10 ORNAMENTAL CACTI. 



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 cylindrical 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 temperature. 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 of an 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 another set of feeding 

 roots can be produced, and it starves to death. For watering, a vessel 

 should be used that gives a fine, gentle spray, in order to avoid the 

 danger of washing the seeds from their position or of injuring the 

 delicate young seedlings. Watering should be done at least once a day. 

 The temperature of the propagating house or frame should be kept 

 as nearly uniform as possible and should not vary much from 70° F. 



The proper time for transplanting the seedlings differs for different 

 genera and species, but they should usually be left in the germination 

 pot until the plant shows at least three or four clusters of spines. By 

 that time the tissues will have become considerably hardened and a 

 very good root system will have been formed. The taller growing 

 species, such as Cereus, will be the first ones ready for transplanting. 

 Mamillaria and kindred genera and plants of similar growth will be 

 the last. The seedlings should be transplanted into a flat sufficiently 

 small for convenient handling, which should be provided with drain- 

 age openings in the bottom. It should be filled with the same kind 

 of material and soil as used in the germination pots, the surface to 

 be carefully leveled in the same way. The rows should be about an 

 inch apart, with the same interval between seedlings in the row. 

 After the flat has been filled with the seedlings a thin layer of clean 

 gravel should be placed all over the soil surface and close up around 

 the plants. The flats should then be placed in a perfectly level posi- 



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