Rhododendrons are ready

Some new, heat-tolerant rhododendron cultivars are coming from the Southern Living Plant Collection. These were developed to thrive in the Deep South while performing equally well in traditional rhododendron areas.

The Southgate hybrids bloom in early April in south Louisiana and were developed by John Thornton, of Franklinton.

These plants have been trialed in the New Orleans area and in their City Park Botanical Gardens for several years. And now wholesale production and commercial branding are making them available to gardeners throughout the South. Five varieties are available.

Southgate Brandi features deep pink buds that open to pink, ruffled blooms with a dense habit and dark green, recurved, glossy leaves.

Southgate Breezy sports medium-pink buds that open to white with a prominent maroon blotch and a medium-dense habit with medium-green leaves.

Southgate Radiance showcases deep lavender buds that open to light purple and has a medium-dense habit.

Southgate Divine has light-pink buds opening to white with purple specks and has a medium-dense habit with medium-green leaves.

Southgate Grace has deep pink buds that open white, a dense habit and recurved leaves.

Southgate Breezy, Radiance and Divine all grow to 4 feet tall by 5 feet wide in 10 years while Brandi grows to 3 feet tall by 4 feet wide. Grace reaches 4 feet tall by 6 feet wide in a decade.

Rhododendrons require cultural conditions similar to azaleas. Shade during portions of the day, especially early to late afternoons, is needed. The soil pH required for optimum growth is 5.5.

Soils need to be enriched with organic matter and it is important to plant in raised beds 8 to 12 inches high. Mulch with pine straw.

Maintain uniformity in soil moisture for best success. Do not plant deeper than what plants were growing in the containers.

Use caution

With all the activity of spring planting and adding trees, shrubs, ground covers, perennials and bedding plants to the landscape, this is also a time to be cautious about creating problems that could bring termites into your home.

LSU AgCenter experts offer these suggestions to reduce the possibility of termite problems:

Place gutters and slope your landscape beds so water drains away from your house.

Keep mulch in beds adjacent to the house pulled back about 12 inches from the foundation.

Do not add fill dirt around the foundation or under porches or steps without contacting your termite company for retreatment.

Do not disturb the chemical barrier at the base of the slab or around pilings by digging into it during bed preparation.

Promptly remove all scrap wood and wooden debris from the landscape.

Pine straw appears to be the mulch that is least attractive to termites. Avoid using wood chips to mulch beds adjacent to the house or other structures.

Use metal edging, decorative bricks or border plants to edge your beds.

Avoid landscape timbers, railroad ties or other wooden materials that may serve as food for termites.

When watering, avoid spraying water against the foundation of your house.

Leave at least 2 inches of space between your house and a deck or other wooden structure outside. Build decks and other structures on concrete pads and treat around the pads and posts.

Do not allow clinging vines, such as English ivy or creeping fig, to grow on the wall of your house.

Garden chores

Some garden chores to consider during April include the following:

Even after spring bulbs that will reliably return each year have finished flowering, wait until the foliage turns mostly yellow before cutting it off. Food is being manufactured and stored for next year’s blooms.

Mulch plants to reduce watering requirements, suppress weed growth and minimize soil temperature changes. Excellent mulches are pine straw, chopped leaves and pine bark. Mulch should be applied 2 inches thick for effective weed suppression.

Coleus are great annual bedding plants for Louisiana’s landscapes. Try some of the newer sun-loving varieties.

Fertilize shrubs during the spring using a general purpose fertilizer. Carefully follow the label directions.

Watch for insect problems this spring. Lace bugs on azaleas and aphids or whiteflies on gardenias are common. Also, examine camellias, sasanquas and hollies for scale insects on the lower foliage. Control with acephate, imidacloprid or horticultural oil sprays.

To encourage more rapid re-blooming, pinch off old flowers on bedding plants after their first flower cycle is completed this spring.

If your crape myrtles have had problems with crape myrtle aphids and the unattractive, black sooty mold they cause, treat your trees now to prevent problems this summer.

Apply a drench of imidacloprid insecticide to the base of the tree and the tree will be protected from aphids all summer.

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.

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.