On April 1, the Richland Riverside Rotary Club and the WSU Master Gardeners celebrated 100 years of Rotary by planting 101 arborvitae.

They took on this monumental task in the Formal Garden being constructed in the Master Gardener Demonstration Garden in Kennewick. Not knowing how miserably wet and cold it would be, they picked that morning to plant these shrubs donated to the garden by Riverside Rotary. While it wasn't optimal weather for their personal comfort, it was a great time for planting trees and shrubs.

Early spring, while plants are still dormant and before new growth begins, is the best time to plant trees, shrubs and perennial plants in our region. That's because the plants can start to grow new roots before they're faced with hot weather and high demands for water. When trees and shrubs are planted during late spring or summer, they often become drought stressed even if there is plenty of water available. That's because they haven't had time to grow new roots to absorb as much water as they'll need during the summer.

Thanks to the intrepid master gardeners and Rotary members, the 101 arborvitae have a good chance of establishing well and flourishing in the garden before hot summer weather arrives. However, timing isn't the only key to planting success. The correct planting procedures are just as important as the time of planting. Let's review the best way to plant trees and shrubs to insure success.

-- The hole: It often makes folks feel good to dig a nice deep hole when planting a tree or shrub, but it's the width of the hole that's most important. Scientists have found that most woody plants don't have deep "tap" roots. The majority of roots absorbing water and nutrients are located in the top 12 to 18 inches of soil, where they can get air and water.

A planting hole should only be as deep as the plant's root ball. When you dig the hole deeper, the plant often settles after planting and ends up being planted too deep. The top roots radiating out from the trunk should be just below the soil surface. Instead of deeper, holes should be dug wider, at least twice as wide as the height of root ball. By digging a wide hole, the soil is loosened, making it easier for the roots to grow.

-- The root ball: If the plant is "balled and burlapped" with a root ball surrounded by soil and wrapped in burlap, the burlap should be removed. While old-time gardeners and nurserymen may tell you that you shouldn't remove the burlap for any reason, horticulturists strongly recommend its removal. One reason for this is that burlap doesn't decay as quickly as once thought, especially in our dry climate. Plus, much of today's burlap is treated with copper, giving it a green tint. This copper treatment is intended to slow the decay of the burlap. Another important reason to remove the burlap is to look for any root problems, such as circling, girdling or kinked roots or additional twine and burlap that might be hidden by the outer burlap.

Researchers also recommend removing the soil around the root balls of balled and burlapped plants. This way you have a much better chance of finding serious root system defects that may be hidden by the soil. You also want to remove the soil because it's often a heavy clay that's very different in texture from soil in local landscapes. This big difference in texture impedes water movement and discourages root growth.

Linda Chalker Scott, WSU Extension horticulturist, recommends these steps when planting a "B&B," or balled and burlapped tree or shrub:

1. Remove all wire baskets, twine and burlap from the root ball. Do this on top of a tarp to make it easier to transport the root ball remnants elsewhere.

2. Remove the soil from around the root ball, using a water bath or hose. Use your fingers to work out clumps of clay from between the roots.

3. Look for and prune defects in the freshly bared root system. Be sure to keep the roots moist during the procedure. Work in the shade or on a cool, cloudy day if possible.

4. Dig the planting hole, making it only as deep as the root system and at least twice as wide. The hole will resemble a shallow bowl, not a deep pit. If necessary, mound the soil in the bottom of the hole to help support the tree when planting. Arrange the roots radially in the hole.

5. Backfill with native soil -- no soil amendments should be added to the hole.

6. Water in thoroughly, sticking the hose right into the loose dirt. Once all air pockets are out, let the water settle and then use excess soil to bring the soil to the correct level. Use your hands, not your feet, to firm the soil around the base of the tree.

7. Apply an appropriate fertilizer. Mulch the entire planting hole with at least four inches of organic mulch, keeping an open buffer zone between the trunk and the mulch. If needed, stake the tree low and loose with three stakes.

Chalker Scott admits that, "This method is radically different from historically accepted practices. Yet recent and ongoing research demonstrates that bare-rooting B&B trees leads to substantial increases in tree establishment and survival. Investing the time to prepare and install trees properly will pay future dividends of reduced maintenance and mortality for the lifetime of your landscape." Following these guidelines will help ensure tree and shrub survival in your landscape.

* Marianne C. Ophardt is a horticulturist for the Washington State University Cooperative Extension Office in Benton County.