Evergreen ferns are priceless gems in a winter garden. During summer, it’s easy to take our subtly variegated green backcloth of leaves for granted but we come to crave it during the long, grey days of winter.

We often associate ferns with damp, shady places where few other plants would deign to grow. But many ferns can handle sunny spots as well. One of Scotland’s three native evergreen ferns, Common polypody, Polypodium vulgare, grows in full sun on one of my old dykes. Over the many years I’ve seen it the fern has steadily spread to form a large clump, along side several other specimens.

While it basks contentedly in the summer sun, its roots have found soil between cool stones. A short fern, the leaves spring singly from creeping rhizomes to form horizontal loose clumps. It stays green throughout winter and alongside its moss and lichen companions, it makes the dyke a fascinating and beautiful habitat in the dark months.

You find many ferns growing in the archetypal damp shade because of their complicated reproductive system. They produces spores, usually on specialised leaves which, in some species, can be decorative. These spores disperse and develop in to a small, simple structure, called the prothallus, which may look like a liverwort. Male and female organs develop on the underside and the sperm released from the male organ swim through a film of water to reach a female organ, usually on a different prothallus.

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And that’s the point. The prothallus needs to be in a damp place. After fertilisation a new fern plant rapidly develops. So the mature plant will tend to be somewhere that has been damp at the time when the prothallus was developing and maturing.

Two of our other naive species are evergreen as well and will flourish in a garden. I’m lucky enough to also have Hard Fern, Blechnum spicant, sometimes known as herringbone fern. It has leaves with thin, widely spaced leaflets, technically known as pinnae, that grow to about 50 cm.  They grow in tufts but the rhizomes often branch to form clumps of several crowns. They develop as dense clusters of leaves looking like one large clump. This fern prefers more acid soils and dislikes clay and naturally grows in quite open habitats such as moorland.

Hart’s Tongue, Asplenium scolopendrum, usually grows in lowland, often limestone areas but will grow over granite near the sea. If growing in the garden it will appreciate a handful of seaweed meal each spring, which I at least do, to compensate for being an hour’s drive from the sea. Slightly unusually, its fronds are not divided but are leathery looking, to about 50cm. Older leaves are dark green but the young spring growth is pale almost translucent.

But there’s also no shortage of cultivars for many spots in the garden. Polystichum Shiny Holly Fern, is perhaps one of the most striking. Its large, deep green shiny fronds are stiff enough to stand up to what winter throws at them.

Plant of the week

Betula ermanii 'Blush’ is a species of birch tree with most attractive creamy white to blush pink bark. The tree has an open habit and the trunk often divides into several stems displaying even more of the bark.

It is wide spreading and best grown as a specimen tree when it offers plenty of opportunity for plants that tolerate summer shade to grow underneath.