Sustainable Landscape News Distributed 12/18/09

Many landscape trees are planted from fall through the winter in Louisiana. Homeowners need to be aware of some of the common mistakes made in planting, establishment and follow-up care of trees.

Many times, poor tree performance in residential landscapes, commercial landscapes and municipality plantings can be traced to improper planting techniques. Here are some examples of a few common mistakes to avoid when adding new trees to your landscape.

– Planting root balls too deeply. The best management practice is to have the top of the root ball be at the same level or slightly higher than the soil grade. Do not cover the lower trunk with soil.

– Improper planting hole diameter. Ideally, the diameter of the planting hole should be two to three times larger than the tree’s root ball. The poorer the condition of the soil in terms of drainage and aeration, the wider the planting hole should be dug. This allows for lateral root development and expansion. Remember that tree roots grow out from the planting hole into the surrounding soil.

– Planting root-bound plants. It is consider a best management practice, especially in container-grown trees, to cut the encircling roots enough to encourage outward root growth and prevent future circling.

– Excessive mulch or no mulch. Too much mulch or not enough mulch is common. Do not pile mulch around the base of trees. The recommended mulching depth for newly planted trees is 3 inches to 4 inches. Pine straw, pine bark and hardwood bark are good mulch materials.

– Excessive amendments to backfill soil. Backfill soil is the soil removed from the planting hole. The current recommendation from the LSU AgCenter is to return to the planting hole the soil that came from it. Do not amend backfill soil with pine bark, compost or similar materials. This will create a change in the soil texture from the planting hole to the surrounding soil, and water will migrate from the surrounding soil into the planting hole and saturate the root system – the “soup bowl” effect.

– Improper watering. Newly planted trees need to be sufficiently watered-in. This watering eliminates air pockets in the soil that dry out the root system. Apply water at the edge of the original root ball and outward. Do not apply water next to the main stems.

– Pruning at planting. Pruning guidelines suggest that the only pruning of shoot growth that should be done at planting is to remove any dead, broken branches, suckers or similar sprouts. Leave branches on the lower part of the trunk for a year or so to encourage trunk development. Excessive pruning of shoots at planting also can promote additional shoot growth at a time when root growth is desired.

– Soil pH and nutrient content. How many of us actually have a soil analysis done prior to planting? Knowing your soil pH is important. You may have heard the term “don’t guess, soil test.” A soil test indicates the status of soil nutrients. If potassium and phosphorus readings are high on a soil test, fertilizing with 8-24-24 or a similar material probably is not needed. But if these values are low, fertilization would likely be of value.

These are just a few items to keep in mind to be more successful with tree planting.

Visit LaHouse in Baton Rouge to see sustainable landscape practices in action. The home and landscape resource center is located near the intersection of Burbank Drive and Nicholson Drive (Louisiana Highway 30) in Baton Rouge across the street from the LSU baseball stadium. For more information, go to www.louisianahouse.org and www.lsuagcenter.com/lyn.

Rick Bogren