“I told you so”: these plants fall into this category (bear with me). They are not restrained, they are more than rambunctious, and they are capable of being troublesome if you leave them to dictate their own party. However, they will thrive in those areas in which more gentle sorts will wither away. They are useful: they like to spread, blanketing the soil and covering up tricky spots, taking on any weeds in their wake, and even feeding neighbouring plants. But at some point, you will have to take them on, so for that future point, I did tell you so.
Shady spots are limiting because of the obvious lack of sun, but plants also have to compete with the roots of trees and large shrubs. They need to be happy with the thin layer of top soil or beastly enough to muscle with the other roots. Two comfreys are able to do that: Symphytum Iberian, Iberian comfrey and S. tuberosum, tuberous comfrey. The former is a little smaller, growing up to 30cm high, and makes an impenetrable weed cover among shrubs and trees. The flowers start off burnt orange in bud and open to creamy yellow buds, though some open to pale blue and even pink. S. tuberosum has pale yellow flowers and grows taller, up to 60cm high. Both are considered mineral accumulators, feeding the plants around them with goodness mined from deep below. Shear back the leaves after flowers to encourage neat, young foliage.
Another shade-tolerant type is Geranium nodosum, though it will happily tolerate full sun, too. Whatever you give its feet to wander in, it will flower all summer with lovely lilac-blue flowers sitting just above the smooth, mid-green maple-shaped leaves. It will self-seed as much as it will spread, but it’s such a pretty thing, it’s hard to mind.
Persicaria amplexicaulis and its many cultivars will tolerate a wide range of soils in sun or light shade, and look wonderful with grasses. The slim, tall, dark spikes of red, or various hues of pink flowers, bloom all summer long until the frost puts a stop to them. I like ‘Rosea’, one of the gentler pink cultivars that can weave a garden together. If you are on very damp soil, try the red bistort, P. bistorta ‘Hohe Tatra’ with fat spires of pink, orchid-like flowers.
Finally, for those dry, barren soils that nothing else will touch, try Euphorbia cyparissias, the Cypress spurge. It rapidly forms dense carpets of cheerful, sulphur yellow umbels in spring above blue-grey mounds of foliage and then dies off in autumn in a blaze of orange. It will also tolerate some shade; the cultivar ‘Fens Ruby’ looks particularly good next to dusky hellebores.
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