar Baby, a petite forsythia that reaches a height of only 18 to 30 inches and is covered with flowers in the spring.

The flowering quince is another shrub that joyfully announces spring’s arrival. Most older cultivars are on the large side, reaching heights of 4 to 6 feet, plus they have nasty thorns. I dislike thorny plants and refuse to plant them in my landscape. Proven Winners recently released three flowering quince as part of their Double Take™ Storm series. These twiggy quince grow to three to four feet tall and wide and are both thornless and fruitless. I have one of all three, Orange, Scarlet, and Pink Storm. Their gorgeous intensely colored double flowers resemble a camellia.

One little new shrub I hope to add to my landscape this year is a sweet mockorange called Miniature Snowflake. Mockorange is a very old-fashioned shrub not found in most landscapes today because the older forms are large (12


) with leggy, unkempt growth. Their redeeming feature is the delightfully fragrant white flowers produced in early summer. Miniature Snowflake mockorange is a compact, somewhat rounded shrub that grows 2-3 feet tall and wide. While not remarkable the rest of the season, it produces sweetly scented pretty double white flowers in early summer. I plan to place it near my patio so I can enjoy its fragrance whenever I walk out the door.

Visit your favorite local nurseries to find these and other smaller shrubs that you can easily tuck into your landscape.
Published: 4/20/2012 9:53 AM


written by

Marianne C. Ophardt

WSU Extension Faculty

for the Tri-City Herald, Kennewick, WA

Forget pretty spring flowers, give me red, orange and yellow autumn leaves. Always entranced with the bright fall colors of trees and shrubs, I took a little time the other day to drive around and view the glorious hues of autumn.

One plant that always catches my eye is Burning Bush (Euonymus alatus). It’s bright red fall color is unmistakable. For just that reason, this shrub has been a staple of many landscapes. I can remember a hedge of Burning Bush on my college campus. It was huge. The species form of Burning Bush grows from 15 to 20 feet tall. Of course, most gardeners have planted Compact Burning Bush (Euonymus alatus ‘Compactus’), sometimes misleadingly called “Dwarf Burning Bush.” It is smaller than the species, ONLY growing to a height of 8 to 10 feet.

Because of their still rather large size, Compact Burning Bush shrubs are frequently sheared into ball, oval or square shapes. This is understandable, but unfortunate because the shrub has a very attractive rounded habit with a layered horizontal branching habit. This is lost when sheared to restrain its size.

If you like the color and habit of this shrub like I do, I would recommend looking for cultivars that are even smaller. One of these, ‘Odom’, also known as ‘Little Moses’, only grows to a height of three feet. This little guy has great red fall color, plus it holds onto its leaves a little longer in the fall.

Another diminutive Burning Bush is ‘Rudy Haag’ that grows very slowly to a height of 3 to 4 feet. It’s touted for its small size, dense mounded habit, and pink to red fall color. Within the nursery industry it’s also valued because it’s nearly seedless.

Burning Bush has become invasive in parts of the eastern US. It’s even been banned in Massachusetts and named as an invasive plant in Connecticut. Why the concern? Seeds from the fruit have been spread far and wide in the northeast by birds. “Planted” by birds, the shrubs have spread from landscapes and highway medians to the native forests where they have prospered, displacing native understory shrubs and wildflowers. While the spread of Burning Bush isn’t a worry in our area, the threat of invasive plants forcing out native growth should be of concern to all of us.

Recent research has shown that ’Compactus’ is a prolific seed producer. ‘Compactus’ and ‘Rudy Haag’ produced an average of 1238 and 12 seeds per plant, respectively. This was across a span of three years and over two growing sites. ” With very limited seed production, ‘Rudy Haag’ is much less of an invasive threat.

While sightseeing in the area, I noted many gorgeous trees and shrubs with excellent fall color. There were some spectacular maples along Jadwin in Richland. It was hard to make a definite identification while driving by, but they were most likely red maples or red maple hybrids.

Red maples (Acer rubrum) are well known for their beautiful fall color potential and there are a number of named cultivars. ‘October Glory’ is one very popular red maple cultivar with red to burgundy leaves in the fall. ‘Red Sunset’ tends to develop its orange to red fall color earlier than ‘October Glory’. ‘Autumn Blaze’ is a hybrid of red maple (Acer rubrum) and silver maple (Acer saccharinum). It has amazing fiery orange-red fall color, plus it’s a fast growing shade tree.

