Elspeth Thompson on cultivating pennisetums, the fountain or foxtail grasses

• Ask the Expert archive

Some plants call out to be touched, and fluffy pennisetum grasses are certainly one of the most tactile. Last year I grew a large specimen of P. setaceum in a pot by the front door at our seaside house and few people, myself included, could resist giving the soft, furry flower-heads a stroke on the way in and out. Sadly, I no longer have it. I forgot that it was not fully hardy and lost it to frost when absent in London - a foolish and expensive mistake.

Known as fountain or foxtail grasses, for their graceful arching form and brush-like inflorescences, pennisetums are among the most eye-catching of the ornamental grasses that have become fashionable in recent years. Seduced by plumes in subtle shades from near-white through bleached straw, pale pink and bronze to deepest purple, particularly when backlit by the low late-summer sun, many gardeners take them home from the garden centre, only to lose them, like me, because they have not positioned them properly or given them the protection that some need over winter. So here, in the spirit of promoting these lovely plants yet preventing further casualties, is a guide to getting the best from them.

Pennisetum alopecuroides is the hardiest of the bunch, usually around 2-3ft tall with superb foxtail plumes. Look out for 'Cassian's Choice', with its bronzy heads and orange autumn leaves, and smaller varieties such as 'Hameln', with bleached white plumes and 'Little Bunny' which, at 8-12in high, makes a great edging plant. In the right soil (see below), these should survive outside all year. Pennisetum orientale is hardy to 23F (-5C) and so has rightly become more popular with our recent run of warmer winters; 'Karley Rose' is a newish cultivar whose pink flowerheads may catch your eye. And then there are the more tender types: P. setaceum and its purple offshoots now classified as P. x advena; lovely P. villosum, whose particularly fluffy cream seedheads are hard to resist; and spectacular P. glaucum 'Purple Majesty', often grown as an annual for its chocolate-coloured leaves and bulrush-type heads that turn from gold to purple.

All pennisetums need a warm, sunny spot and, crucially, good winter drainage. If you are planting them in open ground, where they mix well with other grasses, such as the stiffer, more upright Calamagrostis x acutifolia 'Karl Foerster' and spiky, strappier plants such as phormiums and yuccas, you can give them a good start by digging plenty of grit into a large planting hole. Don't even consider them in a north-facing bed with heavy clay soil prone to waterlogging in winter, as even the hardier types will rot. Pennisetums also look great interwoven with the electric-violet heads of Verbena bonariensis, fiery sparks of scarlet and orange crocosmias or cactus- head dahlias in shades from dark black-red through tawny orange to lemon. Just remember that the more tender types (make sure to check when you are buying) will need to be dug up, planted in pots and brought under cover before the first frosts.

One way of avoiding this kerfuffle is to plant your grasses in containers. I started doing this a couple of years ago out of necessity - building work was imminent and I did not want them disturbed - but frequently do it on purpose now. Grown in pots, pennisetums can be given the exact soil and conditions they require, and when winter comes they can simply be shifted into a greenhouse or sheltered corner. Their habit of sulking until early May makes them ideal for under-planting with spring bulbs - the emerging leaves will hide the dying foliage of daffodils and species tulips. When in full flowering sail, they can be shunted into the spotlight and arranged among other potted star performers such as cannas, dahlias and black- eyed-Susans. In early autumn, they can be placed where the low-angled sun can shine right through them and light up the panicles like fibre-optics. Most importantly of all, perhaps, growing pennisetums in pots raises them so those gorgeous soft plumes can be seen, and touched, all the more easily.

WHERE TO SEE AND BUY

All of the above varieties and more are available mail order from Knoll Gardens near Wimborne in Dorset (www.knollgardens.co.uk, 01202 873931), whose beautiful show gardens are open to the public Tuesday to Sunday, 10am to 5pm (or dusk if earlier) until November.

BOOK TO BUY

The Encyclopedia of Grasses for Livable Landscapes by Roger Grounds (Timber Press £40) is a hefty but lavishly illustrated tome full of information on all the main grasses and their cultivars, with chapters on designing with grasses, working with texture, light and colour, keeping less hardy varieties, and growing them in containers.

To do this week

For crunchy and colourful winter salads, sow radicchio now in open ground in full sun. 'Rossa di Treviso' is one of many varieties available from Seeds of Italy (020 8427 5020; www.seedsofitaly.com). The green leaves turn red in cold weather and will be ready for picking from November.

For the best blooms on canna lilies, pictured left, and annual bedding plants that are still flowering, give them a feed with general fertiliser at every watering and dead-head at least every other day.

Make new strawberry plants by severing healthy-looking runners (or plantlets) that have rooted close to the parent plant and lifting them with as large a root ball as possible. Trim the young plants of damaged leaves and plant in pots, pictured right, or in open ground, with at least 16in (40cm) between plants.