Prune to keep ornamental shrubs healthy

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As winter moves toward spring, pruning jumps to the top of the gardening “to-do” list. Pruning keeps ornamental shrubs healthy by removing dead, dying and diseased wood and encourages the natural and sturdy growth of the plant.

“Pruning is one of the most important tasks to keep shrubs and bushes healthy,” explained Ross Penhallegon, horticulturalist and pruning expert with the Oregon State University Extension Service. “Yet pruning often gets neglected or forgotten.”
Basic pruning guidelines deal with the many sizes, shapes and growth forms of ornamental shrubs. Most gardeners should do some pruning each spring and/or summer if they have spring or summer bloomers, Penhallegon said. Shrubs that bloom in the early spring, such as forsythia, rhododendrons and azaleas, should be pruned when they finish blooming. Then they have the rest of the growing season to form new branches and flower buds.

Shrubs that flower in the summer and fall are blooming on this year’s growth. They should be pruned early in the dormant period or very early spring so there’s plenty of time for new growth to form and bloom.
“Sometimes it’s worth it to prune out of season and sacrifice a year of blooms,” Penhallegon said. This is the case when the bush is overgrown, has gangly branches or has been neglected for years. This type of pruning should be done in the dormant or winter time.
Light pruning can be done in the summer, when it’s easy to spot dead, dying, diseased, or weak branches with few leaves. Pruning in the winter allows you to see how the branches grow in relation to one another. Branches growing toward the center of the plant or crossing or rubbing other branches are good candidates for removal. This kind of maintenance pruning in itself reduces the size of the plant if it is too large.
If you prune regularly every year, you never need to prune too severely. Yearly pruning keeps the plant in good condition with new and old branches and some in between. If the plant grows too tall or large from lack of pruning, it can overwhelm neighboring plants and surroundings.
“A little pruning each year helps to keep the plant in bounds, keeps it healthy, allows good light penetration and encourages blooms every year,” Penhallegon said.

Shrubs can be pruned drastically if they get out of hand and need rejuvenation. Multi-stemmed species such as spirea and forsythia can be heavily pruned by removing the older stems or branches, lowering the height of the plant. Rhodies and azaleas can be heavily pruned to 12-14 inches or just above buds that are on the lower part of the plant.

An overgrown shrub with a single lead or trunk growth form needing rejuvenation should be gradually pruned down or brought under control to maintain the natural form of the plant. Don’t be tempted to shear off the top of this kind of plant. Always cut back to a good side branch. Shearing may be faster, but it will produce a leggy plant with brushy growth at the stem ends. Each cut will often produce two more branches. Some large shrubs, like laurel, will sprout from bare wood even when they’re cut back nearly to the ground. Evergreen shrubs, both broad-leafed and needled, should not be pruned back to bare wood.

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About Garden News from OSU Extension Service: The Extension Service Gardening web page, http://extension.oregonstate.edu/community/gardening, links to a broad spectrum of information on Oregon gardening, such as tips, monthly calendars, how-to publications, audio programs, the Master Gardener program and “Northwest Gardeners e-News.”

By Judy Scott, O.S.U., Corvallis Ore
Source: Ross Penhallegon, O.S.U.Extension Service

AGC Book Club: To the Woods

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To the Woods: Sinking Roots, Living Lightly,
and Finding True Home
by Evelyn Searle Hess

To the Woods is the true story of Evelyn Searle Hess & her husband, David, who, in their late fifties, walked away from the world of modern conveniences to live on twenty acres of wild land in the foothills of Oregon’s coast range mountains not far west from Eugene. Ms. Hess describes their day-to-day struggles, failures, and discoveries with lush descriptions of their surroundings and its rhythms of life. While developing a wild plant nursery & planning their new home, she writes about learning and living with the joys of their natural environment. It tracks the natural history of place through the seasons, and living life in concert with nature. Through her thoughtful prose, she wrestles with issues like human impact on the ecology of our planet.

Written By Viki Ashford

Subshrubs

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Subshrubs have the unique characteristics of both herbaceous and woody plants. Their bases are woody but they produce new herbaceous growth during the primary growing season. Many herbs fall into the subshrub category, such as:

SunsetHyssop (Agastache rupestris)
Form: Vase shaped plant maturing to 2 feet high by 1.5 feet wide
Exposure: Full sun
Color: Flowers vibrant pink, purple and orange
Bloom Time: Long bloom season summer to fall
Attributes: Fragrant, Attracts Bees & Butterflies, Ornamental, Medicinal, Culinary
USDA Hardiness Zones: 4b-9