There are also other shrubs that can lend various hues of red ,orange, and yellow to the fall landscape. This includes Ninebark (Physocarpus opulifolius), Tiger Eyes Sumac (Rhus typhina ‘Tiger Eyes’), Amur Maple (Acer ginnala), Paperbark Maple (Acer griseum), and Dwarf American Cranberry Bush (Viburnum trilobum ‘Nanum’).

We may not have the spectacular fall color of the Northeast, but if you drive around the Tri-Cities you’ll see some outstanding plants in their fall glory.

Published: 10/24/2009 11:31 AM


written by Marianne C. Ophardt WSU Extension Faculty for the Tri-City Herald, Kennewick, WA Well spring is right around the corner and anxious gardeners are trying to take advantage of the nice days to get some early spring gardening tasks checked off their “to do” lists. Number one on many gardeners

lists is pruning. This is a good time of year to prune fruit trees and ornamental trees and shrubs in the yard. The lack of leaves makes it easier to see what you

re doing, plus you don

t have a bunch of leaves to haul away or chop up for the compost. Once out in the yard, it doesn

t take long to notice that the severe cold temperatures in early January did not treat some broadleaf evergreen shrubs, such as English laurel, holly, euonymus, and photinia, very kindly. These evergreens and semi-evergreens have come through the milder winters of the past few years with little damage, but this year is a different story. Brown leaves are evident on many of these broadleaf evergreens, especially those in more exposed situations or with sunny southwest exposures. Right now, many of these plants are looking like “goners”, but don

t be too quick to pronounce them dead and start pruning severely to remove all the ugly brown leaves. It

s best to check to see if the twigs and branches are still alive. It may only be the leaves that were injured by the cold temperatures. You can check for signs of life by using a pocket knife or a fingernail to carefully scrape off the bark on twigs and branches. They

re alive if you find white or bright green tissue just beneath the bark. Dead twigs and branches will be brown underneath and may have even started to dry and shrivel. If you find dead tissue, keep checking further down on the twig, then branch, then trunk… until you find live tissue. Older wood tends to be less susceptible to cold temperature damage than younger woody tissue. If there is any doubt whether the wood is dead or alive, give it a chance to grow. Many plants that look pretty grim, often recover and start to grow. In late spring you

ll be able to see more easily where dead tissues end and live wood begins. Then you can prune your trees and shrubs to remove damaged tissue. Our string of mild winters came to an end this January, and the broadleaf evergreens aren

t the only landscape plants showing up with significant damage. As I already noted several weeks ago, rose bushes in many parts of our region have sustained quite a bit of cane damage. I checked my roses last week and found that they truly are in sad shape. You can tell if a rose cane is damaged if the “pith” at the center of the cane is tan or brown. Even if the outside of the cane is green, that portion of the cane is not going to make it if the pith is not white. The recommended time to prune roses coincides with the flowering of forsythia, the prominent yellow flowering shrub that blooms in early spring. This is when you lower the overall height of a rose shrub along with reducing the number of canes. You should also remove any very weak or competing canes. However, you don

t need to wait for the forsythia to bloom to remove the dead wood. This can be pruned out at any time. If you have a lot of roses, you might want to start cutting out the obviously dead portions now. Other plants that have apparently taken a hit from the cold winter temperatures are pine trees. Some local residents have been noticing that the needles on their pines are brown and falling off. Most of these trees appeared healthy last summer and fall and only showed signs of a problem after early January. That leads me to suspect that the spell of severe cold temperatures was involved. This is surprising since pines are usually quite hardy. We

ll have to wait until after new growth begins to judge the extent of the injury. Given our sudden hard frost in October and the severe cold in January, I predict that the English or Persian walnuts growing in the region will once again exhibit serious dieback. Last spring, many English walnuts leafed out and then started to die back. At first, several fungus diseases were suspected to be the cause of the dieback. It was later concluded that the problem was primarily due to the sudden October freeze experienced the previous fall. This same weather situation occurred again last fall when we had a hard frost in October before most woody plants were fully prepared for cold temperatures. The same type of damage will probably be evident on the English walnuts again this year, in addition to dieback from fungi that entered dead tissues that were not pruned out last year. I

