For years, horticulturists have recommended the incorporation of organic matter into the backfill soil when planting individual trees and shrubs. This recommendation, because of university research results, has been slightly changed. Several factors will determine whether or not to add organic matter. Much information is available now on water movement in various soil structures and water relationships in soil and backfill medias. Everyone is aware of problems caused by too little or too much water and that either condition can cause plant stress and decline. The key to whether or not to amend soils with organic matter is generally determined on how the plant was grown and what type of soil is at the planting site.

Most field grown trees are dug, sold, and planted as B & B (balled and burlapped). The old recommendation of digging a large hole and adding organic matter provided good results because of the large planting pit size and not the addition of organic matter. By disturbing and improving the soil structure in compacted soils, the roots are able to establish quicker. Additions of fertilizers low in nitrogen and high in phosphorus and potash to the backfill will also aid root growth. Both materials are not easily leached to the roots when applied to the soil surface while nitrogen is. By slightly raising the planting height, drainage is also improved. Moisture relationships are very important in the first growing season of a newly planted tree or shrub. Most container grown ornamentals are produced in a loose, porous, soil-less media. These mixtures, where 100% of the roots are located, dry out very quickly. (Nurserymen find it necessary to water on a daily basis). After being planted in the landscape, it is necessary to keep the roots from becoming too dry during the long, hot summer days. The surrounding soil in a bed could become completely saturated following irrigation and could remain wet for several days. Meanwhile, the media - as it loses moisture faster than soil - could dry out. Research indicated the lack of water movement from one bulk density (soil) to another bulk density (media).

That's why it is necessary to get the roots in contact with soil when planting -- i.e., be sure to disturb the root system when locating the plant in the hole. Don't be misled to water only when the soil dries out - the media probably was dry long before!

Mounding a ring around the stem and root system is a good practice which will allow water to move downward to the roots and not become runoff. Azaleas are extremely sensitive to this problem of drying out during the establishment period. An appropriate watering schedule would be one which provides water often during the early establishment and growing period, thus directing the roots out into the surrounding backfill and soil. This schedule should change to allow less frequent applications as the plant becomes established.

In summary:

1. Good drainage is essential for plant growth and development; therefore, always provide adequate drainage.
   
2. When planting B & B material where soil is in the root ball, dig a large hole, backfill with native soil and mulch well. (In gray or white "plastic type" soils, organic matter has proven to aid in aeration; and in sandy soils, organic matter helps hold moisture.)
   
3. When planting container-grown plants, disturb the root system, add organic matter in the backfill, thus creating a homogeneous mix between roots and surrounding area.
   
4. A three or four inch layer of organic mulch can be applied to any newly planted tree or shrub bed area.

Revised 2/16/2006.