Fertilizing and Watering Trees 19 



Watei that is ciK-niically or hygroscopitaliy bound is not 

 available to plants. Cira\ itational water rapidly seeks a lower 

 level in the soil or runs off on the surface and is of limited 

 importance. The amount of suspended capillary water in 

 soil depends on the texture and structure of the soil. The 

 maximum amount of capillary water a soil can hold, after 

 the gravitational water has percolated through, is called field 

 capacity. Water available to plants is at its maximum when 

 field capacity has been reached. 



How and when should you water trees? 



Plant roots require both moisture and air for normal 

 development, but trees can be overwatered. Adding large 

 quantities of water too frequently to heavy clay soils may 

 bring about a water-logged condition. With the exclusion 

 of air, roots decline and die, and trees and shrubs may be 

 killed. Such losses occur most frequently in disturbed soils 

 when plants are located in clay fill or in potholes in clay 

 subsoil following construction work. The soil around plants 

 in such sites should be tile drained. 



Recently planted trees 



Trees or shrubs that have been transplanted may need to 

 be watered for 2—3 years to provide an adequate water supply 

 while their root systems are becoming established. Some 

 trees are not fully established for 3-6 years. Trees and 

 shruf)s planted with bare roots normally require longer to 

 develop adequate root systems than do plants moved with 

 balls of soil. Older and larger plants require more time to 

 become established than do younger and smaller plants. 



A newly planted tree or shrub is most easily watered if a 

 circular mound of earth 3-4 inches high is prepared around 

 the plant at the edge of the planting hole (Figure 9). This 

 mound serves as the dike of a reservoir that should be filled 

 with water at 7- to 10-day intervals during the growing 

 season. The reservoir holds a supply of water adequate to 

 soak the soil of the backfill and the soil in the ball around 

 the plant roots. 



