Exotics standing up well to winter frosts

Press, 11 July 1980, Page 7

Exotics standing up well to winter frosts

GARDENER’S DIARY

Derrick Rooney

Some tender exotic shrubs have been standing up to the cold surprisingly well this winter. One of them is the so-called “In* dian hawthorn,” Raphiolepis “Delacourii,” which is nipped at the tips in most winters,, but at present is flowering in winter for the first time in my garden, in spite of frosts that have seared some of its neighbours. This shrub is a hybrid member of a genus of evergreen Asiatic ■ shrubs belonging to the rose family, and closely related to the more popular photinias. They are not hardy in the Northern Hemisphere, but grow well in most lowland areas in New Zealand. There are several species, but the only two likely to be encountered are Raphiolepis umbellata, which is fairly hardy, and R. indica, which is tender. “Delacourii” is a hybrid between these, and a better garden plant than either.

It makes a mediumsized, twiggy bush, with leathery leaves, and when it is doing well every branch is tipped with clusters of rosy pink flowers. These are not unlike hawthorn blossom, but are larger; and the petals are fleshy. “Delacourii” gets its flower colour from the second parent, because R. umbellata has white flowers. The few reference books that list these plants describe them as needing light, leafy, or peaty soil, but I have my doubts about this, because I have seen “Delacourii” growing — and flowering — very well in sticky clay.

My own plant has grown very slowly in my light soil, and although it is several years old it is scarcely more than knee high. But it is struggling for moisture and nourishment against fierce competition from several large trees and an old hedge. I promise myself every spring to move it to a well favoured site, but I never seem to get around to this. After flowering the bush always has a few juicylooki'ng blackish berries,

covered with bluish bloom, but there are never enough to make a show. One shrub that is looking very frost-battered, though I hope it will recover, is the “Mexican loosestrife,” Heima salicifolia, which comes from Central America, but from a fair altitude, and is hardy in Christchurch. This is not a showy plant, but is what is termed a “plantsman’s shrub.” Its strongest appea’ is to the collector of rarities. Actually, it is quite pretty throughout summer, when it has a succession of small, dish-shaped yellow flowers, which are succeeded by tan-coloured,

woody seed-pods, closely set oh the twigs and resembling little birds when unripe, but opening out like tiny crowns. The leaves are pale green, and willow-like; the habit of the bush is upright; and the growth is dense, with a lot of thin Light brown bark peels attractively from old stems. Heima salicifolia makes a sft bush in a few years, and I fear it may, like many fast-growing, softwooded shrubs, be shortlived. Copious quantities

of seed are set, but none has germinated for me. Summer cuttings root readily, however, and fortunately I have one potted up in a frame in case the old fellow fails to pull through the winter. Another Mexican plant wearing a punished look after the June frosts is Beschorneria yuccoides. This is a big, fleshy perennial rather than a shrub, and its tongue-twister of a name disguises a very desirable plant. The general appearance is of an overblown yucca, but whereas the yucca is in the lily family beschorneria is an amaryllid — and thus is related to daffodils. Established clumps flower in early summer, sending up 2m spikes of green and red flowers on shrimp-coloured stems. It may be a while before I see any of these, because the central rosette of my three-year-old plant, which was approaching flowering size, has since the frosts had the glassy look that goes before collapse. There will probably be regrowth from the base in spring, but it will be touch and go whether it reaches flowering size before another run of frosts cuts it down.

So far, there is no sign of frost damage to another yucca-like Mexican amaryllid, Furcraea bedinghausii— a plant usually dismissed as far more tender than beschorneria. This furcraea is a plant for patient gardeners as well as lucky ones, because it is difficult to establish (though it grows hardier as it grows older)

and takes many years to reach flowering size. Beschorneria yuccoides has stemless rosettes, but the furcraea develops a short, massive trunk, thicker than a man’s body. The plant usually dies after flowering.

The inflorence is not very colourful, but compensates for its lack of brilliance by sheer bulk — and by eccentricity, because although it is capable of setting and ripening seeds in the normal way it is also viviparous, i.e/ it bears “live” young in the form of tiny plan-

tlets that appear all over the flower stem as it begins to fade. In warm climates these just fall to the ground and take root, but here they must be detached, potted up, and grown on under shelter until they are large enough to be planted out in early summer. Two more Mexican plants showing surprising cold tolerance this winter are the Montezuma pine and the Guadalupe cypress. Both have a hardiness rating of HB, which means they should be unable to tolerate frosts below about -sdeg. but neither has shown any sign of damage in a run of frosts that included

several of -8 deg. on the screen. The cypress, Cupressus, giiadalupensis, is found only on the island of Guadalupe. It resembles the familiar macrocarpa, and appears to be similarly wind and drought resistant, but is slightly smaller and less sombrelooking. Its only really notable feature is the bark which flakes off exposing a bright reddish undersurface; I am pruning my plant, as it grows, to have a clear trunk, thus emphasising this feature. Montezuma’s pine, Pinus montezumae, is the most common pine species in Mexica, and has numerous varieties whose hardiness depends on the altitude at which they were collected. It is rare in cultivation, but is arguably the most beautiful of the pines, and there is reason to suppose it to be hardier than the better - known weeping Mexican pine, Pinus patula. Montezuma’s pine has long, bluish - green needles, carried in fives. The bark i-s corky, reddish brown, and deeply and irregularly fissured, so that it presents a rumpled appearance. The tree is capable of growing to 100 ft, but is a slow starter. My plant made no progress at all in its first two years but put on a spurt last autumn, and trebled its height in a couple of months. Last year, in a relatively mild winter, it suffered a check and lost most of its needles, but thus far the more severe frosts this winter have made no impression on it.