PROPAGATION. 105 



The amount of growth made by cuttings varies much, 

 according to the kind of plant, size of cuttings, soil, etc. 

 The most of our Willows will make a growth of three or 

 four feet on good soil in one season from ordinary cut- 

 tings. 



The Solar Pit. There are many trees that will not 

 grow from cuttings unless they have their roots started 

 a little before planting. This is most easily accom- 

 plished by means of what is called the "solar pit," which 

 owes its success to the fact that cuttings root first at the 

 warmer end. It is made and used as follows: The bun- 

 dles of cuttings are heeled-in as recommended. In the 

 spring they are taken out and buried close together, with 

 the butt ends uppermost, in a warm, sunny spot and 

 covered with about six inches of soil. A hotbed frame 

 with sash is then put over the spot to warm the soil. 

 Sometimes, instead of using sash, the soil over the cut- 

 tings is covered with a foot 

 or more of fermenting manure. 

 In either case the soil is 

 warmed and the formation ..,..,^,,_ ^, -,.^. 



of roots encouraged. In using _^ "^''"^ , .^ , 

 - , . ^ , , Fig. 26.— The solar pit, show- 



the solar pit, the rootmg ing bundles of cuttings in 

 process should not be carried P^ace under glass. 

 so far as to permit roots to show plainly, as they arc 

 liable to be broken off in planting out; but the cuttings 

 should be planted out as soon as they show signs of 

 heeling over on the butt end. This heeling-over process 

 is called callousing, and in many plants necessarily 

 precedes the formation of roots. 



LAYERS. 



Layers are portions of the branches of trees, shrubs, 

 or vines which are covered' with earth without being 



