Home & People

Press, 6 December 1979, Page 14

Home & People

One of the first lessons I learned about growing bearded irises is that they dislike animal manure. I was warned against using the stuff in my early days of gardening, by an experienced iris grower, but when I acquired several great heaps of manure, all beautifully composted with sawdust, I threw caution to the winds, and mulched heavily on, and around, the irises. Result: magnificent growth and, the next summer, twice as many flowers and a big increase in the size of the flowers. Aha, I said, as I heaped more of the stuff around my irises, the experts are wrong again. But I had overlooked Newton’s law, and by the second summer my action was beginning to have an equal and opposite reaction. There were few flowers, growth was poorly, and the plants were riddled with leaf spot. Only now, after two years with no feeding except the annual dressing of superphosphate, are these irises beginning to recover their old vigour. They had been, I am convinced, suffering from indigestion. The irises in this group are all old varieties, no longer listed in the iris catalogues, and if I were a

really keen iris grower would scrap them. But I cannot quite bring myself to do it; they are still growing, undisturbed, in the same spot where we found them, halfchoked by waist-high cocksfoot, when we began remaking this part of the garden four years ago. That is the great virtue of these old, cast-iron plants; they will tolerate all sorts of neglect, cope with competition, and go on making a display regularly, year after year. On the other hand, there is a lot to be said for the newer irises, too, for while few of my more recent acquisitions have the vigour of the old “toughies,” they have introduced a wider range of colours, and they do have flowers with more shape and “substance.” They are worth making a bit of a fuss about, and I am doing just that, preparing a special bed to accommodate a few bearded “treasures.” These are mostly small irises, growing 15in or less high. I find them more interesting than the tall types, partly because they do not get bashed about by the wind, partly because they are more challenging (they are not difficult to grow, but they are not easy to grow well), but mainly because they are early risers.

Some of the smallest bearded irises begin to flower in September, when there is not much about in the garden except primroses and bulbs, and the work done on them by hybridisers in recent years has carried their season right through to summer; there are now dwarf irises

that still have an occasional flower when their big brothers are chest high and beginning to flower. Now is a good time to transplant them, and over the next week or so I shall be moving a large number of mini-irises into their new bed. This bed is a slightly raised area, once planted in rhubarb but invaded by twitch at some time in the distant past, and adjoining the rock garden, to which it is now connected by a border of mosry boulders. The twitch is dead, thanks to that wonderful new spray, “Roundup,” and I have gone to some trouble to raise the soil a few

more inches and to cultivate it to a great depth. The irises will not have it all to themselves, because a whole border of irises would be a wonderful sight for a few weeks, then a dead bore for the rest of the year. I shall ring in a few foreigners among them, mini-shrubs like ericas and callunas, perhaps an alpine or two, and a few winter-flower-ing bulbs to make the whole year interesting. Fortunately, all these plants like the sort of environment I am trying to provide: rich, humusy soil (lots of compost or leaf, mould but no manure), good drainage, especially sharp drainage around the collar, and an aspect that is sunny but not parched and sunbaked. My iris bed begins with a layer, a foot or more below the surface, of semi-composted, strawy litter from the hen-run, with an admixture of blood and bone. By the time roots reach it, it will be thoroughly decomposed. Above this, well chopped up with the rotary hoe, are the remains of the twitch and rhubarb; these are covered, in turn, by the “clean” topsoil. To replace the uppermost layer of humus, which is now buried, I have worked a mixture of very old, rotted sawdust, neat, and pea gravel into

the top two or three niches, along with a good dressing of superphosphate and potash.

This should do two things: provide a cooling surface mulch. and encourage rapid root growth (and consequently rapid establishment) after I fill it with plants. Other than this, there is only one requirement for the successful establishment of a new iris bed: firm plantingThe old roots die after bearded irises have flowered, and as the rhizome elongates the plant grows a new root system. This is why plants received from nurseries in early summer often appear to have no live roots. So long as the rhizomes are planted firmly, to make very good contact between the growing point and the soil, new roots will emerge very quickly after planting. The depth of planting varies with the soil. In my light, sandy loam, which is free-draining and has a high silica content (after a day’s weeding I have no tips on my fingers), the small irises do best if planted with the rhizomes about an inch below the surface. In heavy soils, shallower planting would be advisable.

GARDENER’S DIARY

By

Derrick Rooney