It is quite obvious that to plant something, the container must be completely removed. However, removal of a box from a large boxed tree would leave the heavy root system very susceptible to damage as it is moved into the planting hole.

It is best to place a boxed tree into the planting hole with the box intact. After cutting the steel bands that hold the box together, the four sides of the box can be disassembled and removed from the root ball. The bottom of the box can be left under the tree and will eventually rot away--instead of removing the plant from the container, the container is removed from the plant.

Scoring the root-ball to sever circling roots is a standard procedure that is important to many plants, but can be damaging to others. Plants with very sensitive roots, such as pines or eucalypti, are so distressed by this procedure that only the few obvious circling roots should be cut individually. Because these trees are also easily damaged by circling roots, they are not worth planting if they have more than a few circling roots that need to be severed.

Many plants with very fibrous roots likewise do not need to be scored because they lack long thick roots that might circle within a can. For example, overgrown rhododendrons with densely congested root systems typically have only a few, if any, circling roots. Scoring would probably be harmless, but would not be necessary. Bougainvillea do not need scoring either, but have such delicate roots that they would likely be damaged by scoring.

It is commonly believed that a planting hole should be twice as large as the root-ball to be planted into it. This rule is unfortunately somewhat vague. A planting hole that is twice the "width" of a root-ball is rather generous, but appropriate for smaller plants, such as those in 1- and 5-gallon cans. The depth should, however, be slightly less than the depth of the root-ball, so that the ball is held slightly above grade (no more than an inch for these smaller sizes). If the hole is deeper and back-filled with loose soil, new plants will sink as lower backfill settles.

Planting holes that are twice the width of larger trees, such as boxed trees, are excessive. If a 4-foot-wide box is planted into an eight-foot-wide hole, the loosened backfill will be 2-feet-wide all the way around the root-ball. This is much more than the roots need to make the transition from the growing medium ("soil" within the box) into the surrounding soil.

Soil amendments, such as redwood soil conditioner, ease this transition. As much as a third per volume can be added to the densest clay soils. Very rich or well-drained soils need considerably less. Amendments are added to encourage roots to grow out of growing media, into the surrounding soil mixed with amendments, and then beyond into surrounding soil without amendments. If surrounding soil is already attractive to roots, no such encouragement is needed.

Once installed, a new plant should be soaked so that soil settles around the root-ball. Until roots disperse, new plants will need to be watered frequently. Overgrown plants with abundant foliage consume more moisture, so will of course need more water.

Flower of the Week:
Sweet-pea shrub

Sweet-pea shrub, Polygala dalmaisiana, blooms in only one color, but it is striking. The pinkish-purple "pea-like" flowers look almost artificial against their light bluish evergreen foliage. Although not profuse, flowers bloom almost continually during warm weather.

Both flowers and leaves are about an inch long. Mature plants may be as high as 4 feet and as wide as 5 feet. Leaves drop from interior stems, leaving them bare. Occasional shearing encourages bushier outer growth, which conceals interior stems. Sweet-pea shrub appreciates regular irrigation and full sun. It will tolerate light shade.

Horticulturist Tony Tomeo can be contacted at 408.358.2574 or at LGHORTICULTURE@aol.com.