Fern Britain: Anna Pavord has frond memories of a garden favourite

Giant fronds, instant shading, exotic shapes ... no wonder the fern is a popular plant. But why is the home-grown variety still such a rarity?

The way people go on, you'd think that only one fern had ever been invented – the New Zealand tree fern. Yes, it's a handsome thing and just right for West Country coastal gardens where it can rear out of jungly rhododendrons and vast magnolias and give a fair impression of elsewhereness. Sometimes it works in town gardens too. Much depends on the skill of the planter. It's one of the top three plants likely to be chosen for the kind of in-your-face exotic urban space that goes with lots of glass and metal. The other two, of course, are the banana and the phormium or New Zealand flax.

The problem is that the kind of tree fern urban trendies want is likely to be very expensive. They are priced by the amount of bare trunk under the fronds – the taller the trunk (which isn't actually a proper trunk at all) the more expensive the fern. There are practical advantages in having a tall one. You can plant underneath it, or place it at the edge of a deck so the fronds sway over your breakfast table. A tall tree fern provides shade and makes use of airspace that is perhaps less cluttered than space on the ground.

But the temptation, if you've paid a couple of hundred pounds for a plant, is to put it in a very prominent position, so you get the most out of what you've paid for. Ferns actually work best when they are not in the limelight. They are stars of course, but subtle ones. They draw you in quietly, work on you modestly. A tree fern is fantastic when you come upon it unexpectedly, not so good on its own in glaring light where it looks as though it has been accidentally dropped by a passing auk.

They are expensive because the trunks, or non-trunks, take a long time to develop. They are built up gradually from the stems of the fronds. Each spring, gardeners cut off the old, battered leaves, but the base of the stem remains and gradually these fuse together into a hairy column from which the new fronds draw their sustenance. These ferns don't have roots like other ferns, which is why it has been so easy for importers to fly them in from the other side of the world.

Ecologically, of course, it's better to buy home-grown ferns, but some nurserymen with expensive goods to sell will tell you that British-grown tree ferns never develop trunks. That's not true. It just takes time. The first tree fern I ever had came from a garden in Cornwall, where they self-seeded all over the place. The gardener whipped a seedling out of a dry-stone wall, I potted it up at home and now it has a trunk nearly two feet tall (and is still in a pot, though not the same one as it started in).

The way the trunk is built up dictates the way it needs to be looked after. The fern doesn't pull moisture up from the ground as efficiently as a plant with roots does. You need to keep the central column moist and I do this by emptying a can of water over the fern's head from time to time. The ribs of the fronds collect water and channel it down to the centre, where the dark brown hairs on the old dead stems absorb it like moss. But if you've got a very tall tree fern and can't reach its head easily, then hosing the trunk down from time to time will allow it to absorb the moisture it needs to develop its vast and beautiful leaves.

Last autumn I acquired two more tree ferns, British-grown, at the modest price of £4.50 each. They are planted in ivy behind a holly hedge, under the canopy of an oak, both of which I hope will protect them from frost. But I put them there too because the path that passes that way is at a much higher level. Looking down into the crown of a big fern is one of May's great pleasures and this month the ferns have been fantastic, flipping themselves open in a series of acrobatic moves more beautiful than any Olympic gymnast could devise.

For a gardener, ferns are not demanding creatures. You need to think a bit about suiting plant to place (frothy adiantums will cope with dry berths, osmundas won't) but after that there's only one thing you need to do and even that is for your benefit rather than the plant's. You must cut off the old fern fronds before the new ones start to uncurl. It's almost too late to do it now (how maddening it is to be told that – sorry) but you can always do it next year. The particular way ferns unfold themselves, slowly building a fountain of foliage, is far more beautiful to watch if your eye is not distracted by the weather-beaten fronds of the previous year. This is particularly true of dryopteris, the male fern, a British native that occasionally goes mad and produces fronds with crazy bunches at the end, or with double the amount of leaflets.

I'm not quite sure how it happened, but I seem to have nine different kinds of dryopteris in the garden, none more dramatic now than Dryopteris wallichiana, a native of Hawaii, Mexico, Jamaica and other places that might make you wonder whether it would survive a British winter. But miraculously, it does.

I'm so mad about it, there are now three big groups of it in the garden, one in a wild bit, where it grows with leucojum and ivy, another lot planted under the big arching branches of Rubus tridel 'Benenden', which has been flowering since the middle of the month, and a third group strutting its stuff with thalictrum and the tall, sword-leaved Iris orientalis, an iris that actually prefers damp soil. The midribs are as hairy as a monkey's arm and at this early stage, the fronds are an almost luminous yellow-green. Full grown, they can be four feet long.

Some groups are more shaded than others and each catches the light in a different way. This is important with ferns. Some will do in bright light, but the mystery of dappled shade gives them much greater allure. And if you have the chance to plant some of your ferns (particularly the vase-shaped ones such as Matteuccia struthiopteris) so you see them against the light, the drama increases considerably.

They are good mixers: Solomon's seal, primroses, snowdrops, irises such as I. orientalis or 'Gerald Derby', arums of all kinds, arisaemas, cyclamen, Euphorbia robbiae, hostas (but not too beefy), lily-of-the valley and smyrnium all look good with ferns. Having done a quick count, I find I've planted 25 different sorts and that's not counting all the native ferns that were here before we arrived. Somehow I feel it's not going to stop there. They've drawn me into their net.

For the best possible information on ferns read 'The Plantfinder's Guide to Garden Ferns' by Martin Rickard (David & Charles £19.99). Martin Rickard has sold his famous fern nursery but his plants live on with Ben Kettle at the World of Ferns nursery, Carreg y Fedwen, Lon Rallt, Pentir, Bangor, Gwynedd LL57 4RP, 01248 600385, world-of-ferns.co.uk. The nursery is open by appointment only. Send 5 x 1st class stamps for a catalogue.