m sure we

ll be talking more about winter injury in the week to come, but that

s enough for today. Let

s talk about something else. If you have some shrubs or perennials in the landscape that you need to move, now is a good time to transplant them….while they

re still dormant. First prepare the area where you

ll be planting them. If you

re planting them in a landscape bed, till the entire bed and then work peat moss or well-rotted compost into the soil. Have your holes dug and have water ready. Dig up the plant to be moved with as much of the roots as possible. The more roots you cut and destroy, the less the chance of survival. The prepared hole should be as wide and only as deep as the root mass of the plant you

re moving. Place the plant in the prepared hole and situate it so it

s at the same depth that it was growing before. Backfill the hole and then water thoroughly to settle the soil around the roots. Shrubs and trees should be planted so the top of the root system is just below the soil line… no deeper. After watering and filling in with any additional soil needed to compensate for settling, it

s a good idea to mulch with an organic material. Getting plants transplanted this early gives them a chance to start regrowing their roots and become partially established before the leaves and warmer weather start making demands on them. Once the plants start growing, roots are needed to absorb water for the rest of the plant. The later you wait, the more stress the plant experiences and the greater the chance the plant won

t survive. I

ve also noticed that some stores are already offering packaged bare root rose shrubs for sale. While I

d rather see these arrive a little later, they should be purchased and planted now… not left in the warm store or put in the garage waiting for nicer weather. Despite what the directions might say, it

s recommended that you remove the cardboard box from around the roots and then soak the roots for about one to two hours before planting. (Don

t leave it in the water any longer.) When planting roses in our area, local rosarians suggest planting the graft or bud union (the swollen area of the stem near the base of the plant) slightly below (one to two inches) the soil. This protects the graft during our colder winters, such as the one we just experienced when temperatures dropped to well below zero. To plant a bare root rose, place a mound of soil in the center of the planting hole and place the plant on top of the mound and arrange the roots over the cone. Then carefully fill in the soil around the roots, holding the plant so the graft will end up at the right level. Gently firm the soil around the roots and then water the plant thoroughly and add more soil if needed. Check the graft level before you finish. Because our area tends to be windy in the spring, it

s also recommended that you lightly mound soil or mulch at least half way up the new plant to prevent drying of the canes, even if they

ve been coated with wax to help guard against dessication. Once the top buds begin to grow and the young shoots are about two inches in length, you can remove the mound of mulch and soil. Do this very gently, or you may knock off young shoots that have already begun to grow beneath the mulch. Keep a layer of mulch over the roots to retain soil moisture and to protect the bud union. As with other shrubs, you

ll want to keep the soil moderately moist after planting so the roots can grow.

Published: 3/6/2004 2:31 PM


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

I hate to whine, but it has been so-o-o- gray for so-o-o long, it

s a wonder we haven

t all succumbed to overwhelming glumness. While it

s fun to thumb through garden magazines and seed catalogues and plan this year

s garden, even that becomes tiresome after a while. Take heart… spring will be here soon and then the buds on our trees and shrubs will burst forth with their long awaited greenery. While you wait, consider that now is an excellent time to be pruning trees and shrubs.

Late winter is a great time to prune dormant deciduous plants because the leaves are missing and you can see their framework of branches and limbs. An added benefit when you prune at this time of year is that there are no leaves . You only have to dispose of the wood you take off, not the leaves too.

Now let

s talk about why to prune your trees. These are the only reasons that you should prune a tree . In their order of importance:
1. Most important is the removal of any dead, diseased, or damaged branches. If you fail to remove them, disease (especially wood rots) can get started in dead or damaged tissues and spread into healthy wood.
2. You should also remove branches that are a hazard or causing problems. These are branches that might obscure a clear view of oncoming traffic when exiting a driveway or parking lot; that may be damaging a structure; that threaten to decapitate whoever mows the lawn under the tree, or those that interfere with utility lines. (Keep in mind that any pruning that involves utility lines should be done by a professional arborist. Never attempt it yourself.)
3. It

s also important to prune young trees with structural problems to avoid bigger problems in the future. If there are two competing central leaders, one should be removed. If there are bad crotch or branch angles… ones less that 45 degrees from the main trunk… pruning is warranted. If you leave these bad branching angles, there is a good chance the tree will split or one of the branches may break off the tree when the tree grows and the branches get larger and heavier.
4.Least important is pruning your tree simply for aesthetics, to create the form or shape you want. However, if you purchase a young tree that is asymmetrical with many more main branches on one side than another, you should prune out branches spaced too closely together or ones rubbing against each other.

