Cobaea pringlei

A hardy herbaceous perennial relative of the familiar cup-and-saucer vine, C.scandens. Having white flowers, it's not as spectacular as its tender purple-flowered relative but still a lovely thing. I grow it in a sunny spot on a well-drained but rich soil, with a thick strawy mulch in winter just to be on the safe side. It dies down completely in winter.

Once it gets going it's a big plant capable of covering quite a large area in a single season so make sure you put it somewhere where it can roam free. It tends to start late and flower late too so provide warmth and shelter.

Despite the bindweed-like roots it does not spread vigorously and can be slow to propagate. As a result I never have enough of these to satisfy demand so please enquire.
£12

Asphodeline taurica

As much a foliage plant as one grown for its flowers. The plant makes very eye-catching rosettes of extremely narrow pale grey leaves, complemented by a spike of slightly rosy white flowers in summer. A very tasteful species needing excellent drainage and full sun £8

Herbertia lahue

A gorgeous little summer flowering Iris relative producing attractively marked violet flowers on short stems just above the ground. Although this is widely distributed in the USA it’s of doubtful hardiness and may need protection, but I recommend trying it in short turf – a technique that works remarkably well with many ‘tender’ bulbs

£6

Callirhoe

I have no idea why these American mallows are not much more widely grown

Callirhoe digitata

One of the best plants I sell – a very slender 4ft tall upright species with extremely narrow glaucous leaflets and stems. Intense wine pink mallow flowers are produced over a long period in summer.

Hardy and adaptable but best grown among low-growing plants as it doesn’t seem to cope well with competition
£7

Callirhoe involucrata

An amazing species – I have no idea why this isn’t very very popular. Produces long leafy stems that trail out over several feet in all directions and up into neighbouring plants producing a sprinkling of intense pink mallow flower all summer.

In winter it retreats back to a compact buttercup-like cluster of leaves and the old stems can be cut away, so not even slightly invasive

£7

Pelargonium sidoides - the true species

A remarkable low growing species with silver/grey leaves and black, honey-scented flowers. It is hardy enough to be grown outside in the southern UK, given a sunny, sheltered, freely drained spot. In 2010 it lost its leaves but came back as strongly as ever to flower late summer and autumn.

It seems most of the 'sidoides' in cultivation in the UK are hybrids (probably with P.reniforme) and have wine purple/maroon flowers. The easy way to tell is that the hybrids have main stems and make a  bushy plant much like many popular 'scented leaved' pelargoniums with the flowers on side branches.

Sidoides on the other hand has no stems at all - the leaves are on long petioles arising directly from the base of the plant. The flowers are on very long (up 40cms), extremely slender stems which also arise directly from the base and radiate out horizontally. The flowers are very close to true black with no hint of purple or pink. Once you have seen the two together the difference is obvious.
£8

Sida hermaphrodita

A tall leafy mallow with clouds of small pure white hibiscus flowers.

An easy hardy prairie perennial for any good soil

£8

Dichroa febrifuga

An attractive but tender evergreen woodland shrub with conspicuous heads of pink (or on lime-free soils, blue) star-shaped flowers followed by metallic vivid blue berries - overall very like Hydrangea macrophylla but without the sterile florets.

Apparently most of the plants in cultivation are hybrids between the true Dichroa and Hydrangea macrophylla, but none of the Hydrangea's cold tolerance seems to have found its way into the progeny. Strictly speaking should probably be classified in Hydrangea

Sadly not hardy enough for most UK gardens but worth a try in very mild sheltered sites and will regenerate from the base if cut down by frost - probably not soon enough to flower though. Otherwise a splendid plant for a cool greenhouse
£16