LSU Agricultural Center….
Ornamental Horticulture E-mail News (June 2nd)

New Re-Scheduled Date for Landscape Horticulture Field Day at the Hammond Research Station

WEDNESDAY JUNE 11th – 4:30 pm

Landscaping with Pine Trees (from Allen Owings)

Louisiana has many great native trees. Pines, along with bald cypress, southern magnolias, and oaks are the native tree species in Louisiana that most of readily think of. We have loblolly pine (Pinus taeda), Virginia pine (Pinus virginiana), longleaf pine (Pinus palustris), shortleaf pine (Pinus echinata), spruce pine (Pinus glabra) and slash pine (Pinus elliottii), among others, to use in our landscape settings.

Hurricanes Katrina and Rita did major damage to pine trees in southeastern Louisiana and southwestern Louisiana in 2006. This is having a major long term negative economic impact on Louisiana’s forestry industry and also affected many of our residential and commercial landscapes. Unfortunately, many pines trees damaged homes and buildings as they fell. We can still, however, use pine trees successfully in our landscapes if the proper location and species is selected.

The best pine tree for landscape use in Louisiana is the spruce pine. It has a slow to moderate growth rate and matures at a size that works in medium to large size landscape settings. Spruce pines are much more adapted to adverse or varying soil moisture and pH conditions when compared to other pine species. Spruce pines can tolerate neutral to slightly alkaline soils and can also grow better in poorer drained soils that have some clay – although their growth certainly will be slower than if they were planted in more ideal silty, acid soil. Virginia pines are also slightly more tolerant of adverse growing conditions.

Pine trees vary greatly in size. Consideration needs to be given in this regard when planting in landscape settings. Shortleaf, Virginia and spruce pines are the smallest of the pines we have discussed in this article. They reach average heights of 25-50 feet with and average spread of 20-30 feet. The Virginia and spruce pines would be best suited to planting. Shortleaf pine would perform better in north Louisiana than in south Louisiana. Loblolly, slash and longleaf pines are more upright growing and get to be considerably larger than the other species. The longleaf pine stays in a “grass-like” growing stage for several years before upright growth commences.

Pines trees are limited in availability at garden centers but you can find the spruce and loblolly species. Seedlings are available every year (normally December – February) from the tree seedling sales office at the Louisiana Department of Agriculture and Forestry. Plant in the fall and winter months for best success.

Give some pine trees a chance in your landscape in room allows. They are great for perimeter landscaping efforts and the soil conditions required for most pines matches that of common ornamental shrubs such as gardenias, hydrangeas, camellias, sasanquas and azaleas.

Windmill Palms (from Allen Owings)

Palm use in home landscapes has gained considerable interest in the last few years. This resurgence can mainly be attributed to the lack of severely cold weather over the last 20 years. Most people remember the winters of the early 1980s and late 1980s that resulted in considerable damage to palms around the state.

One of the most reliable palms for Louisiana is the windmill palm (Trachycarpus fortunei). This species can be grown across the state and is one of the palms that can be planted in more northern locations. Windmill palms are cold hardy to 15-20 degrees and can tolerate lower temperatures for very short terms. 

These trees have average heights of 15 to 25 feet but can be as tall as 40 feet. Trunks are slender. Mats of dark brown, hair-like fibers coat the trunk on younger palms. Windmill palms like ample water but don’t do well in extremely moist soils or standing water situations. Low, poorly drained areas will significantly slow growth of windmill palms. Windmill palms are relatively slow growing so consider this fact when adding some to the landscape. High drought tolerance and moderate salt tolerance are characteristics of windmill palms. Place in a full sun location for best growth although plants will grow (at a slower rate) and adapt to partially sunny/shady situation.

While most of us now realize that fall and winter are the best times to plant the majority of ornamental plants in our landscapes, the best time to plant palms in Louisiana is May through September. The soil is warmest this time of year and warm soil is one of the most important criteria for palm root growth.

Rough handling of palm trees or severe vibrations during transport can break the tender bud, causing death many months down the road. It also is important to transplant the palm as soon as possible after digging. Never allow the roots to become dry. This would not be a problem when purchasing container-grown plants.

Maintenance is minimal on windmill palms once they are established in the landscape. Fertilization every couple years can aid in growth and foliage color. You can also consider removal of the oldest leaves but it is not a necessary practice.

Windmill palms are tough and durable. They can be used in narrow planting locations. Lawn grass will grow and ornamentals needing sunlight can be planted in beds underneath windmill palms because of their high foliage canopy. They make excellent focal trees and tropical accents.

Vitex (from Allen Owings)

One of the nicest small flowering trees for Louisiana landscapes is the chaste tree or vitex (Vitex agnus-castus). Mid spring through early summer is the main time for flowering on this increasingly popular plant.

Chaste trees are native to the Mediterranean region across to Central and Western Asia. We have begun to see more interest among home gardeners and commercial horticulturists in this plant over the past ten years. Plants reach heights of 15 feet in the landscape with a spread of 15-20 feet. Maintain as multiple trunk specimens (starting at a young age), similar to how you would maintain and shape crape myrtles. The plant form at maturity is a rounded vase shape. A grouping of three plants together makes a nice appearance or single specimen plants would work fine as a focal point in a private or public area of the landscape.

Flowers are lavender blue; very showy and fragrant. Most years, flowers appear in Louisiana the first or second week of May and last for about 6-8 weeks. Bees are attracted to the flowers. Black fruit is formed in the late summer and early fall. Mature fruit can result in seedling emergence in landscaped areas later on. There are only a minimum number of named cultivars on the market – Shoal Creek is probably the one most often available in the Gulf States area.

For a planting location, select a well drained, moist and fertile soil. Sandy or silty soil would be much better than clay soil. Establishment issues would be a problem in heavy clay soils. Soil pH is not critical – anywhere from slightly acid to slightly alkaline should suffice. A full to partial sun planting site is needed for best results.

Chaste trees have a fast growth rate, have high drought tolerance and can handle minor salinity issues in soil. Once in a while scale insects can be a problem and root rot does occur in a poorly drained soil.

You can get a second or extended bloom on these small trees by dead-heading the old flowers from the first bloom in late spring, early summer.