QBARS - v18n1 Rhododendrons Against Walls

Rhododendrons Against Walls
Alleyne R. Cook, Vancouver, B.C.

Dr. Phetteplace in his article introduced a problem which I believe has nothing to do with lime. This is the death of shrubs planted near to walls or against the sides of houses.

These deaths are caused, not by lime as is so often stated - and never proved - but by lack of moisture; at least that is what I consider.

I doubt if very many people realize just how much water is needed to thoroughly soak very dry ground. For example for ten weeks from the end of July there was no rain in Vancouver; then in one week we had two heavy thunder showers. The following weekend I had reason to open a trench across my lawn, which had had no artificial watering during the dry spell. The rain we had had, had been sufficient to make the roof gutters overflow but it had not penetrated ½ inch into the soil. Then followed a wet week; the official reading at the airport which is normally less than we receive on our mountains, was 8.5 inches. The following weekend I found that even this rain had wet the ground for barely an inch, below that, for the four feet that I dug, the ground was dust dry. No doubt by the end of the winter the soil is completely soaked but if there had been no further rain then all that had fallen during the wet week would have returned to the surface.

Around most houses there are wide eaves. This prevents most of the rain from falling on the soil directly beneath. Then there is the direction from which the rain comes. Here in Vancouver it all comes from the east and any land on the west side will be dry even in the spring. The north side, because it is shaded, is always moist; the east will certainly start the summer in good condition, while the south, although receiving a fair amount of rain, will also receive the hottest rays of the sun. Because the borders along buildings or walls are usually narrow they do not receive the regular prolonged watering from a sprinkler, they acquire it from a hand-held hose. The result is no more than a damp surface soil, never does it have a good soaking. Result, by the end of a hot summer the plants, lacking real, useful moisture, give up the ghost.

Of course it could be lime. It could also be Just about every other mineral to be found in the soil. It could be such a concentration of minerals, both those already in the soil and those that fertilizer-happy gardeners add, that it is a wonder that anything grows in these places. For in miniature these are the conditions to be found in the American desert. The water that falls dissolves the soil minerals but, because of the high rate of evaporating, these salts are brought to the surface instead of being washed through the soil as is the case along the Coast where the rainfall is heavier. Hence the alkali conditions of the desert.

But that brings us back to the lack of water given to these areas of the garden. And it also points out the danger of making a statement simply because someone else has said it.