During the course of a fairly long garden life, I have often heard gardeners express surprise.
When some of their own native plants are transferred to their gardens, they stubbornly refuse to respond to any kindness.
Rhododendron Albiflorum
While visiting America recently, I learned that Rhododendron albiflorum, from British Columbia and the Pacific Northwest, is one of the most difficult rhododendrons to settle down in captivity.
In fact, it seems to be equaled only by the perversity of trailing arbutus (Epigaea repens) on the eastern seaboard.
On the other hand, very few New Zealand gardeners can get their lovely white Ranunculus lyallii to grow in cultivation.
Native Alpines
We in the British Isles have the greatest difficulty with some of our native alpines, such as Primula scotica and our form of Loiseleuria procumbens.
Some of the reasons are obvious, such as great differences in exposure, air density, moisture, and other factors.
If these differences were not almost unsurmountable, Rhododendron albiflorum would grow as well in Seattle gardens as in the higher reaches of the Olympics.
Epigaea Repens
Epigaea repens carries its own bacteria to manufacture its food, but why should the similar Epigaea asiatica from Japan prove more amenable, if not entirely an easy plant, in gardens?
Ranunculus lyallii is even more peculiar, as it does not grow at a particularly high altitude. Although a plant of the bogs, those conditions can be imitated.
Cornus Florida
Cornus florida, the eastern United States flowering dogwood, is a case in point. In Scotland, it grows like a weed, but it very, very rarely flowers.
At that, only an odd bloom is produced because of summer and fall’s lack of solar heat to ripen the wood.
Yet the western dogwood (Cornus nuttallii), coming from a moister and cooler climate, is very successful and flowers as in the Pacific Northwest.
Feijoa Sellowiana
One of the oddest cases of success with a plant is that of Feijoa sellowiana, which is such a popular hedge plant around Santa Barbara in southern California.
I was told that this had been tried many times in Oregon and Washington gardens and never very successfully.
Yet we have grown it for 25 years against a wall in eastern Scotland where it flowers almost every year but never fruits.
It is never covered in winter and has never been cut by frost, although I have known the soil in which it is planted to be frozen hard more than a foot down.
Hydrangea Quercifolia
Why should this plant of the sub-tropics succeed with us and fail in a milder climate? It is possible to quote many other examples.
Why should your lovely Hydrangea quercifolia prove to be a very tender plant with us?
Yet Rhododendron timberlandense, that pretty little azalea from very nearly the same area, be at home and remain uncovered all winter?
Amount Of Acidity In The Soil
In other cases, the soil’s acidity accounts for success or failure. It is, of course, well known that all Ericarear, almost without exception, dislike alkaline conditions.
What is not so well known is that certain groups of rhododendrons prefer a certain acidity in the soil, while others grow much better if the soil is less acidic.
There is reason to believe that the lovely but difficult Rhododendron lacteum will thrive better in almost the maximum acidity, near ph 4.5.
In other cases, the soil’s acidity accounts for success or failure. It is, of course, well known that all Ericarear, almost without exception, dislike alkaline conditions.
What is not so well known is that certain groups of rhododendrons prefer a certain acidity in the soil, while others grow much better if the soil is less acidic.
There is reason to believe that the lovely but difficult Rhododendron lacteum will thrive better in almost the maximum acidity, near ph 4.5.
On the other hand, Rhododendron rubiginosum and its allies definitely prefer nearly neutral soil.
In this way, scientific research is helping us master the successful cultivation of what used to be considered difficult plants.
When I was young, plants were classed as hardy and not-hardy, two expressions that covered a multitude of meanings.
Today we are a little more careful about using such generalizations.
44659 by E. H. M. Cox