There are some reasons people prune that aren

t valid.
1. It

s an act of futility to try and keep a large tree small with pruning. Large and small trees are that way because of their genes. Their genes tell them what shape and how big and they should grow. Don

t try to fight it with pruning. It

s better to plant a small tree that won

t outgrow its space. Of course, sometimes you buy a property where large trees have already been planted. Periodic, selective pruning can be a way to temporarily reduce the size of a tree, but it will still try to grow up to its predetermined mature size. Keep in mind pruning large trees is best left to professionals who have the equipment to safely prune large trees.

2. Don

t prune the top of the tree because it

s become so big and you

re afraid it will blow over. If a tree is healthy and has a well developed root system, it should be able to withstand heavy winds. Trees that blow over in wind storms usually have very shallow root systems or compromised root systems. Shallow root systems can be due to high water tables, shallow watering, excessive watering, compacted soils, or a limited volume of soil available for development of a root system. Compromised root systems are those where trenching or other activities have severed large roots; where excessive soil moisture has resulted in root rot; or where the tree was planted with kinked and girdling roots that prevented the development of a stable root system.

In the past, arborists have recommended that a tree

s crown be “thinned” to allow for air flow and decrease wind resistance where blow-over is a legitimate concern on larger trees with questionable root systems, especially conifers. Interestingly, new research is indicating that thinning may actually increase a tree

s resistance to the wind and make it more prone to blow-over.


This is a good time of year to stand back and look at your trees, to see if they do need pruning. Most ornamental trees, large and small, don

t require regular pruning , but if your tree needs any corrective pruning… now is a good time to look for it and take action.


s also a good time of year to look at the results of past pruning cuts. The results of past topping and stub cutting is very evident. Topping and stub cuts result in lots of sprout growth that tend to grow straight up and ruin the natural shape and beauty of a tree. The sprouts come from adventitious buds and are weekly attached to the trunk. As they grow, they become bigger and heavier and more likely to break off in the wind. You should also note that stub cuts don

t “heal

over, leaving an open door for wood rot fungi to get started.

If the topping activity was in the last several years, you might also notice how rapidly these sprouts grow. Usually, the growth that results from topping is very vigorous, as the tree is still trying to grow up to its mature size. If a tree must be pruned to reduce its size, selective thinning cuts will maintain the shape of the tree and minimize rapid regrowth in contrast to a tree

s response to topping.

While you have a clear view check your trees out for other problems. Look for signs of boring insects. See if you have any broken branches, splits in the trunk, or bark injuries. Look for evidence of wood rot in the trunk … trees with substantial amounts of internal wood rot are dangerous hazards.

So while it may be too early to do many things out in the garden, it is a good time to check out your trees and do any needed pruning. Call an ISA (International Society of Arboriculture) certified arborist if the trees are larger than you can safely handle. Next time, I

ll talk about pruning shrubs. In contrast to trees, many deciduous shrubs, especially the flowering ones, need regular pruning to keep them attractive and contributing to the beauty of the landscape.

Pruning Note: Conifers, evergreens with needles and cones, should not be pruned for any reason other than to remove damaged limbs or to remove branches that create a problem.

Published: 2/21/2004 2:32 PM


written by

Marianne C. Ophardt

WSU Extension Faculty

for the Tri-City Herald, Kennewick, WA

Why spend so much time talking about planting trees and shrubs? It’s because they’re one of the most important investments you can make in creating an attractive landscape that will enhance your home and increase your property value as they grow. Making sure trees and shrubs survive and thrive should be your goal when you’re planting them.


There seems to be no general consensus among experts regarding how to fertilize newly planted trees and shrubs except for a caveat against adding fertilizer to the backfill soil. This warning is because of the salts contained in fertilizers and the tendency of gardeners to apply too much of a good thing.

Our local soils are usually low in available nitrogen and organic matter. Moderate fertilization at planting time will help get the plant off to a good start. I would suggest sprinkling fertilizer on the top of the soil over the entire planting area before applying any mulch. Ammonium sulfate (21-0-0) is both acidifying and provides quick-release nitrogen. It can be applied at the rate of 0.5 pounds per 100 square feet of planting area. If you have sandy soil, consider using a fertilizer containing some slow-release nitrogen. A coated granular slow-release fertilizer or slow-release pellets can be safely placed in the planting hole at planting time.

