Why wind, not cold, is the real challenge

Most British ferns will shrug off a hard frost without complaint. What they dislike is being dried out and battered at the same time. On a balcony or an exposed patio, wind strips moisture from the fronds faster than the roots can replace it, and a steady buffeting frays the tips until they crisp to brown. Add the rain shadow cast by a wall or an overhanging eave and you have a plant sitting in bone-dry compost in the one spot it cannot escape from.

None of this means ferns are off the menu for a windy site. It simply means choosing tough species and getting three things right: the pot, the water and the shelter. Get those sorted and a container of ferns can look better than anything else you could grow out there.

Ferns that shrug off a buffeting

Start with the natives, because they evolved here and know what a British gale feels like. The following all perform well in pots on exposed sites:

• Common polypody (Polypodium vulgare) — grows on walls and tree branches in the wild, so leathery fronds and dry spells are second nature. Ideal for a shallow pot or a wall-mounted planter.
• Hart's tongue fern (Asplenium scolopendrium) — evergreen, with glossy strap-like fronds. It hates drying at the root, so give it a generous pot, but it handles wind well once established.
• Hard fern (Blechnum spicant) — neat, ladder-like evergreen fronds and a compact habit. Happiest in humus-rich, slightly acid compost and surprisingly tolerant of exposure.
• Golden-scaled male fern (Dryopteris affinis) — a better bet than the common male fern for a windy patio, holding its fronds well into winter and forgiving occasional drought.
• Soft shield fern (Polystichum setiferum) — an elegant evergreen shuttlecock. Tough, but its fronds are soft, so keep it out of the very fiercest wind.

Leave lady fern and royal fern for a sheltered, damp corner. They are beautiful plants, but they want still air and consistent moisture, which is precisely what an exposed patio cannot offer.

Pots, compost and a bit of ballast

Size matters more than style. A larger pot holds a bigger reservoir of moisture and is far less likely to take off across the patio in a gust. Go for frost-proof terracotta or glazed stoneware; plastic is light, which makes it easy to move but easy to topple. Whatever you choose, stand pots on feet so water drains freely and air circulates underneath.

For compost, a loam-based peat-free mix is the best starting point — it has weight, holds moisture and does not blow away. Fork through plenty of leafmould for the humus ferns crave, plus a good handful of horticultural grit for drainage. Then top-dress the surface with a centimetre of grit. This keeps the crown of the plant dry, discourages liverwort and stops the wind lifting bare compost out of the pot on a blustery day.

Positioning is part of the engineering. Group pots together so they shelter one another, put the heaviest containers on the windward edge, and keep tall ferns away from balcony railings where a gust can catch the fronds like a sail.

Watering: little and often will not do

This is where most container ferns are lost. A quick splash from the can wets the surface and nothing else, leaving the rootball dry an inch down. Water thoroughly, in the morning, until it runs out of the drainage holes — and check daily through the growing season, twice a day during a hot, windy spell. Morning watering lets the fronds dry before night, which reduces the risk of rot.

Rainwater from a butt is ideal, though most ferns cope perfectly well with tap water. A tray of damp gravel beneath the pots raises humidity around the fronds and takes the edge off a drying wind. Mulching the surface with leafmould in spring slows evaporation, and in winter, evergreens in a rain shadow still need the occasional drink — dry cold is harder on them than wet cold.

Shelter without creating a wind tunnel

A solid barrier seems like the obvious answer, but it creates turbulence and downdraughts that can be worse than the wind itself. Instead, use a permeable screen — slatted fencing, trellis or a woven hurdle — that filters roughly half the airflow. Even a row of pots with low-growing plants around their feet will break the wind at frond level.

If you garden near the coast, salt is an added problem. After a severe gale, rinse the fronds with a can of fresh water to wash the salt off before it scorches the leaves.

Keeping them going year after year

Repot in spring, in March or April, just as the new croziers begin to unfurl, and divide congested crowns at the same time. Feed lightly from April to July with a diluted seaweed or general-purpose liquid feed — ferns are not hungry plants, and too much nitrogen produces soft, wind-damaged fronds.

In late winter, cut deciduous ferns back to the base and tidy evergreens by removing only damaged or dead fronds. Never cut the fronds of hart's tongue fern, as new ones emerge from the crown rather than replacing the old.

Before the worst of the winter, move pots to a sheltered corner against a wall, check they are sitting on feet, and wrap the pot — not the crown — in bubble wrap or hessian. Keep an eye out for vine weevil grubs in containers, which can hollow out a rootball quietly over winter. Do all that, and a windy patio becomes one of the best places in the garden for ferns: the moving air keeps their crowns healthy, and the sound of fronds rustling in a gust is worth the extra watering alone.