English Lavender (Lavandula angustifolia)
Form: Upright clumping growth habit, 1.5 feet tall by 2 feet wide
Exposure: Plant in full sun to partial sun in evenly moist and rich soil
Color: Green-gray to green–purple foliage in the summer, silver-green to gray-bronzed in the winter. Flowers blue-purple, lavender, violet-blue, or white-pink, depending upon cultivar Bloom Time: varies with cultivar
Attributes: Semi- evergreen, Fragrant, Ornamental, Medicinal, Culinary
USDA Hardiness Zones: 5-9

Garden Sage (Salvia officinalis)
Form: Woody Stems, 3′ tall and wide,
short lived, needs replacing every 3- 4 years
Exposure: Full Sun
 Color: Grayish foliage – Flowers blue to purplish   Bloom Time: May- July

Attributes: Water Conserving Evergreen, Fragrant, Ornamental, Medicinal, Culinary
USDA Hardiness Zones: 5-9

Russian Sage (Perovskia atriplicifolia)
Form: Woody base with upright stems 3 to 4.5 feet tall
Exposure: Full sun, hardy, drought tolerant
Color: Grayish-white stems, silver-gray foliage with small tubular deep blue or lavender flowers
Bloom Time: July – September
Attributes: Pungent fragrance, attracts butterflies, Ornamental, Culinary, Medicinal, deer-resistant
USDA Hardiness Zones: 3-9

Deerwood (Lotus scoparius) (California Broom)
Form: Woody base with arching airy branches, grows to 3 feet
Exposure: Full sun to partial shade
Color: Flowers begin as yellow, turning to orange
Bloom Time: April-June
Attributes: California native, feeds numerous wildlife: hummingbirds, bees, butterflies and deer. Bees relish this plant! Nitrogen fixing capabilities
USDA Hardiness Zones: 6-10

Wormwood (Artemisia absinthium)
Form: Tall straight clusters of silvery-green branches, foliage spirally arranged, grows 3 feet tall by 2 feet wide.
Exposure: Full sun to partial shade, drought tolerant
Color: Greenish-grey foliage clad with silky-silvery “hairs”, small yellow tubular flowers
Bloom Time: June-October
Attributes: Companion plant to suppress weeds – roots secretes substances which inhibit the growth of surrounding plants. Ornamental, Culinary, Medicinal
USDA Hardiness Zones: 4-9

Pruning Subshrubs
Subshrubs are not pruned like softer herbaceous herbs, such as germander, marjoram, oregano, and winter savory, or even other woody plants. Subshrubs are never pruned during the cool fluctuating temperatures of fall and winter and you never cut them to the ground. Subshrubs should be pruned in early spring once signs of new growth appear and then only to remove dead and broken wood. In some cases, pruning can wait until after the first bloom, but technically you should avoid pruning subshrubs because doing so could be harmful to the plant.

by Carlotta Lucas

Happy Soil

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Happy Soil
by Denny Morelli
(Notes from a recent talk at Medford Garden Club)

You can’t have good results in your garden if you don’t start with good soil. Top soils are made up of different components including plant and animal residue, moisture, air space and live soil dwelling organisms.

The best thing you can do for your garden is compost, compost and more compost.

Organic content provides food for growing plants, food for bacteria, fungi, earthworms and other beneficial organisms. A total organic content should be at least 6% of the top 4” – 6 “of top soil. It also provides a reservoir for moisture. Organic content also provides temperature stability and weed control.

This water reservoir prevents the tendency of over watering in the summer and the leaching out nutrients in rainy weather. Over watering can be a serious problem as it flushes out nutrients and increases pollution levels in our streams.

The timing and rate of releasing nutrients is important. Organic material helps to control the amount of fertilizer available at any given time. Air space created by the channels made by various organisms provides space for oxygen, moisture and plant roots. Do not rototill. Tilling the soil collapses this delicate structure. It is better to put a layer of 2” – 4” of compost on top early in the spring to let the nutrients sink in.

One problem in planting is that plants are usually planted too deep. Dig the hole, add some compost and plant the plant so it is higher than ground level, creating a small rounded berm. In time it will sink to the level of the ground.

Be careful where you buy compost. Most box store compost may be over a year old and have little nutrients left. Denny’s commercial formula is 40% forest material, including rotted wood, leave, moss and humus; 50% pasture material, including shredded alfalfa, grass and cover crops; 10% dairy goat & chicken manure; and nutrient supplements e.g. seed meal, kelp meal, high protein livestock feed, goat mils and trace elements. Do not use walnut leaves for mulch.

