Pennisetum is a broad genus of tufty clump-forming herbaceous perennial grasses. They’re grown mainly for their foliage and bring grace and contrast to borders with their flowing movement and fluffy flowerheads. They are available in varying shades and sizes and work well in borders, patio containers or gravel gardens. Naturally, they thrive in sandy, poor and very well-drained soils, making them very well suited to coastal gardens. They’re not fully hardy and in areas with very cold winters they will likely need frost protection.

How to plant

— Pennisetum are supplied as bare roots in spring for planting between February and May. They must be planted soon after delivery and can't be stored for long. If you can't plant on the day of delivery, remove the roots from the packaging within 1-2 days and place in a bowl of water outdoors to soak, then plant within a week.

— All bare root ornamental grasses should be potted up and grown on for some time prior to transferring into borders.

— Soak the roots in water for 3-6 hours prior to planting. Pot into temporary 2 litre (or 15-20cm diameter) pots, using a good quality multi-purpose compost with added grit to aid drainage.

— Plant with the roots fully submerged in the compost. There will be some old foliage from the previous year which is cut at around 10cm. This should be left exposed above the soil surface. New shoots will emerge from the base of these dried stems.

— Grow them on in a sheltered spot outside or in an unheated greenhouse. They can be transplanted to suitable growing positions after 2-4 months or once growth is established and the plants easily come out of the temporary pots with the soil held intact by the roots. When you see roots starting to emerge from the drainage holes in the bottom of the pot, it is an indicator that the plant is ready to be transplanted.

— When they’re ready to plant into the garden, choose a position with well-drained, gritty, stony or sandy soil. Dig over the area first to aerate the soil and remove any weeds. The area should be in full sun.

— It is recommend to add multipurpose compost to the planting hole when planting, this will add nutrients to the immediate area and provide a soft medium for new roots to grow easily.

— Position your your plant into the hole and backfill the hole with soil. Firm down after planting, ensuring the base of the stems remain level with the soil surface. Water thoroughly after planting.

— Penniseum look great and grow very well in patio containers. If your ornamental grass is intended to remain in a patio container, you can plant the bare root directly into the patio container with fresh multipurpose compost, there is no need to pot up and grow on first in this instance.

— As with all young plants, monitor your newly-planted Pennisetum for pest damage and remove any excess growth from neighbouring plants in the border to reduce competition.

— This perennial is half hardy, tolerating temperatures down to around -3/-5C for short periods in free-draining soil. In colder areas, they should be protected from frost with mulch, fleece or grown in containers so they can be moved to shelter for winter.

— Water-in after planting and keep hydrated when in growth, particularly during the first year. Once fully settled in, they prefer quite dry conditions.

— Bare root grasses will have some dried foliage from the past year still intact. Pennisetum supplied in late spring will have some pale shoots which have already emerged. The shoots will soon start to green up after planting, watering and being exposed to daylight, additional new shoots will also emerge through May, June and July.

Aftercare

— Pennisetum foliage changes from green to a beautiful hay colour as the summer season progresses. You can cut back the foliage in late autumn or early spring to around 10cm above soil level. This makes way for fresh growth which emerges again in spring. In colder areas, it is recommended to leave the old foliage intact until the following spring because it helps to insulate the crown of the plant over winter.

— Pennisetum forms a clump over time and the display gets better every year. Clumps that have become too large and dense can be dug up and split in half or quarters with a sharp spade in early-mid spring. Each piece can then be planted separately.

— Choose the sunniest position available with very free draining gritty or sandy soil.

— If cutting back the past year’s growth in spring, be careful to avoid cutting the tips off the new foliage as it is emerging.

Read further general instructions about planting bare-root ornamental grasses