Once your tree or shrub becomes established and if it’s located in or adjacent to a lawn area, there will probably be adequate fertilizer reaching the roots if you regularly fertilize your lawn.


So let’s briefly review our lessons over the last three weeks on the best way to plant trees and shrubs:

1. Dig the hole only as deep as the root ball, and three to five times as wide as the roots.

2. Remove all burlap and any other coverings around the root ball once the plant is in place in the hole. Make sure the root collar is at grade or slightly above grade.

3. Loosen the roots of plants grown in containers. Remove circling and kinked roots that can’t be straightened.

4. Backfill the hole with native soil. No amendments are needed. Water thoroughly to settle the soil around the roots. Don’t stomp on the roots to firm the soil.

5. Avoid staking the tree.

6. Mulch the planting area with a 4-inch layer of bark or wood chips.

7. Keep the soil moderately moist (not wet) for the first two growing seasons. To check the soil moisture in the root ball, use a trowel or soil probe to dig down and see how moist the soil actually is in the root ball.


Our recent spate of cold weather has frustrated gardeners who wanted to get an early start on the season. Here are some possible repercussions of the downright frosty weather that hit many parts of our region:

– Damage to fruit tree blossoms will result in a decreased or possible a lack of a fruit, especially on early blooming trees, such as cherry, peaches, and apricots. However, the good news is that if the frost didn’t kill all the blooms, the lighter crop on the tree will have larger fruit due to this natural “thinning” performed by the frost.

– Alas, in some areas the frost resulted in an early finish to the bloom of some flowering trees and shrubs, such as star magnolia.

– The tender newly emerging leaves of some landscape trees and shrubs may have sustained frost injury. While generally not critical to the tree’s health, the damage may be noticed later as holes in the leaves once they reach maturity. This is because the frost may have damaged groups of cells on the leaf. These dead cells don’t expand along with the uninjured leaf tissue, causing holes, tears, tattering, and distorted growth.

– Even if you protected warm-season plants already in the garden from frost, they may have sustained some chilling injury and will be slow to take off once warm weather arrives to stay. Warm-season vegetable crops (tomatoes, peppers, eggplant, squash, melons, and cucumbers) sustain chilling injury when exposed to temperatures below 50 degrees Fahrenheit for extended periods of time. The more sustained the chilling, the greater the injury. As a result plants may have stunted growth and be slow to establish, lagging in growth behind plants placed in the garden later after the cool weather.

Published: 4/26/2008 2:01 PM


written by

Marianne C. Ophardt

WSU Extension Faculty

for the Tri-City Herald, Kennewick, WA

Because of the increasing frequency of root defects and planting problems that we’ve already discussed, a growing number of horticultural experts around the country are recommending taking more drastic steps when planting trees and shrubs. They propose removing all the soil or potting mixture from the roots of both container grown and balled-and-burlapped plants. This is done using a water bath and hose to “wash” the roots. The process allows you to note and correct any girdling and kinked roots that weren’t visible with the soil covering the roots. You also avoid problems that occur because of extreme differences in texture between the root ball and the backfill soils, such as balled-and-burlapped trees with heavy clay root balls planted in sandy soil. In addition, it’s easy to tell where the root collar is located, facilitating planting at the correct depth.

After washing all the soil off the roots, the trees and shrubs are then planted as if they were bare-root plants. It’s important to emphasize that this method of planting is drastic and aggressive. If done properly when the plants are young and still dormant… and during the cool weather of early spring, plants will survive if given the proper follow-up care. The roots must be kept cool and moist during the process. It’s critical not to allow the roots to dry out during the washing and planting process.

While these drastic methods of tree planting tend to upset traditional retail nurseries and negate any plant warrantees given to buyers, it may be the only way to insure that a tree or shrub will have a long and happy life. The increased mechanization and mass production by wholesale growing nurseries has led to the frequent occurrence of root problems and root defects. University researchers have found that when done properly, the benefits of these drastic planting methods outweigh the negatives.


In most home landscape situations staking trees is not necessary or recommended. Research over the years has proven that trees do better if they’re not staked. Trees establish more quickly, developing more roots and thicker, stronger trunks without staking. Scientists believe that the swaying motion of the tree trunk stimulates the production of plant growth regulators that promote trunk and root growth.

