In search of new and interesting conifers

Press, 5 August 1988, Page 10

In search of new and interesting conifers

wardener’s W DIARY

Derrick Rooney

I’d like to put in a plea today for some “new” conifers — not “new” in the sense that they are absolutely spanking fresh, but in the sense that I haven’t come across them before, or haven’t previously realised their value. A few years ago I disposed of a lot of scruffy or boring conifers, vowing never to replace them. But no gardening decision should be irrevocable.

Changes in the garden and the discovery of a few better varieties changed my mind — well, a little bit.

A few weeks ago I wrote about some groupings using columnar conifers — “Greyswood Pillar,” “Swane’s Golden,” and so on. Another to dome my way since then is the golden form of the Chinese juniper — Juniperus chinensis “Aurea.” Juniperus chinensis is one of the parents of two favourites of Americans

and local authorities, “Hetzii” and the various "Pfitzeriana" clones. These are crosses with J. Sabina, which, according to some authorities, is not even a juniper. They would have it revert to the genus in which it was placed for a while in the nineteenth century before someone decided it should revert to the name given to it by Linnaeus in the eighteenth century. If they are right, it should

be called Sabina officinalis. .

No-one is suggesting that J. chinensis is anything other than a juniper. As a wild plant this grows in both China and Japan and varies a lot in size and habit. The biggest forms grow as tall as 20 metres, but garden forms are much smaller. “Aurea” is very compact, and grows in a narrowly columnar form. Almost always it has a characteristic mixture of scale-like adult and prickly juvenile foliage. It gains height at the rate of 20 to 30cm a year and after 10 years is usually less than a metre across.

This treasure came from Cedar Lodge conifer nursery, near New Plymouth. Mrs Noeline Sampson, who runs the nursery with her husband, David, says this is one of the few coloured conifers that need semi-shade — it tends to burn in summer sun. I think I have just the place for it, under a maple. Conifers generally need full sun, but some are

remarkably tolerant of abuse. While clearing away some undergrowth recently I came across a suppressed plant of a small, globular conifer which must have been almost entirely deprived of sunshine and nourishment, but looked remarkable fresh and green. I could tell by the smell that it was a Thuja and I racked my brains for a while about it. Finally I remembered having acquired, some years ago, a small plant of a variety called “Caespitosa.” This is a cultivar of the American “arbor-vitae” or white cedar, T. occidentalis. The admirable Humphrey Welch, whose book “Dwarf Conifers” is the bible of all those interested in these plants, describes “Caespitosa” as a very slow growing plant which forms a low, hemispherical bun, wider than it is high. The shoots are either flattened or twisted, so that an old bush has a shaggy-dog expression. It is, says Mr Welch, an attractive form which should be better known. What was interesting to me was that when I dug it out of its barren resting place all the soil fell off the roots, revealing that the lower stems had rooted into the mulch. I was able to divide it into two shapely little bushes, which are re-establishing in planter bags while they await a permanent home.

Several of the smaller conifers lend themselves to propagation in this way. One is Cryptomeria japonica “Vilmoriniana,” one well-known miniature globular form, which for several years I used to lift annually, cut into pieces, and replant as several new plants. The cryptomerias are not often planted in Can-

terbury, mainly because they prefer a more humid climate, but some of them have impressive survival skills.

Back in April, on the way home from a conference in Dunedin, the party I was with stopped in Geraldine to get cuttings from the lovely specimen on the edge of the domain there. This is a very tall tree with an extremely elegant and exceptionally narrow form. I carefully packed my cuttings in a damp plastic bag, and on arrival home tossed them in the refrigerator. I’ll deal with you tomorrow, I said. Early last month I finally got around to planting them. They were still fresh and green after a winter in the dark. ,

The tray they share with a mixture of other conifer cuttings is in the open at present, but I will put it in a frame when the days get warmer and I think it safe to make room for them by potting up some of last autumn’s shrub cuttings. The cryptomerias may not root after that treatment and if any do I will regard that as a major bonus. Really, I don’t recommend this treatment for any cuttings.

All cuttings should be planted as soon as possible after being taken — except for fleshy succulents, which are apt to rot unless the cut surface is allowed to dry out for a few days. If I am taking shrub cuttings on a hot day I usually carry with me a bucket of water, into which I drop the cuttings as soon as they are severed from the parent. Usually I don’t take conifer cuttings at this time of the year, but I have this lot on the basis that cuttings should always be accepted when they are offered — even if it isn’t the optimum time for them.

Many commercial growers take the bulk of their conifer cuttings in July and August, but they are putting them in mistbeds with bottom heat. I have only a cold-frame, and have found autumn cuttings best for conifers and for some other shrubs, such as coprosmas and hebes.

A wider range of ornamental shrubs may be propagated from JanuaryFebruary cuttings. Hydrangeas, for example, grow like triffids from January cuttings.

A final conifer note: chamaecyparis thyoides “Ericoides” is one of those mystery plants whose origin and parentage are both unknown. Since it is a fixed juvenile form with no adult foliage it is next to impossible to make any taxonomic decision about it, and at various times it has been put in Ch. pisifera and even into Thuja orientalis.

A dense, pyramidal bush, it grows to about 1.5 metres tall (but this would take about 15 years) and is always soft to look at and touch. Its summer colour is grey-green, its winter colour violetbrown.

I’ve always ranked it with those “interesting” plants that one might grow if one had room — for everything. Recently, however, I came across an exciting selection called “Red Star.”

.In its winter uniform, when I first saw it, this conifer was a glowing ma-hogany-purple, with a dash of pink, on the sunny side, and violet on the shady side. In summer, I imagine, it will return to the usual grey-green, but in winter it practically vibrates.

Temporarily, it is located in what I call my wallflowers frame — the one where I keep all those lonely plants that I cannot bear to throw out but for which I haven’t yet found suitable partners. Before spring is out I am determined to find a slot for “Red Star” in the garden, even if I have to dig out something else to make room for it.

‘Conifers generally need full sun’

‘ln winter it practically vibrates’