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WORTH REPEATING 



Reducing Losses of Container Grown Plants 

 in Landscape Plantings 



Gerald Smith, Henry Clay, and ]ohn Gibson 

 Extension Horticulluralists, The University of Georgia 



HEALTHY CONTAINER-GROWN 

 shrubs with active roots can be 

 planted in commercial landscape 

 plantings and die within a short 

 time. Here are some problem areas 

 that often affect the survival of re- 

 cently planted container-grown 

 shrubs in Georgia: 



Problem #1. 



Rapid soil moisture consumption 



from container-grown plants. 



Research from the University of 

 California indicates that the soil of 

 container-grown plants can lose 

 moisture faster when planted in 

 some backfill soils than when the 

 same plant was growing in the con- 

 tainer. If the plant is not checked 

 frequently, it can die within a few 

 days if conditions are favorable for 

 rapid loss of moisture by transpira- 

 tion through the leaves. 



Problem #2. 



Imbalance of top to roots. 



Imbalance between root water 

 absorption ability to leaf water loss 

 is a major cause of death in re- 

 cently transplanted container-grown 

 shrubs. These plants transpire wa- 

 ter through the leaves at a normal 

 rate; however, their water absorp- 

 tion ability is greatly restricted due 

 to the small area of soil that they 

 occupy and thus are able to re- 

 move water from. Plants with heavy 

 tops are especially susceptible to 

 drought stress. Well grown con- 

 tainer Japanese hollies such as 

 'Hetzi' and 'Compacta' are ex- 

 amples of shrubs that will die sud- 

 denly due to this problem. As 

 plants expand the roots out into 

 the backfill soil within two to three 

 months, the problem becomes less 

 critical. 



Solution. Careful attention to re- 

 cently transplanted shrubs during 

 periods of high leaf transpiration 

 (high temperature, high light and 



rapid air movement, and low hu- 

 midity) is important. 



Problem #3. 



yfJater holding capacity of container 



mtKes. 



Container mixes are ideal for pro- 

 ducing high-quality shrubs in con- 

 tainers. These mixes, however, usu- 

 ally do not have ideal water hold- 

 ing capacity once the shrub is 

 planted in the ground. Until the 

 roots move into the surrounding 

 soil, the shrub is very susceptible 

 to drought stress 



Solution. Fortunately, the solution is 

 simple, yet effective. Knocking the 

 soil ball of the container-grown 

 plant several times against a hard 

 object will easily expose the surface 

 root mass. When planted, these 

 roots are immediately in contact 

 with the surrounding soil which has 

 a far greater water reserve than 

 does the soil of the container mix. 

 The removal of the surface soil is 

 preferred to the older recom- 

 mended practice of cutting the sur- 

 face roots. If practical, the roots 

 should also be spread out. The 

 possible solution of growing the 

 shrubs in a heavier mix is not prac- 

 tical for the grower since this would 

 greatly increase root rot problems 



Problem #4. 



Planting with the container soil dry. 



Occasionally, container-grown 



shrubs are planted when the undis- 

 turbed container soil is dry with the 

 assumption that the shrub can be 

 watered later after it is planted. It 

 can be extremely difficult to wet a 

 dry container after it gets into the 

 ground The results are a plant in 

 wet backfill soil, but with most of 

 the roots located in an environment 

 that is completely dry. Death or se- 

 vere drought stress can result in a 

 few days during hot weather. 



Solution. Disturbing the soil ball 



and thoroughly wetting the soil ball 

 before planting will eliminate this 

 potentially serious problem. 



Problem #5. 



Failure to direct water where needed. 



Repeated problems have been en- 

 countered when overhead sprinklers 

 were used to provide water for re- 

 cently planted shrubs. Sprinklers 

 tendency to wet a large area, but 

 only to a depth of two to three 

 inches. This provides very little 

 useful water to the container grown 

 plants. 



Solution. Erecting a ring of soil 

 around the plants and hand water- 

 ing with a hose is the best ap- 

 proach during the initial period af- 

 ter planting. If a sprinkler system is 

 used, the nurseryman should obtain 

 a soil probe to determine how 

 deeply the water has penetrated. 



Problem #6. 



Failure of roots to become established 



in the surrounding soil. 



It is quite possible for the roots of 

 a container shrub to make almost 

 no development into the backfill 

 soil if the backfill soil holds exces- 

 sive water during wet periods and 

 is thus poorly aerated. A combina- 

 tion of a heavy clay soil plus a 

 planting site where water accumu- 

 lates usually results in the most se- 

 vere problem. 



available in this situation. Probably 

 the most practical one is to replant 

 with shrubs that have greater toler- 

 ance to poor soil aeration. 



Ornamentals which have average 

 or above-average tolerance to moist 

 soil conditions include: bald cy- 

 press, 'Bradford' pear, dwarf Chi- 

 nese holly (Cornuta rotunda), red 

 maple, sweetbay magnolia [Magnolia 

 virginiana], wax leaf ligustrum, and 

 weeping willow. (This article was 

 written with southern plant varieties 

 continued on page 26 



Ihe Plantsman 

 28 



