PROPAGATION BY CUTTINGS. 



349 



so as to raise the bottom of a small 60-sized 

 pot placed within the other, so that the tops 



of both should 

 Fig. 123. be level. The 



^^^^^^^^^^^^^^^^ with ' water,'" <^ 

 striking cuttings. which, passing 



through the 



sides of the pot, reaches the cuttings. Others 

 have, to effect the same end, placed a flat piece 

 of crock under the base of each cutting, at such 

 a depth in the soil that the cutting shall rest 

 upon it ; and others insert a smaller pot, turned 

 bottom upwards, within a larger one, and insert 

 the cuttings round the sides of the inverted 

 pot. This is a good plan where bottom heat is 

 applied, as it ascends within the inverted pot, 

 and reaches the roots better than if it had to 

 ascend through the soil. 



Cuttings of plants that are slow in forming 

 a callus are sometimes half severed from the 

 parent plant, and allowed to remain so until the 

 wound be healed and the callosity begin to form, 

 a circumstance which leads to the belief that air 

 is a necessary agent in its formation. Plants 

 containing a large pith are often difficult to 

 strike, and those with hollow stems are equally 

 so : in such cases the joint or node should inva- 

 riably be cut through ; and in this, as in all other 

 cases, the cut should be made with a clean 

 sharp knife. Kegarding the choice of cuttings, 

 where strong and upright plants are required, 

 the tops of the leading shoots, or the strongest 

 of the side ones nearest to them, should be 

 chosen ; and where less robust and bushy plants 

 are aimed at, then the more slender side-shoots, 

 and those nearest the bottom of the plant, should 

 be taken. These latter shoots, if taken off with 

 what is technically called a heel — that is, a small 

 portion of the older branch at the junction be- 

 tween the two — will strike more readily, as the 

 portion of heel removed is in general well sup- 

 plied with very minute incipient buds. 



The best time for taking off cuttings of green- 

 house and stove plants is in spring, or early in 

 summer, that the young plants may be estab- 

 lished before next winter. There are, however, 

 circumstances which set this rule aside, and in 

 such cases the process must be carried on at 

 other seasons. Many hard-wooded plants re- 

 quire to be slightly excited into growth early in 

 spring, to cause them to push out shoots fit for 

 the purpose; by this means many heaths and 

 VOL. IX. 



other plants which do not strike readily, or take 

 a long time to root, are pushed on, so as to be 

 established before the close of the growing 

 season. 



Bottom heat— The importance of bottom heat, 

 accompanied with sufficient light and moisture, 

 is thus spoken of by Professor Balfour, in " Class 

 Book of Botany," p. 658 : " In causing cuttings 

 to strike, we require a somewhat higher temper- 

 ature than that of the climate in which they 

 naturally grow. A willow-cutting stuck in the 

 open ground will strike root; but it does so 

 much faster, and more vigorously, when placed 

 in a hot-bed. A white-thorn cutting in the open 

 ground will not root at all ; in a warm propa- 

 gating-house it will do so readily. It is not the 

 temperature of the atmosphere, but the tem- 

 perature of the soil that requires to be raised. 

 We must first obtain roots, and then leaves will 

 follow. The cellular tissue of roots is first pro- 

 duced by a local process, and the production of 

 this tissue is kept up by the heat of the soil : 

 hence the necessity for bottom heat, in order 

 to secure good roots in the first instance ; and 

 without them there will be no vigorous leaf- 

 buds." This has reference more directly to cut- 

 tings of soft- wooded plants, which, immediately 

 after being inserted in the soil or sand, begin to 

 form roots, often in the course of a few days. 

 Others require longer time ; and some require 

 months, before the stimulating effects of heat 

 should be applied. On the advantage of bottom 

 heat applied at the proper time, Dr Lindley re- 

 marks, in "Theory of Horticulture," p. 213: 

 " This is for the purpose of giving them a sti- 

 mulus at exactly that time when they are most 

 ready to receive it. Had they been forced at 

 first in bottom heat, the stimulus would have 

 been applied to cuttings whose excitability had 

 not been renovated, and the consequence would 

 have been a development of the powers of 

 growth so languid that they probably would not 

 have survived the coming winter ; but the sti- 

 mulus being withheld till the cuttings are 

 quite ready for growth, it tells with the utmost 

 possible effect." 



Many plants, like the oleander, will strike 

 roots if their ends be placed in water, and, when 

 sufficiently rooted, may be planted in ordinary 

 soil. Others, such as pelargoniums and verbenas, 

 will root readily if planted in damp sphagnum ; 

 and many shrubs, such as the rose, will root 

 readily in half-decayed flax-dressers' refuse. 

 Most plants will root, if set in the soil natural 

 to them ; but the universal medium in which 

 all valuable plants, and such also as are difficult 

 to root, succeed best in, is clean silver sand laid 

 over the soil in which the plant delights, so that 

 when the roots pass through the sand they find 

 their natural supply of food awaiting them. 

 Many plants, although they will root freely in 

 sand, refuse to grow in it, and in such cases the 

 cuttings should be removed from it as soon as 

 their roots are formed, and potted in soil con- 

 genial to them. 



Cuttings of heaths, and similar hard-wooded 

 plants, may be safely sent to a great distance, if 

 placed loosely in a tin case, with from a tea- 

 spoonful to a table-spoonful of water, according 



2 Y 