Fertilizers for home gardeners include fish emulsion, which works very fast but needs to be applied often; and Dr Earth, which takes a month to do any good. Be sure to look at the label; a lot of compost has too much magnesium. In the heat of the summer a layer of alfalfa, purchased at a feed store, protects the ground. Denny sells his compost from his farm. Read more here: http://www.ccountry.net/~compost/

Other good sources of compost are Hilton Landscape Central Point and the Grange Coop, who has an excellent compost called Green Planet Compost.

by Emilie Vest

Wildfire: Reducing Risk

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Before summer, homeowners should remove fire hazards and reduce fuel from around their homes. The City of Ashland Oregon is currently helping homeowners with this task by offering grants to city residents to modify and/or remove fire-hazard vegetation near their homes. To participate, residents must first obtain a Wildfire Safety Home Assessment, this assessment includes site-specific recommendations for creating a defensible space around a structure. Read more here: Ashland- Oregon Wildfire News

Planting fire resistant plants around your house may reduce your fire risk during a wildfire, so the OSU Extension Service has provided a list of fire resistant plants for Oregon homeowners. Read OSU’s plant list here: Fire Resistant Plants for Home Landscapes

Below are a few of the plants you will find on their list:

Penstemon
species

Stachys byzantina
Lamb’s Ear

Philadelphus coronarius
Mock Orange

Pachistima myositis
Oregon Boxwood

Spring: Fertilizing Trees & Shrubs

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Spring is a good time to fertilize young trees and shrubs
By Judy Scott, judy.scott@oregonstate.edu
Source: Ross Penhallegon, ross.penhallegon@oregonstate.edu

CORVALLIS, Ore. – Trees and shrubs often are forgotten when it comes time to fertilize the yard in the spring. Young trees, especially those with a trunk diameter of less than six inches, can benefit from regular applications of fertilizer.

“When young trees soak up nitrogen fertilizer, they grow quickly, develop a dense canopy and stay green into the fall,” said Ross Penhallegon, horticulturist with the Oregon State University Extension Service. “It might not be necessary, however, to fertilize large, established trees or shrubs in or near lawns or groundcovers that are fertilized regularly.”

Tree root systems extend for a long distance and they absorb nutrients when the area around them is fertilized. Additionally, as trees mature, their roots develop associations with fungi called mycorrhizae. These beneficial fungi help the tree utilize minerals and elements in the soil.

Before you fertilize, take a look at your trees and ask these questions to help you decide if your trees need additional nutrients:

  • How much annual growth do you see? Most young trees average about 12 to 18 inches of new shoot growth each year; older trees have less.
  • Is your tree growing less than expected?
  • Has the color, size or amount of foliage changed over the past few years?
  • Has the tree recently had disease or insect problems?

If you answered yes to any of these questions, the tree might benefit from fertilization.

  • Another way to determine fertilizer needs is to do a soil test.

“The best time to fertilize is in the spring,” Penhallegon said. “If you fertilize in the fall, you run the risk of shocking the plant into becoming metabolically active right when cold weather hits.” Plus, a lot of the fertilizer will leach into the groundwater due to the excessive rain.

Most woody plants begin the new year’s growth with elements stored from the year before. An application of fertilizer in the spring gives an additional boost to this new growth.

Garden references vary about how much fertilizer to apply to trees and shrubs. Penhallegon has a general rule for fertilizing trees and shrubs – use 1/4 to 1/2 pound of nitrogen per inch of diameter for trees six inches or more in diameter at breast height. Use 1/4-pound actual nitrogen per inch on smaller trees. This is roughly two to four pounds of complete fertilizer per inch diameter on the larger trees and half that dosage on smaller trees. In most cases use the lesser amount.

“As time goes on, you will be able to tell by the condition of tree or shrub, whether or not it needs more fertilizer,” Penhallegon said. “Typically, healthy trees and shrubs have 12 to 18 inches of branch growth per year. Their leaf color should be dark green, with lighter green on new growth.”

Apply the fertilizer along the drip line of the tree, the area with the majority of the roots. If the fertilizer is applied to the soil surface only, much can be washed away or will not filter into the soil to the root zone. Water the fertilizer or allow the rain to keep the fertilizer from washing away.

For quicker absorption, use a punch or probe to make holes 12 to 18 inches deep, and then fill the holes with fertilizer. Then, be sure to water deeply.

Another way to fertilize is to “pepper” the ground with fertilizer as you walk around the drip-line of the tree. This method should also provide an adequate amount of fertilizer. Apply fertilizer in this manner right before it rains, so it will be washed into the root zone. Or water the fertilized area for an hour after application.

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This article is online at: http://bit.ly/OSU_Gardening1534

For more information, see the two-page publication “Fertilizing Shade and Ornamental Trees” at http://bit.ly/OSUESfs103 or visit OSU Extension on-line publications and video catalog at http://extension.oregonstate.edu/catalog. The catalog shows which publications are available online and which can be ordered as printed publications.