350 



THINNING. 



SO as to leave tlie plants wider apart than in a spring crop ; because in the 

 latter case the plants, from their nature, run very speedily to seed, producing 

 much smaller radical leaves than they do during the slow vegetation of 

 autumn. Again, a turnip crop, whether of spring or autumn, will be left 

 thicker on a poor soil than on a rich one ; because the latter will raise the 

 plants individually to a larger size, and thinner in the shade, and late in 

 autumn, than at midsummer, in order to admit of the wider spreading of the 

 leaves, to compensate, by breadth of surface exposed to the light, for what 

 the season is deficient in solar brilliancy. It will readily be conceived that 

 crops that have few or narrow leaves and perpendicular roots, such as the 

 onion, require less thinning than such as have broad- spreading leaves, such 

 as the turnip ; and that those which have tap-roots, like the carrot, do not 

 require so much surface soil as those which have spreading roots, and creep- 

 ing or trailing shoots, such as the New Zealand spinach. Thinning seedling 

 herbaceous plants may take place at any season ; but when they are to be 

 cut out with the hoe and left to die on the spot, dry weather and a dry state 

 of the soil should be chosen ; and when they are to be pulled up by hand, 

 or taken up by the roots with a tool for transplanting, a moist state of the 

 soil and cloudy or rainy weather are essential, in order that the fibres may 

 receive as little injury as possible in parting from the soil. 



782. Thinning plantations. — Timber trees when planted in masses are 

 placed much closer together than they are intended to be finally, partly to 

 shelter one another, and parti}'- to profit by the trees which are to be from 

 time to time thinned out. By planting moderately thick, the nutriment con- 

 tained in the soil is much sooner turned into wood than it would be if only 

 the few trees were planted which are finally to remain ; and by these trees 

 standing near together they are drawn up with straight stems, so that the 

 timber produced, even by young trees so treated, is of some use. By increas- 

 ing the distance between these trees by thinning, the source of nourishment 

 to the roots of the trees which remain is increased, and the space round the 

 branches for light and air enlarged, so that by degrees, with every successive 

 thinnng, larger timber is produced. At what time the thinning of a planta- 

 tion ought to commence, how long it ought to be continued, and at what 

 distances the trees ought finally to stand, will depend on the kind of tree, the 

 kind of plantation, the soil and situation, and the climate. In the case of a 

 plantation where the object is to produce straight timber, the first point to 

 determine is the probable height to which the kind of tree to be planted will 

 attain in the given locality ; and then to obtain from the experience of others, 

 or from observation of natural woods in similar localities, the distance 

 required to enable a tree to attain that height. A tree in a sheltered valley 

 and on deep rich soil not much above the level of the sea will attain double 

 or triple the height which it will on a hill at a distance from the sea ; the 

 temperature in the latter situation being much lower, the soil generally 

 poorer, and the wind greatly stronger. The subject of timber plantations 

 not forming a prominent feature in this volume, we shall only add that 

 experienced planters have laid down certain rules for thinning timber planta- 

 tions, and that the best of these we consider to be those of Mr. Cree, published 

 in the Gardeners Magazine for 1841, and applicable to every situation from 

 the level of the sea to an altitude of 1800 feet. Supposing the height which 

 the trees in a plantation of round-headed kinds are supposed to attain is 

 eighty five feet, and that they have been planted at the distance of about 



