Allen D. Owings, Young, John, Gill, Daniel J. | 10/10/2008 12:17:28 AM
By LSU AgCenter Horticulturists
A survey of LSU AgCenter county agents reveals five major landscape problems in Louisiana yards and gardens. These problems are improper or inadequate landscape bed preparation, not knowing soil fertility and pH, improper ornamental plant selection, winter damage to plants and shade tree care.
Many of the problems associated with our turf, gardens and ornamentals can be prevented or overcome if proper cultural practices are maintained. These cultural practices are referred to as best management practices or BMPs.
Improper bed preparation tops the list of problems. With our high amounts of annual rainfall and poorly drained native soils around much of the state, bed building is critical. Adequate bed preparation before planting helps avoid later problems.
To prepare a bed properly, first remove weeds and any other unwanted materials. Next, till the soil to a depth of about 8 inches and incorporate 2 to 4 inches of composted organic matter, such as composted bark, aged manure or compost. This treatment will improve internal drainage of the soil and help with aeration and oxygen exchange in the root zone. Raising the bed to 6 to 8 inches also will improve drainage.
Soil fertility and pH affect how well ornamentals will do. Most of the ornamentals grown in Louisiana prefer a soil pH of 5.5 to 6.5. Some of our common landscape plants actually prefer a soil pH in the lower end of this range. Examples include azaleas, gardenias, petunias, blueberries and vinca (periwinkle).
A soil test will reveal your soil’s pH level. Fall is a great time to take a soil sample and send it for analysis to the LSU AgCenter soil testing lab. The base price is $7 per sample. Check with the county agent in your parish for details.
All growing plants need an adequate supply of nutrients for optimal growth and development. Proper fertilization is necessary. Incorporate nutrients into the soil at time of planting. A good, slow-release fertilizer works best. It is helpful to know if your current native soil has low, medium or high levels of fertility (determined by a soil test).
What are the fertility requirements for the ornamentals you plan to grow? You need to answer this question to apply best management and sustainable practices. Remember, over-fertilizing is generally worse than under-fertilizing or not fertilizing at all. Over-fertilization leads to excessive plant growth, weaker growth, fewer flowers, leaching and runoff (which then become pollution) and can actually damage plants.
Many home landscapes have examples where the wrong plant is in a particular spot. One example is a sago palm placed next to a sidewalk, in a small space or too close to the house. The plant grows too large for the area. Selecting the correct plant for the location is critical. Consider maintenance requirements, sunlight exposure and traffic patterns. Think about the plant spread (width) as well as its height at maturity.
Winter damage primarily occurs with tropical plants, which cannot tolerate cold weather. Unusually severe cold can sometimes damage plants that are normally hardy, such as azaleas. Mulching with leaves, pine straw or similar materials is a great way to reduce freeze damage to roots and lower stems. Covering tender plants with fabric or plastic sheets is also a common preventive measure.
To minimize work needed to protect tender plants over the winter, plant tropicals sparingly and focus primarily on plants that are reliably winter-hardy. Proper pruning, fertilization and irrigation are also important in reducing cold damage. Make sure plants susceptible to cold damage are not drought-stressed during the fall months.
The problems with shade trees all across Louisiana are considerable, particularly in our expanding residential areas. Construction takes a serious toll on the root system of trees. To avoid such damage, protect trees during construction, and do not trench, excavate, change soil grades or modify drainage patterns around trees.
The grade around trees should not be changed more than 1 inch per year. Proper tree selection and proper pruning and care when trees are young will improve long-term performance of shade trees in your landscape.
Follow these best management practices to avoid the five major problems in Louisiana landscapes. More information on sustainable home landscaping and details on horticultural work at LaHouse can be found at www.lsuagcenter.com and www.louisianahouse.org.
LaHouse is located near the intersection of Burbank Drive and Nicholson Drive (La. Highway 30) in Baton Rouge across the street from the new LSU baseball stadium.
Contacts: Dan Gill at (225) 578-2222 or firstname.lastname@example.org
Allen D. Owings at (985) 543-4125 or email@example.com
John Young at (225) 578-2415 or 578-2222 or JoYoung@agcenter.lsu.edu
Editor: Mark Claesgens at (225) 578-2939 or firstname.lastname@example.org