Gentian that provides special challenge

Press, 11 May 1984, Page 10

Gentian that provides special challenge

Gardener’s ! DIARY

Derrick Rooney

Among the surplus plants which my extended rock garden has soaked up are several spring gentians, which I described recently; but these are not the only gentians I have planted. A number of other see-

dlings, if they survive and grow, will extend my gentian season through summer and late into autumn. One will continue the season into early winter. To provide a challenge, there is a choice but cantakerous named variety for mid-autumn.

This is “Caroli,” arguably the most beautiful of the autumn gentians; in the sino-ornata mould, but finer in stem and in leaf, it has large trumpets of the clearest and most vivid cobalt blue. There is no other gentian quite like it.

The parents of “Caroli” are fine species in their own right: Gentiana farreri, which bears the name of Reginald Farrer, the “father of the English rock garden,” and G. lawrencei.

Neither of these is available commercially in New Zealand at present, though they do crop up occasionally in the seed lists of the specialist societies. Gentiana farreri is, by all accounts, a good-tempered and easily grown species, more vigorous than G. sinoornata, and with deeper blue flowers. G. lawrencei, which I have not seen, is described as having pale sky-blue flowers and a week constitution.

Alas, "Caroli” has inherited the beauty of farreri, though the lighter tones, and the constitution of the other. It is a weak plant, difficult to establish and more difficult to keep going, in the intense, dry heat of Canterbury summers.

I have lost “Caroli” several times, and I accounted it a great triumph when I kept it going in my rock garden for two summers.

After that plant went I had to live without “Caroli” for a couple of years, but a chance conversation in a bus in South Canterbury in the autumn led me to a Geraldine nursery, where the owner, a great producer of horticultural rabbits from his magician’s hat of a shadehouse, sold me another.

In the planting of this “Caroli,” I have taken a lot of care, because I am not keen to lose it again. It has the sun it needs, but some shelter from a large sandstone boulder, and a southern exposure which may help to keep it cool in the summer.

The soil is a gritty one, but also contains plenty of organic matter: very old black sawdust, and soil from the hen-run where poultry have been scratching and doing other things.

Some alpines would find so rich a diet indigestable, and a few years ago I wouldn’t have fed gentians on it but a very good grower in Timaru, who has thriving clumps of species which spend miserable and sickly lives in my garden, told me recently that the secret of growing good autumn gentians is to give them a rich soil.

I suspect, too, that regular division and replanting in fresh soil in spring would help to keep them healthy.

“VIP” is another autumn gentian in my extended rock garden. This is what horticulturists call a “grex,” i.e. a hybrid strain, raised from seed and producing plants which closely resemble each other. “Caroli,” which is propagated by division, is a clone.

The “VIP” gentians are small, neat plants which make tight, leafy clumps and do not sprawl about like the Asiatic group to which sino-ornata and “Caroli” belong.

The flowers are a bit smaller, but are an intense deep blue, shaded green in the throat, and face straight upwards on stiff stalks about their own length.

If they have a fault, it is that the flowers open only on warm days, and as there are not too many of these in May, most of the late flower buds are wasted.

So much for autumn. There are gentians for summer, too, and I have finally found a home for several which, raised from seed a year or two ago, had been languishing in my plunge beds.

One of these is a delightful little thing called Gentiana cruciata. Everything about it is small: leaves, stems, and flowers. I have grown a small clump in the main rock garden for a year or two, and liked it so much that I wanted more.

Its mature height is only a few centimetres, and the flowers, bell shaped with sharply folded-back corolla tips, are intensely blue.

I’m not sure that I have the right name for it, because Gentiana cruciata is described in the main reference books is a much larger and coarser plant with tiny flowers. But in the meantime, I haven’t anything else to call it.

Gentiana siphonantha and Gg. freyniana and lagodechiana are largely summerflowering gentians which are not, however, too big for the rock garden. The former is, I think, Chinese, and has large (eventually; like all gentians, it is painfully slow to seed) baal rosettes, along the lines of those of the more familiar European Gentiana gracilipes. In midsummer leafy flower spikes appear, and shoot up about 25cm before the deep violet flowers appear.

The other two belong to the same group as a wellknown summer-flowering species, G. septemfida, and differ mainly in their size (which is smaller) and in perhaps having fewer flowers to the stem.

Both are a good, deep blue, though of course, their flowers are smaller than those of the autumn group. Gentiana scabra and G. makinoi, two Japanese species, complete my gentian extensions — temporarily, perhaps, because these may well be better placed in’ the herbaceous border, near the front.

Their height, in the humid Japanese climate, Js listed as 30cm to 40cm, but in our drier summers they may remain more compact.

These are among the species which have been hybridised in Japan to produce a number of named garden plants; I did acquire one of these, some years ago, but it lived a short life and in my garden the nursery which supplied it never listed it again. I forget its name.

I hope the species may prove more permanent. Both are leafy plants with scrambling stems which like, if they can, to ramble among other herbage. Their flowers are, naturally, blue.