With Chelsea Flower Show days away, my thoughts have been turning to the show’s Great Pavilion and one of the most original large collections of plants under one roof. The nurserymen and women who bring their plants to the show, some from all over the world, also bring years of expertise, and a willingness to share their knowledge. Here are just a few I’ve come to value as plants I can rely on, thanks to the expertise of the Chelsea exhibitors.
This is nowhere near as widely grown as it should be. It is elegant (the common name is bowman’s root) with small, star-shaped white flowers – followed by interesting seed heads that persist through winter – held on very thin, wiry stems, and handsome, finely toothed trifoliate leaves that display superb colour in autumn, turning a deep red. The fine foliage and stems complement the golden inflorescences of the low growing woodland grass Deschampsia cespitosa “Goldtau”, one spilling through the other to great effect. G trifoliata slowly makes a plant of around 1m high and 50cm across, its best position near the front of a border, or in a naturalistic or cottage garden or woodland edge planting, ideally in shade and in fertile, neutral to acid soil.
This grass has featured heavily at Chelsea in recent years, no doubt partly because it flowers in June and, as a result, requires little manipulation for show gardens and pavilion exhibits. A native of the Mediterranean basin – I’ve seen it growing wild at altitude in the High Atlas, where it clings grimly to whatever humus-enriched niche in the rock it can find – the adaptations that make it a success in the wild also make it a great garden plant. A low clump of fine, grassy foliage – in the windswept mountains keeping low prevents excessive transpiration and reduces the risk of being ripped out of the ground – is topped with slender, arching, wand-like stems carrying golden, oat-like inflorescences to a height of around 1.8m-2m. The whole effect is one of translucent shimmering gold, and the combination of height without bulk means it can be used much further forward than plants of similar height but greater bulk. Christopher Bradley-Hole used it to devastating effect in his 2004 Chelsea Garden, Hortus Conclusus, where he combined S gigantea with shrub roses. It excels as a repeated feature plant, in open, sunny gardens, where it can draw the eye back and forth through the garden.
Allium hollandicum “Purple Sensation”
Tiered displays of Allium are one of the highlights of the Floral Pavilion at a number of stands, including Broadleigh Bulbs, Jacques Armand and WS Warmenhoven. Thankfully for the growers, most are flowering at around the time they would normally do in the garden. I rate them for two reasons; they are exceptional value for money – at less than £1 a bulb for most cultivars you can afford to plant them in big numbers with massive impact – and because, although they are transient, a month or so in flower usually, the seed heads persist into winter and make a strong architectural statement. At Harlow Carr, the RHS garden in Yorkshire where I was curator, we planted 5,000 “Purple Sensation” in the main borders, using them in large drifts through clumps of later flowering perennials. In smaller numbers Allium can be planted in clumps as a focal point. I’m growing A “Ambassador” and A “Gladiator” at home for the first time this year, in groups of seven and eight bulbs to create vertical accents through my borders. “Gladiator” should be especially rewarding, with an eight-week flowering time.
Euonymus alatus “Compactus”
The combination of handsome foliage and tightly compact form make this a useful background plant, giving it similar qualities to topiary pruned shrubs. This enables it to be used in a similar way, as a focal plant, or to mark the end of a border or junction with a path, or simply to provide a rhythm to a planting through repetition. For all these reasons it is an excellent shrub to plant alongside herbaceous perennials and grasses – it just seems to go with them. In autumn it moves into the foreground in a blaze of pinkish red colour, the longish, lance shaped leaves droop and the colour starts to form between the leaf veins, slowly spreading through every leaf until the whole plant is lit up. Euonymus alatus “Compactus” seems tolerant of full sun and partial shade, preferring a rich but well-drained soil. And it is genuinely compact, growing to a height and spread of around 1.2m-1.4m.
Having first seen this plant at Chelsea, I got to know it very well when I ran the RHS garden Hyde Hall in Essex. In 1969, the first owners of the garden, the Robinsons, had planted six crowns of Eremurus robustus (foxtail lily) in a west facing border of old shrub roses. They have done rather well in the intervening 43 years and there are now more than 650 plants, forming a display even more impressive than those in the pavilion at Chelsea, where the Avon Bulbs display is often a highlight. Their stems rise up to 2.5m from a basal clump of grey green foliage, the top 1m or more smothered in tiny, pinkish white flowers that are a popular food source for bees. The sight is spectacular, if short-lived – three weeks is about as much as you can hope for before the flowers fade, leaving the tall stems to wither slowly. These are steppe plants, from the Tien Shan and Pamir mountains, and the trick to growing them is to provide a deep root run of well-drained soil but to plant the roots (which are thick and fleshy and look rather like a starfish) shallowly, with the crown almost above soil level, in a warm and sheltered spot. Though tall, they have no physical bulk, so are ideal for growing through other plants, such as shrub roses, or underplanted with a bulb such as Allium, or a flowering perennial such as Salvia “Caradonna”. Hybrid Eremurus such as “Pinocchio” and “Cleopatra” offer a more compact alternative to E robustus.
Amsonia tabernaemontana v salicifolia
This looks too dainty to be able to survive the rigours of a mixed planting, the eastern blue star bears clusters of pale blue starry flowers during summer and long, delicate foliage held on fine, wiry stems. It turns a lovely buttery yellow tinged with orange in autumn (when it’s easily mistaken for a small shrub, such is the intensity of the colour), which then gradually fades to the colour of old straw. The whole plant is compact at around 90cm by 80cm, and although it takes a while to become established, it is very long lived once happy. It remains relatively scarce in gardens, which is a shame, not least as it will take a fair amount of shade. I’ve planted it in north-facing borders and, providing the site is open with some reflected light, it will do very well, associating beautifully with the bronze fronds of the fern Dryopteris erythrosora.
Paeonia “Cardinal Vaughan”
Tree peonies have a long history in horticulture. They were a favourite of Chinese emperors more than two millennia ago and are still highly desirable, and often highly priced. Paeonia “Cardinal Vaughan” is one of the easiest of the tree peonies to grow and so a great plant to cut your teeth on. Flowering in April to May, it has sumptuous, almost water lily-like blooms in papal purple with conspicuous yellow centres. Slowly it will reach a height and spread of 2m by 1.8m. If you want to know more about these beguiling plants, Kelways Nursery, which celebrated its 160th anniversary last year, has been exhibiting at Chelsea for decades and has specialised in peony and iris throughout.
Chelsea Flower Show, May 22-26