HOME GARDENS

Bay of Plenty Beacon, Volume 15, Issue 12, 20 March 1950, Page 3

HOME GARDENS

(By J. S. Yeates, Massey Agricultural College)

DRAINAGE

This season of the year is apt to make one forget the difficulties of winter and spring, when one of the major problems confronting many gardeners is how to get rid of surplus water. The planting season for most trees and shrubs is approaching however, and drainage should be seen to well in advance of planting time. Closed drains of some sort are generally more useful than open ones. The simplest closed drain is that in which brushwood is placed in the bottom and then buried.' These brushwood drains are quite useful but once the brushwqod rots, soil blocks them up and they are of little use. Manuka brushwood is generally used, because it has fairly good lasting properties. The common'* field tile, used in large numbers on fai’m land, is really the best and most permanent covered drain of all. These tiles are quite cheap, especially if the three jnch size is used. Before putting in tile drains, a few points , should be considered. First you must have somewhere to drain the water to; then you must decide how deep to put the drains, how far apart, andf how much fall you will give them. The depth of the drain is determined by several factors. 'Obviously it will not give drainage any deeper than itself. The depth is also regulated partly by the fact that the outlet may not be very low. Drains rsar the surface, drain the soil directly above them comparatively fast, but deeper drains, other things being equal, will draw moisture from further on, each side. Shallow drains can be a nuisance where' deep digging is employed. A general depth of some two feet or even more, is a good working rule. The amount of fall can be anywhere from about one foot in fifty down to as little as one in 500. A good general figure is one foot in a hundred. In a lawn or other area where a number of drains are needed, a distance of 10 to 15 feet between drains is suitable. The simplest way -to arrange the drains is‘ in a herring-bone style, with one main drain running down the jniddle of a garden, or better down a lawn, and the branch drains run•ning off at an angle on one or both sides. The junction between main drain and branch is best made with a special “Y” pipe which has a side-piece made in place. Before placing the tiles in the drain, the latter should have the bottom evenly graded and shaped so that the pipes lie snugly in the drain bot-? tom. Twist each pipe around as you fit it in place, so jthat you get a close a fit as possible, to prevent soil washing in there. If the drains are well down in very heavy clay it is a good idea not to put all the clay back on top of them, but to mix in some free draining material such as sand or gravel. / Roots In Pile Drains If you have tile drains within reach of the roots of trees and shrubs, the roots are almost certain to get in through the joints and block the pipes. That is why it is better to run the main 'drain down the centre of the lawn. If it must pass through or near to a shrubbery or the hedge, then all joints within reach of roots should be well covered with concrete. The water enters the pipes almost wholly at these joints, so that using the concrete makes the pipes almost useless for taking water from the soil at that part. The advice is frequently given to prepare good drainage for a particular bed-or plant by digging out all the subsoil to a certain depth and filling this hole with stones, bricks \and other free-draining material. Such a hole will serve only as a sump in which water will collect and become stagnent. By all means dig a hole, but see that some means, like a drain, is provided so that water can escape from it.