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Friday, 6 December 2013

Ornamental grasses in the garden

Ornamental grasses can be used as fillers or specimens, border plants or background plantings, as ground covers or screens, or they may be grown as container plants. Their adaptability and subtle beauty make them perfect companions to flowering plants and other woody ornamentals.

This beautiful fountain grass (Pennisetum setaceum 'rubrum') thrives in warmer, drier areas and threatens many native species and has been declared as a Category 1 weed in South Africa and although it is beautiful, I have since removed it. Other Category 1 weeds are Spanish reed (Arundo donax), pampas grass (Cortaderia jubata, C. selloana) and tussock-grass (Nassella tenuissima, N. trichotoma)


Grasses can be used in the landscape just like perennials, but their usefulness extends far beyond that of a normal perennial. Grasses are useful for erosion control, space barriers, wildlife shelters, winter interest, as a background to flowering plants, and as architectural features, to name a few.


Grasses add the dimensions of sound and movement to the garden as wind catches and rustles the leaves. The dried stalks of many grasses remain upright for winter interest. The wide variety of colours, sizes and growth habits of grasses assures that one will fit almost any garden.


The term ornamental grass is used to include not only true grasses (Gramineae) but also close relatives such as sedges (Cyperaceae) (Carex), rushes (Juncaceae), Liriope, hardy bamboos (particularly the genus Phyllostachys), and others. The flower spikes (also known as inflorescences) can be found in different shades of maroon, red, pink, silver, white, yellow, or beige and are excellent for drying.

Ornamental grasses are not the kind of grasses that you broadcast spread across the front or back yard. Hopefully, you will never run across them with the lawn mower, either. Rather, Ornamental grasses are decorative. They look great in the flower garden. They are used to add depth and texture to highlight rock gardens or if they are mixed amidst shrubs.



Ornamental grasses add grace and motion to the garden with strap-like foliage that sways in the gentlest breeze. The fluffy flowers and seed heads on many varieties last throughout the winter, attracting birds and adding winter interest to the garden.

Silky grass in the middle of winter

Ornamental grasses include many species with different textures, sizes, colours, and flower forms. Each grass species has it’s own unique form. They may form low compact mounds, tall screens, or densely spreading mats. The foliage colours include various shades of green, blue and red, as well as variegated varieties having red, white or yellow foliage banded with ivory or yellow stripes. In the fall, the spring and summer colours change to hues of red, beige, or brown, providing a great winter garden accent.


Ornamental grasses fit into the herbaceous (non-woody) category of earth’s vegetation and they are divided into two categories: cool-season and warm season. As the name suggests, cool season grasses make their best growth during the spring and autumn and usually become dormant or semi-dormant during the heat of summer. Feather Reed Grass and Blue Fescue are prime examples.
Warm season grasses make their best growth during long summer days and go dormant during the winter. The popular Maiden Grasses are examples of warm season grasses.


SELECTING GRASSES
The selection of available grass cultivars is ever increasing. One will find a wide range of height, spread, colour, and flowering times available. Some grasses have become invasive in some areas, have been declared noxious weeds and have been banned from being grown in home gardens. Again seek the advice of a local garden centre before planting grasses.
One of the two key things to consider when selecting a grass is it’s height.

Tall (2m or more), upright growing types create visual interest, especially when used towards the back of a border. Their bold lines break up space over a long season, some remaining attractive well into the winter. These are the big guys! Plan their placement carefully because you won’t be able to move them easily!

Zebra grass - The foliage develops distinctive golden horizontal bands in midsummer. In autumn, silvery-white plumes appear and last up to two months. Zebra grass can grow to 2m or taller (Miscanthus sinensis 'Zebrinus') (4-7 ft. tall).

Medium-sized (60cm to 2m) grasses may be effectively massed together, particularly in gardens with a low maintenance emphasis. Spring-flowering bulbs combine well with these for early season interest. These grasses also can be used a specimen plants throughout your garden without taking up too much space.

Low-growing (less than 60cm) grasses are ideal for edging around shrubs or combining with spreading evergreens. When mass-planted, they will form an attractive low-maintenance groundcover.

BAMBOOS
Bamboos are also grasses; they are made stiff by the presence of silica in their stems.  Often overlooked by homeowners, bamboos are a nice evergreen addition to the ornamental grass palette. There are two types of bamboo:  running bamboo and clumping bamboo.  Running bamboos can be quite invasive; therefore it is important to plant them in an area in which they can be contained or where their running habit is an asset, not a detriment.  Clumping bamboos do not spread; they form clumps. Bamboos are usually evergreen and therefore provide good winter interest.

SITE SELECTION
Most ornamental grasses reside in full sun, having spent most of their existence in savannahs or coastal plains. They don’t need copious amounts of rainfall or watering to exist and can easily survive extended periods of drought.

It’s best not to grow grasses with high water-dependent plants as either the grass will struggle with excessive moisture or the water needy will suffer from not enough. Group ornamental grasses with succulents, cacti and grey-foliage plants for their best rate of survival.

PROPAGATING GRASSES
This is by far one of the easiest plant families to propagate after succulents. The most effective method is via collecting seed and distributing in situ. The problem with grasses is not their ability to propagate but that they are so successful at it. You may find yourself weeding more often if you don’t want them to spread beyond their boundaries. In order to prevent reseeding, harvest the flower heads before they’re fully dry.


ORNAMENTAL GRASSES IN CONTAINERS
Growing ornamental grasses in containers is a great way to feature grasses without the worry of them spreading or taking over the garden. Here I've planted some Restios (Chondropetalum tectorum) in a tall pot. This grass can form a huge clump, spreading up to 1.5m in width if left unchecked.

Restios (Chondropetalum tectorum) next to my garden path - soon I'll either have to re-route the path or thin out the Restios.

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