Tom Coward suggests lofty spires to inspire.

Growing plants on the edge of hardiness can sometimes be a disappointment, with a lot of hard work resulting in some pathetic specimens, sulking their way to death. But gardeners do love a challenge and there are a few candidates that are so beautiful, they deserve perseverance. The past couple of winters have been mild at Gravetye and I’m excited to see that our Echium pininana plants are about to flower.

These are some of the most striking plants I know, throwing up enormous spikes of electric-blue flowers, up to 15ft tall, which are always covered in bees. As a biennial, it builds up its reserves of energy through the first season, before throwing everything it has into a magnificent display the following summer. After it sets seed, the plant dies, but, even through the following winter, its towering skeleton is a thing of beauty.

E. pininana (pictured above) self-sows quite freely and the plants at Gravetye are the progeny of a successful flowering as long as 10 years ago. Every year, some seedlings pop up and we weed around them, giving them space to develop into handsome foliage plants, but, until this year, every winter, they died off in the frosts.

Against the shelter of the south-facing wall of one of our long borders, this plant should really cut a dash and so I’m trying it in a combination with a larkspur called Cloudy Skies. I bought the larkspur seeds from Thompson & Morgan (0844 573 1818; www.thompson-morgan.com) and germinated them last September, before overwintering the plants in the cold frame. We waited until mid April before planting them out and I hope that Cloudy Skies’ airy blend of soft-blue and white will be really interesting with the Echium punching through.

As a native of the Canary Islands, E. pinniana will never really be more than the occasional bit of fun in our garden’s climate, but, in milder regions, such as along the south coast or in central London, it can reliably flower en masse.

One of the places to see it used to best effect is in the Ventnor Botanic Garden, on the Isle
of Wight. Sheltered by south-facing cliffs and warmed by the Gulf Stream, it rarely gets hit
by frost and its beautiful Mediterranean garden is one of the best examples of wild
gardening I know. With its mild climate, fascinating plant collection and charming atmosphere, it’s well worth a visit at any time of year, but when the echiums are all in flower, it’s truly out of this world.

There are about 40 different species of Echium and, although many are quite tender, several are well suited to colder gardens. E. russicum is one of the most interesting, with claret-red flower spikes, reaching about 2ft–3ft. Native to Russia and eastern Europe, it can handle some of the hardest of winters, as long as it doesn’t get too wet. It can be reliably perennial, coming back year after year, and now is a good time to sow it, to begin flowering next year.

Like all echiums, it has quite bristly leaves, which can irritate the skin, especially on a sunny day; you might want to wear gloves when handling it. However, the great advantage in this is that it makes them highly unpalatable, giving them a good chance of surviving where rabbits are a problem.

This rabbitproof quality is especially useful with the annual E. Blue Bedder, which is good for sprawling through the border and has a really long flowering season. We always make a sowing each spring and these plants can be useful to patch up any rabbit damage that may have occurred among earlier plantings.

Of all the echiums, the humble viper’s bugloss, E. vulgare, a native species, remains one of my favourites. This, I feel, is quite an underrated garden plant, with its vivid-blue spikes that fade to a purple hue. A biennial, it’s very hardy, but also drought-tolerant. It will self-sow everywhere and, although some people call it a weed, I love it. We just pull out seedlings where it isn’t wanted, but, when it flowers alongside the ox-eye daisies, it makes one of the best summer displays in the garden, in return for a minimal amount of work.