66 PB ACTIO AL GUIDE TO GARDEN PLANTS 



end of autumn or early winter. The object is to turn up a mUch 

 greater depth of soil than can be accomplished by simple digging as 

 described above, and to loosen and leaven the subsoil. As the latter, 

 however, is generally much less fertile than the upper layer of soil, 

 care must be taken that it does not completely replace that when the 

 work is finished. Should it do so, more harm than good has been 

 done, as the fertile soil has been placed at the bottom of the trench, 

 where the roots cannot reach it ; or if they do they have to work in a 

 lower temperature, and this in itself may be detrimental to the roots. 

 Unless they work in a proper temperature, the protoplasm (see p. 22) 

 in the tender cells is unable to become active, with the result that 

 water and the food it contains cannot be absorbed. Hence the leaves 

 cannot assist in assimilating the food necessary to build up the tissues 

 of the plants and to produce flowers, fruits &c. 



Opening a Trench. — A piece of ground 3 to 4 feet wide should be 

 marked off with a line. This is dug out about 3 or 4 feet — the width 

 and depth of the trench usually correspond — and is wheeled to the 

 other end of the ground, where the work is to finish. Indeed the work 

 is laid out precisely in the same way as for digging, but there is of course 

 much more soil to remove. 



The first trench being open, the next piece of ground, the same 

 width, is marked off and dug into it. The soil, however, should not be 

 completely inverted as in digging, especially if the subsoil is poor, but 

 should be placed in the trench in such a way that it is always more or 

 less on an inclined plane. To secure this the soil from one trench may 

 be allowed to invade the other, thus keeping the worst soil always at 

 the bottom, and the best on top. Manure should be placed or mixed 

 with the lower layers of soil, which in due course will become improved 

 in texture and fertility. 



Trenching may be repeated about every third or fourth year. But 

 whenever it is done, the soil should, if possible, be trenched at right 

 angles to the direction on the previous occasion, so as to secure greater 

 distribution and change. 



The same may be said in regard to digging. If the soil is dug from 

 north to south on one occasion, it should be dug from east to west on 

 another, or in any other different direction. 



Drainage. — The necessity and importance of thoroughly draining 

 the soil used in seed pots, pans &c. have been mentioned at p. 45. 

 For the cultivation of outdoor crops, whether flowers, fruits, or 

 vegetables, the necessity for a well-drained soil is no less important. 

 Indeed the success of any crop depends very largely upon whether the 

 soil is in such a poi'ous state that water will readily pass away after 



