Grasses & Flaxes – where the wind blows
New Zealand – clean and green, not to mention windy! In conservation terms, our wind is something we can be proud of.
It’s a planet-friendly renewable energy resource and we own some of the best. With global warming, the prediction is that our weather is going to get even windier. It’s just as well then, that kiwi gardeners are a hardy lot, well used to blustery conditions. So, for that matter, are our plants.
Basically there are two ways to deal with wind. Create shelter, or plant wind tolerant plants. For human comfort, and that of any delicate plants we may wish to grow, shelter is a huge priority.
The best kind comes not from walls, but living shelterbelts and hedges, which slow the wind down without creating turbulence. Wind hardy New Zealand natives ideal as shelter include pohutukawa, karo (Pittosporum crassifolium), Corokia and Olearia. Fast growing NZ Ngaio (Myoporum) provides good shelter for slower growing trees. If space allows plant extra wide shelter. There is no need to stick to just one variety.
When shelter isn’t an option (as is often the case when a great view is at stake) there are plenty of wind hardy plants to choose from, especially among NZ native plants, which have evolved to cope. A good spring blow will whip the flowers from your blossom trees, bowl your delphiniums, shred the leaves of palm trees and burn tender Japanese maples to a crisp, but it will leave grasses and flaxes standing proud. In fact these highly textural beauties look all the more dramatic in motion. On a windy site, an entire garden mass planted in flaxes and grasses is easy-care and easy on the eye. It’s also an extremely attractive way of integrating architecture into a natural landscape.
Fabulous Flax
Few other cold hardy plants come close to providing the form and texture of New Zealand flax.
All round the world, it’s in hot demand as an exotic garden treasure. At home, flax is so rich and plentiful, as iconic as the pohutukawa adorning our natural landscapes, that it’s easy to take it for granted. But with the many colourful varieties and more compact growth habits than ever before, flax tops the list of favourites, for gardeners and landscape designers alike.
Of the two main flax species, Phormium tenax (harakeke) is the tallest, with stiff upright leaves over two metres and flower spikes up to five metres tall. Phormium tenax great for swampy ground is inclined to suffer from shredded leaves in heavy wind. The real wind lover is Phormium cookianum (wharariki), 1 to 1.5m in height, with either weeping or upright foliage. It thrives in dry wind-swept coastal and mountain climates.
The smaller flax cultivars are popular for mass planting or as accent. Dark plum coloured “Platts Black” grows about 1m tall. The bronze edged leaves of “Surfer”, a compact 60x60cm variety, have twisted tips giving the plant a wave like effect which increases with maturity. “Jester” is a stand out with bright red, pink and green stripes. “Cream Delight” has a broad central band of cream and a deep red edge. Pinky red “Evening Glow” is aptly name and a vibrant accent among green foliage. Compact all-green cultivars such as “Green Dwarf” and “Emerald Green” are very prolific in their flowering and at less than a metre tall, a good choice for those who want the natural green look in a small space. The beautiful golden yellow flowers are great for picking. In early spring, the tuis flock to them with reckless abandon.
For best foliage colour and healthy compact growth, plant flax in sun. Generally, the cookianum types prefer drier soils, which is why they do so well on windy sites. Avoid very sheltered locations if you want to minimize pests such as scale insect and mealy bug. Most varieties are fairly frost hardy. If damaged by frost they will generally bounce back if you refrain from removing frost burned leaves (which protect the younger inside leaves) until the frosty season has passed.
To keep flax tidy, cut old foliage cleanly from the base with a sharp knife. Coloured flaxes can sometimes revert to plain green or bronze growth, which should be removed before it takes over. Lifting and dividing every few years also keeps plants looking fresh and yields new plants for the garden. Dig up the entire plant then prise it into sections, breaking the roots if need be – flax is tough! Trim long or damaged roots. Trim the foliage to a fan shape, replant and water well.
Graceful grasses
As tough as they are beautiful, ornamental grasses meet a multitude of uses. Plant them around ponds and swimming pools, as ground cover or edging, in pots, or mass plant with flaxes on windy banks.
Ever-moving grasses sparkle in the light and contrast superbly with broadleaf plants, or anything solid, e.g. stepping stones, paving, sculpture, architecture or chunky architectural succulents. A huge colour range (golds, yellows, oranges, browns, reds, creams, blues and greens) offers great scope in garden design with fluffy flower heads a seasonal bonus.
New Zealand‟s own native grasses are world famous, but we also have beautiful imported grasses at our disposal. There is a grass for almost every situation – shady or sunny, warm or cold, wet or dry. The most important thing is to choose a grass that‟s right for the location without being too invasive.
The spectacular native tussocks such as Carex comans, Carex testacea are excellent for windy coastal sites. Wind tolerant tussocks for moist coastal soils include Carex trifida and Chionochloa rubra. On really wet ground Carex secta is superb. Blue or silver foliage often points to dry tolerance. Bright blue native, Festuca coxii forms a compact, finely foliaged clump, about 35cm high. Tall and elegant Helictotrichon, or “Blue Oat Grass” is a moderately frost-hardy and drought tolerant grass which looks especially good in a pot. Great for cold climates, blue tussock (Poa colensoi) grows just 25cm tall with fine, tightly rolled leaves. But this grass needs plenty of air circulation, and is not one for humid climates.
Shade tolerant Anemanthele lessoniana (Gossamer Grass) is mainly green in shade, but a sunnier location becomes beautiful reddish gold. Rosy red, feathery flower stems add extra appeal in summer but they are prone to self-seeding so best removed once the display weakens. Other grasses for shade are Carex „Evergold‟, Carex morrowii and Carex solandri.
Compact Chionochloa flavicans forms a tidy 1m clump with flower stems up to 1.5m. The elegant drooping flower heads, lovely for picking, change from gorgeous shimmery green to silky cream in autumn.
It pays to be wary of the beautiful grasses we see in overseas gardens. Some of them are problem weeds here and often not available for that very reason. Among the most beautiful of the well-behaved exotics are the Miscanthus varieties with their eye-catching autumn flower heads. Miscanthus zebrina (zebra grass) is a tall deciduous species with the additional attraction of gold striped leaves. Elegia capensis from South Africa is a tall rush like plant with beautiful brown paper sheaths up its stems and russet flower heads, but this big perennial forms very dense clumps up to 2m tall so needs space. Smaller growing E. cuspidata has rich bronze flower heads in papery bracts and rarely exceeds a metre.
Although grasses are generally very easy-care, it’s a myth that they are maintenance-free. In less than ideal conditions they can turn shabby after a few years. The most important thing is to choose a variety suited to its location. Native tussocks from windy alpine climates with gravelly soils won‟t take to kindly to high humidity and rich soil. In warm subtropical climates exotics grasses such as mondo grass and Lomandra are more likely to last the distance.
A little pampering, especially at planting time, will help grasses give their best.
Those that prefer dry conditions benefit from grit or gravel being added. Grasses that need some moisture benefit from added compost. Water and weed newly planted grasses until they’re well established.
Groom grasses in spring, using a gloved hand to ease out dead foliage. Untidy or deciduous grasses can be cut back close to the ground and will come away with renewed vigour in spring. Lift and divide every few years to keep growth fresh and vigorous.
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When should flax be trimmed?
You can trim at any time. Make sure you dont cut the heart of the plant just the outer and older leaves and not the middle 3.