However, in extremely windy situations a tree may need to be staked. Trees may also require staking in public situations in order to protect the tree from vandalism or mower injury. This is best accomplished using two stakes secured to the tree using three inch wide horizontal straps of webbing that are then attached to the stakes using heavy gauge wire. Never, never secure a tree to a stake using a hard material such as wire (even if cushioned by a section of garden hose) or plastic that can damage the trunk. The straps should be secured on the lower half of the trunk to allow for as much trunk movement as possible. Staking should not be left on for more than one year.

NEXT WEEK: Next week we’ll talk about fertilizing at planting, watering, and we’ll review the steps we’ve covered in planting trees and shrubs correctly.

Published: 4/19/2008 2:02 PM


written by

Marianne C. Ophardt

WSU Extension Faculty

for the Tri-City Herald, Kennewick, WA

Last week I talked about common tree and shrub planting problems. I focused on digging the right size hole, planting at the right level, and mulching. This week, let’s talk about why your tree or shrub may be doomed even if you do everything you can to plant it right. Root problems and the resulting plant failures are an increasing challenge for anyone who plants a tree or shrub and wants to see them thrive. “Root problems” is a generic term for several specific problems that can happen long before the plant gets to the local garden center or your yard. Lets take a look at each.

DENSE ROOT MASSES: Trees and shrubs and even annual flowers, perennial flower and vegetable transplants often develop dense masses of fibrous roots when grown in containers, especially if the plants have been left in the containers too long and become “root-bound.” If planted in the ground without disturbing the tightly packed mass of potting medium and roots, the roots of container grown plants often fail to grow out into the surrounding soil. This limits the plants’ access to water and soil nutrients available in the surrounding soil, leading to plant stress and a failure to thrive.

When you pop a plant out of a pot, you need to encourage the roots to leave the molded and possibly root-bound mass. If not too dense, you can use your fingertips to gently loosen the potting medium and tease the roots out of the mass. Watering the plant thoroughly before removing it from the pot will make this process easier.

If the mass is too thick for teasing easily with your fingers, use a sharp knife to make six to eight shallow vertical cuts from the top of the root mass to the bottom, cutting through any woody circling roots. Then use your fingers to loosen roots starting at the base and trying to spread them outwards away from the mass.

If the roots are so tightly knitted together that they can’t be loosened, it’s been generally accepted that it’s still important to slice into root ball as deeply as possible to encourage root growth out of the root ball. However, new university research indicates that this usually doesn’t result in roots growing outwards from the root mass. Experts at the University of Florida now recommend slicing off the entire outer inch of both the sides and bottom of root-bound masses. The experts indicate that roots should be cut at the point just before they dive deeper into the soil near the sides of the container.

This is drastic but if the root-bound plants don’t develop roots out into the soil, they’re doomed. However, I would advise against purchasing plants that are so tightly root-bound. If you do have a severely root-bound plant and decide to follow these new recommendations, you’ll want to do your planting early in the spring, long before hot weather is imminent.


Kinked and girdling roots are also common root problems that sentence a plant to eventual failure. While not an extremely technical term, it’s important to note that “girdling roots” are roots that partly or completely encircle a plant at its base, literally choking it to death by constricting the trunk or root collar tissues and preventing the movement of water and nutrients. This happens over time as the girdling roots grow in girth.

Kinked roots are a bit different. They’re roots that are sharply bent one or more times. Similar to a kink in a hose, they restrict the movement of water and nutrients and prevent the development of a well structured root system. When planting trees or shrubs with circling or girdling roots, it’s recommended that you straighten the roots if possible. If not prune them off, along with any kinked roots.

Next week will be the final installment in this “series” of columns about tree and shrub planting. We’ll discuss the drastic planting methods being recommended by horticulture experts to avoid the root problems covered last week and today, in addition we’ll also talk about staking and fertilizing.

By the way, did you know this is Arbor Month? Go “green” and help the environment by planting a tree or shrub… the right way.

Published: 4/12/2008 2:02 PM

« Older Posts



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

WSU Extension, Franklin County, 1016 North 4th Ave, Pasco, WA 99301-3706, 509-545-3511, Contact Us
© 2017 Washington State University | Accessibility | Policies | Copyright | Log in