24 SHADE TEEES. 



Gratings. In some cities the bases of trees are protected 

 and their roots given air, by means of iron gratings set in 

 openings in the pavement. Plate II. shows a number of these. 

 In exposed situations these gratings are valuable, but apart 

 from their considerable cost they must be raised frequently 

 and the space cleaned out. It is well to avoid their use as 

 far as possible. 



NOURISHMENT. 



More street trees suffer from starvation than from anything 

 else. In many places food, water and air are all denied ; and 

 the greater part of the harm is done by laying the pavement 

 close to the tree. Don't plant a street tree unless it can have 

 six square feet of open earth at its base. In Washington, 

 D. C., the regulation openings are 3 feet by 8 feet, or 24 

 square feet. (Plate IT.) A generous space of earth about 

 a tree is absolutely necessary for health. While a tree is 

 youn^ the soil in this opening should be stirred frequently 

 Tree roots to admit air and control evaporation ; after it 

 need air. becomes of good size grass may be allowed to 



cover the opening although constant cultivation will stimulate 

 growth. 



In summer if rain does not fall for several weeks the tree 

 should have water, for pavement, sidewalk and house fronts 

 become so heated that the evaporation from the leaves is 

 greatly increased. Unless the water thus drawn off is re- 

 placed the tree suffers. A thorough saturation of the soil 

 every week or ten days is better than more frequent sprink- 

 ling. A good plan is to build an earth dam about the tree, 

 three or four feet from its base, or as near that as the pave- 

 pienty of mcnt will permit, and fill the enclosed space 



water. with water, several times if necessary. When 



the water has all been absorbed, and the top soil is dry, break 

 down the dam and spread the pulverized earth over the wetted 

 area. That will retard evaporation. Be careful not to 

 water so frequently that the earth becomes soggy and sour. 



