Discover the extraordinary world of ferns

I've just bought yet another fern with an unpronounceable name. It's just as well nobody ever comes to the garden, otherwise I'd have to try saying some of these names out loud. It's our fault, of course, as it was we who carried out the christenings. The fern, which managed perfectly well for four hundred million years without a name, is blameless.

In every respect, ferns are blameless. The latest, labelled Thelypteris decursive pinnata (see what I mean?) is not listed in The Plant Finder, and it took some trawling through books (much more satisfying than Google) to discover it's now got another ghastly name, phegopteris. Poor thing. But the trawling was necessary, because I needed to know where it grew in the wild before I could decide what conditions it might like in the garden.

It comes from eastern Asia, from Kashmir to Taiwan, and this moment is probably its best: fresh pale green fronds erupting from a very small growing point. But there must be almost a hundred gorgeous fronds there, each elegantly poised to push on to the 80cm mark. More are still unfurling with that curious Zen backflip that is so much a part of a fern's grace. There is no such thing as a dud fern. Flowers? Who needs them? Gardeners soon learn that a rich, pleasing plot comes from plenty of good foliage. Flowers are the extras.

Many ferns, including this new one, will be happiest in dampish soil with some shade. Here, in the West Country, we can do damp. Damp is the way of life. Shade can be found, too. So I spent a happy evening wandering round with the fern in its pot, roots hanging out of the bottom in a way that no nurseryman ought to allow (it was one of the reasons I snatched it up – it was bone-dry and desperately needed more living room), considering various options.

Under a hazel, where it would join lily of the valley and Solomon's seal? Further up the garden, in the shade cast by the big arching branches of Rubus tridel 'Benenden', where it could grow alongside the erythroniums that have finally condescended to stay with us? Up by the hammock house, between blue-flowered brunnera and fancy primroses? Or shall I just pot it on and keep it by the door where I can get to know it as much as it will let me? Certainly, I'd have every opportunity to admire it there. It can't stop me doing that.

In town gardens, which often have rather a lot of shade – all those tall boundaries keeping other people's lives out of your own – ferns are superb, giving that gulp of soft green that is so necessary in an environment governed by hard surfaces.

Tree ferns have become trendy favourites, but they dictate a style in a way that the more lowly ferns do not. Tree ferns never look at home among herbaceous plants. They demand bananas, spiky astelias, cordylines and all the other accoutrements of the boy-kit garden.

The new fern will be number 44 in what (if I were a collector) I might call our collection. But I'm not into that particular mind-set. I am always drawn to good foliage plants and on the rare occasions when I'm cruising about a nursery with a bit of spare money in my purse (the fern cost just £4.99 – a bargain), ferns seem to speak to me more beguilingly than anything else.

But ferns could easily seduce you into collecting, because without any prompting, they do such silly things. They grow tassels like bunches of parsley at the end of their fronds. They subdivide wildly to make patterns as complex as the delta of the Nile.

A seemingly sensible, law-abiding fern such as the hart's tongue, with a plain green, strap-shaped leaf, will suddenly flip its lid and perm its edges into a series of frilly curves, or try out a black stem instead of a green one. As each permutation arose, the Victorian fern fanciers wrote out a fresh tag, bolting an extra descriptive bit of botanical Latin on to the existing name.

Ferns tend to creep up on you slowly, but once they've got you, you are lost. That's no surprise: they are so graceful, so architectural, so cool. They do not tug at your skirt as you pass by. They just get on with being ferny. They might be designer darlings, but it won't go to their heads.

Symmetry is built into every fern's soul. That is what gives them such grace. They are stayers, too. Although not technically evergreen, the hart's tongues give an evergreen effect, for the old, strappy leaves survive all through the winter until the new fronds begin to unfurl. Then – as with all ferns – you should cut away the old foliage so that you can enjoy the extraordinary drama of the new ferns unfolding. The shapes are New Age ballet.

Some ferns are meatier than others. The common polypody (Polypodium vulgare) is the sort of fern a child might draw: a midrib with leaflets sprouting along it at regular intervals.

Its cousin, P. vulgare 'Cornubiense', comes from Cornwall and is much more complicated. The frond of the common polypody is never more than about 8cm wide. 'Cornubiense' makes a much broader frond, each leaflet or pinnae subdividing into further sections and overlaying each other quite densely. Its new fronds grow in late July (which is useful) and it peaks in August, when other greenery is getting tired.

I have it growing with cyclamen and the fresh green fronds are at their best as the cyclamen start to flower. Humus, added as a mulch in autumn or spring when you are planting, will encourage all ferns to flourish.

See asplenium, cystopteris, dryopteris and osmundas at Sizergh Castle, Kendal, Cumbria LA8 8AE (01539 69813, nationaltrust.org.uk); athyrium at 2 The Dell, Haywards Heath, Sussex RH16 1JG (01444 415271), open by appointment only; dicksonias (tree ferns) at Glasgow Botanic Garden, Glasgow G12 0UE (0141 276 1614, glasgow.gov.uk); dryopteris and polypodium at Harlow Carr Botanic Gardens, Crag Lane, Harrogate, North Yorkshire HG3 1QB (01423 565418, rhs.org.uk/harlowcarr); polystichum at Greencombe, Porlock, Somerset TA24 8NU (01643 862363, greencombe.org.uk) and The Lakeland Horticultural Society's garden at Holehird, Ullswater Rd, Windermere, Cumbria LA23 1NP (01539 446008, holehirdgardens.org.uk). Join the British Pteridological Society c/o Dr Alison Evans, Springfield House, Salterforth Rd, Earby, Lancs BB18 6NE, nhm.ac.uk/hosted_sites/bps; membership (£25) includes twice-yearly issues of the 'Fern Gazette'. Read 'Fern Fever' by Sarah Whittingham (Frances Lincoln £35)