4 CIRCULAR 66, IT. S. DEPARTMENT OF AGRICULTURE 



drainage of superfluous water. These algae will in time grow over 

 the little seedlings that have survived other adverse conditions and 

 will smother them. To combat the algae the pots should be thor- 

 oughly sterilized just previous to being used, and to accomplish this 

 object two efficient methods have been employed. One method is 

 to bake or burn the pot$ so that all life on them or in their pores 

 may be destroyed. The other method is to soak the pots for a time 

 in a weak solution of copper sulphate and then thoroughly wash 

 them. If a very strong solution of the copper sulphate is used, 

 some of it will be left in the pores of the clay, and later when the 

 seedlings are being watered enough may pass through the soil to 

 injure the tender young plants. 



Reasonable care should be exercised in preparing the pot for plant- 

 ing. As a rule, the drain hole in the bottom of the pot is too small 

 and is easily clogged. This hole should be enlarged, as thorough 

 drainage must be maintained in growing cacti. The pot should be 

 filled to one-fourth its depth with small bits of broken pots, and on 

 these the prepared soil $hould be placed and pressed or shaken 

 together firmly but not packed hard. The soil surface is then leveled 

 by the use of a round, flat-faced tamper of a diameter to just fill 

 the pot. The soil should not be packed but should be lightly tamped, 

 with only sufficient effort to produce a smooth, level surface. This 

 surface should be about half an inch from the top of the pot. Over 

 it the seeds are evenly distributed and then covered with a very thin 

 layer of $oil, upon which is spread a layer of fine gravel to a depth of 

 about one-fourth inch. This layer of gravel is important in many 

 ways. As the pots are later watered with a fine spray, it prevents 

 the surface of the soil from washing and consequently keeps the 

 seeds from being disarranged. It also promotes the free passage 

 of moist air through the spaces between the bits of gravel, which, 

 together with the shading by the gravel, prevents the surface of the 

 soil from becoming dry and baked. It also checks the growth of 

 algae over the soil surface. 



As the seedlings grow they easily force their way through the 

 gravel to the sunlight. For the first few months of their existence, 

 cactus seedlings are but small, globular, balloon-shaped or cylindri- 

 cal bodies, composed of very thin-walled cells filled to turgidity with 

 water. They are so tender and delicate that they readily "damp 

 off" if subjected to a sudden change from a high to a low tempera- 

 ture. The death rate of seedlings from this cause has been greatly 

 minimized or almost wholly checked by the use of the gravel over 

 the surface of the soil. This layer, with its intervening spaces, acts 

 as a protection from sudden changes in temperature during that 

 period of their growth when the seedlings are most susceptible to 

 injury. By the time they have grown sufficiently large to project 

 beyond the gravel they have become hardier and more robust in 

 structure. Again, the gravel layer is of great value in that it keeps 

 the surface of the soil moist. The little seedlings have exceedingly 

 fine and delicate roots which spread out near the surface of the soil. 

 If this surface is allowed to dry out to the depth of one-eighth inch 

 or more, these delicate rootlets will be destroyed and the seedlings 

 will be damaged or killed. In most instances the diminutive plant 

 has not enough food stored up in its body to keep it alive until 



