Azaleas

20 April 2005

Virginia Cooperative Extension, Charlottesville/Albemarle County Office
460 Stagecoach Road, Charlottesville, Virginia 22902
phone: 434.872.4580   fax: 434.872.4578

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If you are like most folks you probably have an azalea or two in your landscape. If you are looking forward to your azalea spring bloom and find they do not do so good you might want to rethink how you are caring for these plants. Even if your azaleas are doing fine there are some things you can do to keep them healthy.

Azaleas are of the Heath or Ericaceae Family of plants and prefer a cool, partially shaded site. Some varieties can tolerate full sun but most prefer an area that is not exposed to long periods of sun and drying winds.

Azaleas grow best when planted in acid, well-drained soils with a pH not much higher than 5.5. A soil rich in organic matter is ideal for azaleas. If your soil does not drain well digging a planting hole 3 or 4 times larger than is needed, adding crushed rock to the bottom and rich topsoil as a backfill will not solve all drainage problems. Holes dug in poorly drained soil will only fill with water and continue to hold this excess over a long period of time no matter the size of the hole. When soils are saturated, the amount of oxygen available to roots becomes very limited and roots become susceptible to rots.

To solve this problem it is generally recommended to plant them in a raised bed. By elevating the planting area one can insure good surface and internal drainage. Another option is to skip the hole and plant at grade level. Building up around the rootball with topsoil and plenty of organic matter, such as mulch or compost, can provide the protection from the elements the plant needs. Do not add fertilizer to the backfill at time of planting.

When planting balled and burlapped plants be sure to remove any nylon strings or wire from the rootball. The burlap can remain around the rootball but be certain there is not a plastic liner inside the burlap. Many containerized plants will become pot-bound and will require special attention before planting. The layer of matted roots around the outside surface should be cut, loosened, or frayed out before planting. If not, the roots will fail to grow out into the surrounding soil and plants will be more susceptible to drought.

Watering newly planted azaleas is essential. If planted in a well-drained soil rich in organic matter, frequent watering will be required. The backfill in the planting hole will dry out much faster than the original soil around the plant. Be sure not to apply quantities of water that will waterlog the media.

A 3-4 inch layer of organic mulch around azaleas is recommended. This will help to discourage weeds, prevent soil crusting, hold moisture during dry periods, and maintain a more uniform soil temperature. It is important to keep the mulch from touching the plant. Mulch piled onto the woody part of any tree or shrub is an invitation for disease and insect trouble.

Azaleas grow best with a moderate and even level of fertility. There are several special azalea fertilizers available which are excellent when used at recommended rates because of their slow release ability. Most homeowners will get satisfactory results from an 8-8-8 or 10-10-10 analysis. Over fertilization can cause severe damage. Therefore, if you are not using slow release fertilizer, split applications can be made in March, May, and July. Follow the directions on the label. In general, small plants, less than 12 inches in height, will need 1 teaspoonful per application. For larger plants, a level tablespoon per foot in height will be sufficient. For large bed areas, 2-3 pints per 100 square feet can be broadcast. Maintaining the correct pH (somewhere between 5-5.5) and fertilizer requirement can only be determined by soil testing.

Contrary to popular opinion, many azaleas do need pruning. Pruning is especially desirable to produce more uniform and compact growth for tall-growing cultivars. Any heavy pruning should be done immediately after the flowering period. Around here the best time to prune is May, June, and July. Tall, rangy limbs that appear in the top of the plant should be removed down inside the body of the plant. To induce branching, pinch out tips of new growth between flowering and the first of July. Later pinching will reduce flower production for next year. Always remove any dead or injured branches when shaping or heading-back azaleas. Dwarf azaleas also benefit from pruning. This gives better shape and improves flower clusters on established plants.

Some common problems associated with azaleas include the following. Iron chlorosis (leaves turn yellow between veins, but veins remain green) is a problem in high pH soils. Insect problems are the azalea lacebug, aphids, leaf miners, scale insects, and whitefly. Diseases are Phytophthora root and crown rot, Ovulinia petal blight, and powdery mildew.

If you are looking to purchase plants, consider your local garden centers, nurseries, farmers markets, and plant sales. This area has a good variety of garden centers and nurseries. The garden centers and nurseries you can find in the phone book. Here are a couple markets to try:

• Nelson County Farmers Market, Saturday mornings 8 am to 12 noon from May through October, Route 151, Nellysford
• Charlottesville City Market, Water & First Streets - 7am-12noon, Saturdays, mid-April to end of October

Some local plant sales in the next few weeks are as follows:

The Fluvanna Master Gardeners Third Annual Seminar and Plant Sale will be held on April 30 from 8:30 to 3:30 at the Beaver Dam Baptist Church on Rt. 250. Seminar topics include heirloom apples and vegetables and native plants. Seating is limited. Call 591-1950 for details.

The Nelson County Master Gardeners along with the Rockfish Valley Community Center and the Rockfish Valley Ruritans will sponsor their Fifth Annual Pre-Mother's Day Plant Sale on Sunday, May 1, 2005, from 10am -4pm at the Ruritan Park off Rt. 151. There will be plant and garden craft vendors. The Master Gardeners will sell plants and answer gardening questions. Call 361-9147 or 361-1309 for details.

On Saturday, May 7, from 9am to 12pm, the Piedmont Master Gardeners of Charlottesville & Albemarle County will have their plant sale at the Meadowbrook Shopping Center. The Master Gardeners will sell plants and answer gardening questions. Call 872-4580 for details.

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For more information about this and other landscape topics contact your local Virginia Cooperative Extension office. The local Virginia Cooperative Extension office numbers are Albemarle 872-4580, Fluvanna 591-1950, Greene 985-5236, Louisa 540-967-3422, and Nelson 263-4035.