Background

Landscape architects commonly refer to shrubs as "the backbone of the garden." They can provide shelter for other garden plants, offer privacy for humans, block unpleasant views, screen out roadside noise and serve as an effective barrier to unwanted foot traffic of both two and four-legged origin. Shrubs can be used to help soften the transition between the lawn and home, to hide exposed foundations, to border (and visually organize) different sections of the garden, to provide contrast to brightly colored flowering plants or to add a dash of cheerful greenery to an otherwise barren winter landscape. Best of all, once established, the majority of these hardy, self-reliant woody ornamental plants seldom require more from us than a late fall watering and some periodic pruning and shaping to survive.

How to Care for Shrubs

Planting.  New shrubs like to be planted in spring or fall, and most prefer loose, fertile soil that drains well and has a modestly acidic to neutral pH in the 6.0 to 7.0 range. Deciduous shrubs should be planted when dormant, usually in early spring before new leaves emerge or in late fall after old leaves have been shed. To plant container grown shrubs, just follow these simple steps:

• If the soil of the planting site is overly acidic or alkaline for the type of shrub you've selected, amend it beforehand by adding lime (to raise the pH of acidic soil) or elemental sulfur (to lower the pH of alkaline soil) as necessary.
• Dig a hole twice as wide and slightly less deep as the rootball of the shrub, angling the walls of the hole outward toward the top and making sure the bottom of the hole is firm, yet drains well.
• Remove the shrub from its container. Inspect the rootball and snip off or pull away any roots that are circled, matted or tangled. Also, trim any dangling root ends to prevent them from becoming bent or tangled when the rootball is placed in the hole.
• Place the shrub in the planting hole so that it is centered in the space and stands straight and tall. The top of the rootball should be slightly above the level of the surrounding soil. If it is at or below that level, add some soil to the bottom of the hole and reposition the rootball.
• Improve the backfill soil you've dug from the hole by amending with rich, organic materials such as compost or pre-packaged garden soils and planting mixes. If planting in spring, add a complete, slow release fertilizer to the backfill soil. Backfill the planting hole to the level of the top of the rootball, sloping the soil away from the trunk to the level of the surrounding soil.
• Create a 2-4 inch high lip around the perimeter of the planting hole to act as a catch basin for water.
• Fill the collection basin with water until the ground is loose and muddy in order to eliminate air pockets. If the shrub needs to be re-positioned slightly, do so at this time by gently jiggling it into place.
• Mulch around the young shrub to retain moisture and prevent encroachment by weeds and invasive lawn grasses. Also, water frequently until the shrub has become well established, especially if the foliage shows signs of withering or curling during the heat of the day.

Feeding. Regular feeding can not only keep your shrubs flowering and growing vigorously, but specially formulated plant foods can correct pH imbalances that can lead to nutrient deficiencies. Apply the appropriate formula of slow-release plant food at planting time and periodically through the growing season. If you don't use a slow-release plant food,  feed weekly with all-purpose water soluble plant food. To feed large areas, use a hose-end feeder.

For flowering shrubs, switch about 4 weeks before the flowering period to a high-phosphorus water soluble plant food specially formulated for flower bud development.

For acid-loving shrubs like azaleas, rhododendrons, camellias, boxwood, dogwoods, holly and others, use an acidifying water soluble plant food.

Pruning. Pruning is a complex subject, and difficult to deal with in a generic overview, since different shrubs have widely ranging prunings requirements. Most shrubs will need to be pruned regularly for a number of reasons. Dead, diseased or damaged limbs of any tree or shrub should be pruned immediately at any time of year to protect from additional insect or disease damage.

Beyond that, many shrubs may require little or no pruning, especially if the mature size was considered when selecting and placing the plant. Others, though, benefit from occasional pruning, while still others will require a regular program of maintenance pruning. It's best to ask your nursery professional at the time of purchase what kind of maintenance your plants will need. In general, though, here are a few pruning tips to help get you started.

• When pruning, be sure to keep your hedge shears  or pruning clippers as sharp as possible. A dull cutting edge results in frayed, ragged ends that can admit diseases and fungi more readily. Sterilize your clippers after each cut, especially if removing diseased wood, with alcohol or a bleach/water solution. A disinfectant aerosol also works and is easier to carry around than open liquid containers.
• When removing side branches, make the cut as close to the main stem as possible. Longer stums will die back, creating inviting entry points for insect and disease.
• When pruning a main stem, cut back to an outward facing side stem or leaf bud. This will promote new growth upward and outward, creating a more pleasantly shaped shrub.
• Know the blooming season of flowering shrubs before pruning. Some bloom on this season's wood (usually mid-late summer or fall bloomers) and can be pruned early in the season. Others that bloom on last years wood (usually spring bloomers) should not be pruned until after blooming.
• When pruning hedges such as boxwood or yews, allow the lower branches to grow slightly longer than higher ones. This will help the bottom half of the plant get the sunlight it needs for full, dense growth and thus prevent the thinning that often occurs at the bottom of hedges that have been cut too square.
• In cold-winter areas, avoid pruning 6-8 weeks before frost. Pruning at this time would stimulate new, tender growth which would be prone to cold damage and winter dieback.

Insect and Disease Control

It's nearly impossible to summarize in a general discussion the multiplicity of diseases and insects that affect shrubs. Some species are virtually disease free while others are magnets for any number of pests. Before planting some shrub you fell in love with on a national gardening show, ask a local nursery professional if it's a good choice for your area.

Many common fungus diseases, such as black spot, powdery mildew, rust and leaf spot can be prevented and controlled with a regular fungicide treatment program. These treatments should begin before disease conditions exist (heat and humidity, for example), and continue faithfully until those conditions no longer are present.

Insect pests common to a variety of shrubs include aphids, whiteflies, scale, mealybugs, leafminers, leaf hoppers, and slugs and snails. Insect pests can not only do damage directly, by feeding on leaves and sucking juices, but they can also be vectors (carriers) for plant diseases, or create injuries that allow diseases easier entry into plant tissue. After identifying the insect pests, control them with insecticidal soap, neem oil, pyrethrin or other insect spray.

Propagation

Most shrubs can be grown from from stem cuttings taken from the parent plant. The timing and type of cuttings varies widely, though. For best chances of success, consult a nursery professional for the right time and best method for taking cuttings of your favorite shrubs.

One of the easiest ways to grow a new plant from the parent shrub is to leave the stem attached to the plant.

• Simply choose a low-hanging stem, make a shallow wound on the stem 6-12" from the stem tip.
• Apply Schultz TakeRootâ rooting hormone to the wound, then pull the stem down so it is in contact with the soil.
• Mound a little soil over the wounded area and secure with a brick or wire hook so it remains in contact with the soil.  

Roots will grow from the wounded area in a few weeks to a few months, depending on the plant.  After they develop, simply cut the stem at a point between the new roots and the parent plant, and replant your new shrub.