Alpine plants that enjoy life in a pot

Press, 3 September 1982, Page 7

Alpine plants that enjoy life in a pot

Gardener's W diary i

Derrick Rooney

An alpine plant which has been flowering unusually well and early, having presumably enjoyed the cold, dry winter, is the old hybrid saxifrage, “Jenkinsii." This is a gem of a plant. It belongs in a group of the large and complex saxifraga genus known as the Kabschia section, which consists of small plants with tiny, needle-shaped leaves. They form hard, mossy or silvery domes, and in early spring are often smothered with relatively large. shortstemmed’ flowers.

There is a large number of Kabschia species and numerous natural variants, many of them from Eastern Europe, but for garden purposes the best are the hybrids which are of British origin, or which came to us via Britain.

"Jenkinsii" is one of these. Its date and place of origin are unknown, and its parentage is in doubt, though various experts have speculated about it.

The little mound of foliage is very dense, silvery, and mossy, and the flowers are a wonderful, soft, dusty pink. Other Kabschia have flowers ranging iff colour from near-red to white and several shades of yellow. I used to grow several of them, including the lovely deep yellow “L. G. Godseff," but gradually they faded away, and only a couple now survive. Some died of heatstroke, some were chewed up by grass grubs. Unfortunately none of them is any longer readily obtainable from nurseries. They included plants with charming names, such as

burseriana. “Haagii." and "His Majesty." I did have "His Majesty” again last year, but there is, no sign of it now. I suspect it has once again gone to the great compost heap in the sky. Probably if I had grown it in a pot as I now do with .“Jenkinsii". I would still have it, because these little alpines are among the few plants which seem to thrive better when potted.

The advantage of growing them in this way is that you can move them about to seasonally suitable places without interfering with their root systems or disfiguring parts of the rock garden with ugly arrangements of shadecloth or panes of glass. Many alpines, and the tiny saxifrages are among them, like cool, shady conditions in summer and dryish, sunny ones in winter. English books recommend growing plants under deciduous trees as one way of achieving this. But in our climate it is nearly impossible, when plants are under trees, to give them enough moisture in summer. Pot culture in a shadehouse is sometimes effective, but what I have found, and I am sure many other amateur growers have found, is that a shadehouse which is just right for summer tends to be too dark and humid in winter.

Recently I hit on what seems to me a happy compromise — I stripped off the wooden slats from half of my shadehouse roof, and replaced them with nylon-rein-forced polythene glasshouse cladding. Now I have, in effect, two

climates in the one structure — a cool, slatty side through which any natural rainfall can reach the plants, and a warmer, drier side on which the plants receive a lot more light. The saxifrages at present are on the second side. As well as "Jenkinsii” there is Saxifraga grisebachii, a wonderful tiny alpine which belongs to a different section of the genus, known as the “encrusted" group.

There are several encrusted species, so called because of the hard bumps and ridges on their foliage. All are from the Adriatic region, and differ mainly in the colour and hairiness of the inflorescences. Grisebachii is the cream of the cream in this group. It is beautiful at all times. While growing it forms a hard, silver rosette, only a few centimetres across, with perfectly arranged leaves against which limy encrustations make a geometrical pattern. In late winter a glowing, molten red area develops in the middle of each rosette which has reached flowering size. As the days lengthen so does the flower stem. At first it is erect, flame shaped; as it grows taller the tip bends, like a shepherd's crook. Fleshy, softly hairy leaves emerge on the flower stem; extraordinarily, these are bright red or hot pink. The tip of the inflorescence is decorated by large, deep red bracts. The flowers themselves are small, and dull pink. Most of the colour comes from the stem leaves and bracts. Because of its slow growth

and the difficulty of propagating it other than by seed this saxifrage is seldom seen in nurseries. I was lucky enough to get a pinch of seed three years ago. Though I have had to be patient with it — the largest of my seedlings, which is flowering now. is a mere six centimetres across — it has not been difficult to raise in pots. One or two small seedlings planted out on the rock garden have disappeared. One saxifrage which does do well in the open is the plant sometimes grown under the name “Saxifraga macedonica,” and sometimes as "Saxifraga juniperifolia." The two names are supposedly synonymous, and are listed as such in the “RHS Dictionary of Gardening.” Visually the plant grown in New Zealand keys out as Saxifraga juniperifolia. But Royton Heath, the panjandrum of English rock gardening, says quite categorically in his classic “Collector's Alpines” that the key distinguishing feature of Saxifraga juniperifolia is that the leaves, when crushed, smell of juniper berries. This kind of information may mean nothing, or very little, to a taxonomist. To a gardener it is invaluable. So I put a sprig of my plant to the test — rubbed it.

scrunched it, sniffed it. No scent. Thus it isn't Saxifraga juniperifolia. and it can't be S. macedonica because that doesn’t exist. So what is it? It is a very high-class little alpine with bright yellow flowers which come out so early that even in my garden they are almost over. After I have trimmed off the spent flower stems in a few weeks time it will revert to a tiny, hard, mossy green bun — the very epitome of a high alpine. Unlike the others in the Kabschia section, to which it belongs, it is very easy to grow on the open rock ..garden. I say this with hesitation, because one of the first lessons I learned when garden-

ing was the unwisdom of being dogmatic about plants. If I have a saxifrage growing in sun, someone will score with it in the shade. If I find it needs a dry place, someone will grow it wet. So I will say only that Saxifraga macedonica, or whatever it is called, was one of the first plants in my rock garden. While most of its compatriots have departed, it is still there, it is still a hard, green dome that grows imperceptibly bigger each year. And it is on the driest, hottest, and most arid ledge. Its companions are a rugged little silver-leaved, pink-flowered thyme from Spain, and small irises from the sun-baked Aegean slopes. They have a very happy mixed marriage.

In a cooler part of the rock garden, in a dampish spot, if such could be said to exist this year, is Saxifraga vayredana, one of the species of the “mossy” section. This is a choice alpine strangely neglected by nurserymen. none of whom has listed it for sale as far as I know. I have it only because it turned up in a batch of mixed saxifrage seed; it has not been at all difficult to grow. In three years (it is the same age as my grisebachii but has spent its time outside) it has made a low mound perhaps 20cm across. The foliage is bright green, almost fleshy, hard-looking but quite soft to the touch, it rises like a mini-Ayers Rock from carpets of raoulla and mazus.