Why Two Layers Beat One

A single wool throw feels wonderful for about twenty minutes. Then the damp starts creeping up through the seat, the wind finds the gap at your back, and you're heading indoors just as the light turns that lovely amber colour. The problem isn't the wool — it's that wool on its own has nothing to stop moisture and cold air pushing up from below.

The fix is simple and satisfying: pair a proper wool throw with a waterproof backing layer. The wool traps warm air around you, while the waterproof layer blocks the chill and damp rising from the chair, the ground and any passing shower. Between them sits a pocket of dry, still air — which is what actually keeps you warm. Make it as one detachable blanket and you'll get another hour or two of reading out of every clear evening, right through into October.

Start With the Right Wool Throw

Wool is the right choice because it insulates even when it picks up a little atmospheric damp, and it doesn't hold onto odours the way synthetics can. When you're choosing one for garden use, look for:

• Size: at least 130 x 170cm. Bigger is better — you want it to wrap around your shoulders and still cover your knees when you're curled up.
• Weight: roughly 500–700gsm. Anything lighter will feel flimsy in a breeze; anything heavier becomes a nuisance to carry out.
• Weave: a tight twill, herringbone or whipcord. Loosely woven blankets snag on chair arms and let the wind straight through.
• Fibre: lambswool or merino for softness against the neck, Shetland or a recycled wool blend for hard-wearing garden duty.

If you already have a favourite throw, use it. There's no need to buy new — this is a project about making what you own work harder.

Choosing a Waterproof Backing

This is the layer that does the quiet, unglamorous work. You want something flexible, genuinely waterproof and — crucially — not noisy. Crinkly plastic sheeting will rustle every time you shift in your chair, which ruins the whole point of a peaceful read.

Good options include PU-coated ripstop nylon, waxed cotton, oilcloth, or the backing from a lightweight picnic blanket that has seen better days. Waxed cotton is the most sympathetic to the wool visually, though it needs occasional re-waxing. Coated nylon is lighter and packs down smaller if you want to leave the blanket out in a basket.

Cut or choose the backing slightly smaller than the throw — around 10cm narrower on each side works well. That way the wool drapes over the edges, the blanket still looks like a blanket, and the waterproof layer stays tucked underneath where nobody sees it.

Joining the Two Layers

You have three sensible approaches, and the first is the one I'd recommend.

• Detachable press studs. Fit metal poppers at each corner and at 30cm intervals along the long edges. The layers stay together in use, but the wool lifts off for washing. This is by far the most practical option.
• Ribbon ties. Sew short lengths of cotton ribbon to both layers and knot them together in bows. Softer, prettier, slightly fiddlier in the dark.
• Stitched permanently. Run a seam around the perimeter with a heavy-duty needle and strong thread. Quick, but it means hand-washing the whole thing from then on.

No sewing machine? Adhesive hook-and-loop tape applied to both layers works perfectly well, and it lets you separate them whenever you like. Simply folding the two together and storing them as a pair is also a legitimate strategy — just tuck the waterproof layer under the wool each time you settle in.

Finishing Touches That Make a Difference

Once the basic blanket works, a few small additions turn it into proper outdoor furniture. Consider adding:

• Corner pockets for a paperback, reading glasses and a small torch, so nothing has to balance on the arm of the chair.
• A webbing strap across the middle of the backing, which slots over the chair back and stops the whole thing sliding down.
• Small weights — curtain weights or bean bags — stitched into the hem of the waterproof layer to hold it steady in a gust.

Pair the blanket with fingerless gloves, a vacuum flask of something hot and a clip-on reading light, and you have a genuine outdoor reading station rather than a hopeful chair with a rug on it.

Keeping It Fresh for the Season

Garden blankets pick up pollen, leaf litter and the odd splash of tea, so give them a shake and an airing after each use rather than leaving them folded damp on the seat.

Wool should be washed by hand in cool water with a wool-safe detergent, then dried flat and away from direct heat. The waterproof layer just needs a wipe with a damp cloth and a proper dry before storage. Store the two layers rolled together in a cotton bag with a cedar block, not in plastic — plastic traps any lingering damp and encourages that fusty smell that no amount of lavender will shift.

Look after it properly and this blanket will see you through years of September evenings, when the garden is at its best and the house feels like a shame to go back into.