Add architectural interest with restios

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from SFGATE.com

Erle Nickel
Sunday, April 25, 2010
(Restios are available now at sloat garden center)

One increasingly popular way for gardeners to add texture and form to their gardens these days is through the use of grasses. The range of choices is extensive, but as the availability of South African plants continues to expand, adventurous gardeners are discovering a group of bamboo-like plants named restios. Members of this diverse family (Restionaceae) range in height from 4 inches to 10 feet and resemble a graceful cocktail of grass, rush, bamboo and horsetail.
In the absence of leaves, restios’ vertical stems, called culms, take over the job of photosynthesis. Restios may not have leaves but they are decorated with papery leaf sheaths that cling to the culms like parchment, providing an eye-catching pattern of tan and greens, silver-grays or glaucous-blues.

Restio’s petite flowers are displayed in summer spikelets and held in inflorescences at the tip of the culms. The arching seedheads, showcasing coppers, bronzes and golds, offer a soft crown to the clean vertical lines of the restio culms. The combination is both breathtaking and elegant.
One of the best and most adaptable evergreen restios is R. quadratus, featuring distinctive, thick square culms. Reaching 6 feet in height, it forms a striking clump of architectural foliage when mature. Even the young canes are attractive, featuring luscious, soft-green feathery foliage.
Restios fit nicely in a Mediterranean planting bed and can be used as a tall border or to add architectural interest. These tough, adaptable plants make dramatic potted plants and are spectacular in the margins of water features.

Restios at rest
The most widely cultivated of restios is Elegia capensis. It is also one of the most beautiful, branched in attractive whorls encircling the culms, reminding some of a more elegant horsetail. Chondropetalum tectorum features slim culms topped by spiraling, dark inflorescences. Its compact, tufted form shimmers like fiber optic reeds in the breeze. Thamnochortus insignis are tall, reed-like tussocks whose rose-colored feathery male flowers produce pollen in such large amounts that female bees hover around all day. Cannomois grandis is a beautiful, large restio whose culms have persistent reddish-pink sheaths and drooping hair-like foliage.

Cultivation
Restios are best grown in full sun in well-drained acidic soil, requiring regular water to get established then less as plants mature. Restios are used to minimal phosphorus in their homeland so use nitrogen-based amendments. Protect rhizomes from extreme cold with location and thick mulching. These are low-maintenance plants, with only the occasional cleanup needed. Mature plants can be divided in the autumn but take care to disturb the roots as little as possible. R. quadratus is hardy to 20 degrees.

Pests & diseases
Restios are generally very durable plants but can suffer the occasional mildew.

Availability
Several of the restios mentioned here will be featured at the Merritt College spring plant sale. You can find selections at full-service nurseries. To view restios in their full mature glory, check out the nearest botanical garden.

Erle Nickel is a nurseryman, gardening writer and photographer who cares for a sprawling Oakland garden. E-mail him at enickel9@live.com and check out his blog at normsnursery.blogspot.com.

This article appeared on page L – 3 of the San Francisco Chronicle
Read more: http://www.sfgate.com/cgi-bin/article.cgi?file=/c/a/2010/04/25/HOCO1CU15J.DTL#ixzz0mFqDCVP3

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