'Groundwork' for March 24, 2013

Azaleas are Louisiana’s most popular shrub among home gardeners. Fall is the best time to plant azaleas, followed, in turn, by winter, spring and summer. The vast majority of azaleas are, however, planted in spring. This is, of course, when garden centers have the best selection and is the time of the year when gardeners see azaleas in bloom.

You can have long-term positive results with azaleas in your landscape by selecting the correct variety, planting properly and providing the most ideal growing conditions. With our mild winter this year, azaleas are blooming in landscapes ahead of schedule across Louisiana.

Before purchasing azaleas, make sure you find out the mature size of the plants you intend to buy. Depending on the variety, azaleas may mature at less than 2 feet up to 10 feet tall. Don’t purchase a type of azalea that will grow too large for the spot where it will be planted.

Spring-planted azaleas may take a little longer to become established than those planted in fall or winter. Flowering and shoot growth are going to occur at the time the azaleas are planted. This will slow down root growth and establishment.

Most gardeners really should avoid summer planting, although you can be successful planting at that time by providing extra care — primarily watering.

Many azalea varieties will tolerate full sun if given adequate moisture. Generally, however, azaleas grow best in a partial-sun to partial-shade environment. Four to six hours of morning sun provided by an eastern exposure is considered ideal.

Azaleas tend to have sparse foliage, look leggy and bloom poorly when planted in too much shade. If grown in too much sun, azaleas may wilt constantly during hot, dry weather and scorch on their leaf edges. Western sun exposure during summer and into early fall is hard on these plants.

Azaleas require good drainage but also need an even supply of moisture. They will not thrive in a location that is constantly wet or constantly dry. Uniformity in soil moisture is important for good growth and establishment in a landscape.

Consider texture and structure of your native soil. Amending this soil with pine bark or a similar organic material will likely be needed.

Many, many azalea varieties are recommended for Louisiana landscapes. Popular ones include the Southern Indica, Robin Hill, Satsuki and Encore groups. Azaleas need to be planted in the right place. In addition, proper cultural practices are very important to the long-term landscape enjoyment of Louisiana’s most popular flowering shrub.

Whether you have a young azalea planting or an older established planting, the correct cultural practices go a long way in maximizing landscape performance.

Practices to improve landscape performance of azaleas include:

Select a partial-sun to partial-shade planting location. This can be four to six hours of direct sun daily. Avoid late afternoon sun, especially in summer.

A southern and eastern exposure is preferred to a northern or western exposure.

A soil pH of 5.5 is recommended. Don’t guess on pH — soil test.

Plant so that the top of the root ball is level with or slightly higher than the soil of the bed. Prune the roots if necessary.

Proper spacing also is important because a crowded planting bed limits air circulation and can create conditions more favorable to disease development and azalea lace bug infestation.

Know how far the plant spreads for each variety you plant and space them accordingly.

Fertilize with a slow-release formulation in spring after blooming is completed.

Mulch with pine straw or similar material to a depth of 2 inches. Avoid placing mulch in piles around the lower stem of the plant.

Manage irrigation properly. Azaleas need uniformity in soil moisture — not too dry, not too wet. Avoid overhead irrigation when practical.

Prune lightly after spring bloom. Complete pruning for spring-flowering azaleas by July 4. Complete pruning for multi-seasonal flowering azaleas within two to three weeks after any bloom cycle is completed.

Plant sale

Save the date. The Master Gardener plant sale is April 13-14 at the LSU AgCenter Botanic Gardens, 4560 Essen Lane. Check out the plants for sale at http://www.mgplantsale.com.

Garden tours

The LSU Hilltop Arboretum 2013 Spring Garden Tours include an eclectic collection of Baton Rouge’s intimate spaces and grand gardens culminating with an unforgettable bonus tour in beautiful St. Francisville.

Three Sunday afternoon tours from 1 p.m. to 5 p.m. kick-off on April 7 with “A Walk in Walden.”

The tour features seven gardens set against a backdrop of magnificent lakes and wildlife in Walden Subdivision.

“A Pastiche of Garden Styles” on May 5 offers five gardens that embody our Southern garden traditions from formal to natural forms and eclectic plant collections.

On May 19, the season culminates with “An Afternoon in St. Francisville.”

There will be period gardens at Sunnyside Plantation, a picnic under the trees at St. Mary’s Episcopal Church, and a walk in a mature beech-magnolia woodland setting at the Mary Ann Brown Preserve.

Hilltop Spring Garden Tours ticket prices are two-tour and bonus series packet, $35 (with tickets available at each garden the day of the tour), and single tour tickets, $20.

Ticket and tour information are available online at http://www.lsu.edu/ hilltop or call (225) 767-6916.

Got a gardening question? Write to Bob Souvestre, horticulturist with the LSU AgCenter, at Burden Center, 4560 Essen Lane, Baton Rouge, LA 70809, or email to bsouvestre@agcenter.lsu.edu, or call Master Gardeners at (225) 763-3990.