stipa penata,

Stipa

Stipas are a popular group of grasses which originate from open woodland and the prairie of Central and South America. Many have justly gained tremendous popularity in garden design as exotic-looking ornamental individual specimen plants in their own right. While the shortest are tussock grasses of around 12" (30cms) height, the tallest may reach up to 8ft (2.5m).
Common names like Feather grass, Needle grass and Spear grass are more descriptive, indeed many people people will remark on the gentle swishing sound that can be made by the taller varieties in the wind. While some varieties are so feathery-looking they are almost translucent, others shimmer in the sunlight, and there are those which are more robust-looking. Stipa are grown for their habit, and the seed heads are often the most attractive part of the plant.
Stipa do not like freezing tempertures although some will suffer cold weather for short periods, the operative word is 'suffer'. Likewise, the same applies if they are subjected to extended wet periods where their roots systems are unable to dry out appreciably in between.
Stipa arundinacea pictured above is a variety which is renowned for seeding everywhere. You can see them in their thousands skirting the plant and, in late summer it is a good habit to scoop them up by the handfull if you prefer not to weed them out individually all over your garden.
A young stipa will take about three to four years to reach the mature size pictured. At which point it is best to cultivate Stipa Arundinacea as alternate pairs or even threesomes for even better results. The reason for this is because a mature plant is best maintained on a three-year life cycle. Because by end of every third year the proliferation of dead dry stems will overwhelm your plant and it will  progressively poorer from the third year onwards unless it is rejuvenated every third year.
During the spring once the danger of hard prolonged frosts are over, a mature Stipa arundinacea is best cut to the ground. Warning: If this is done before the danger of frost is over you may well lose the plant as the protective top growth has been removed. During the summer new colourful shoots will appear, but it is not until the second sumer after pruning to the ground that your Stipa arundinacea will look its very best. The third succesive summer is OK, but not quite so good and the cycle is repeated.
By having two or three mature Stipa arundinacea and staggering their tri-yearly hair cut you will always have one example in perfect condition and one waiting in the wings.
Stipa gigantea otherwise known as the giant feather grass is the tallest Stipa at 2.5m in optimum growing conditions. Dark green stems support the charachteristic dense tufted, purplish spikelet seed heads. S. gigantea does not require the same attention as S. arundinacea, none-the-less don't hesitate to remove dead stems every year.
Stipa tennuissima is a particularly dense tufted grass, comprising as it does of very fine bright green stems. The fine stems of Stipa tennuissima which can be upto 2ft long, are both its main attraction and sometimes its downfall, the later due to the amount of winter wet that can remain trapped above the crown. Stipa tennuissima is most definitely the softest and most feathery looking of all grasses. With this plant, more than most grasses, attention to drainage will pay dividends if your location is subject to extended periods of winter wet.