“It rained a lot last night” is usually wrong — why British gardeners are quietly losing plants to guesswork, and the simple glass gauge that ends it
Mervyn Tolley, a glassblower from Stourbridge, with two of his hand-blown rain gauges. Each tube is blown, cooled overnight and marked by hand.
8-min read by Gillian Thewlis
31 October 2026
Summary: Most garden plants that fail are not lost to pests or bad luck, but to watering that does not match the weather — too much after a wet week, too little after a dry one. The fix is surprisingly old-fashioned: measure the rain that actually falls on your own garden . A Stourbridge glassblower makes a hand-blown gauge that does exactly that, survives British winters and reads at a glance. He works alone, so they come in small batches: the current one is 96 gauges, and the next will not be ready before spring.
Ask ten gardeners how much rain fell last night and you will get ten confident answers. Ask them to prove it and almost nobody can. We judge rain by the sound on the window, by how dark the patio looks in the morning, or by the number on a phone app.
None of those tell you what your soil actually received. A loud shower can deliver barely 3 mm. A soft, steady drizzle can deliver 15 mm without anyone noticing. And the plants in your borders respond to the millimetres, not to the noise.
That gap between what we think fell and what really fell is where a lot of garden losses begin.
The quiet problem in British borders
Most established garden plants are comfortable with roughly 25 mm of water a week, from rain and watering combined. Get far below that in a dry spell and shallow roots suffer first: wilting at midday, flowers dropping early, vegetables bolting. Go far above it and the problem flips — waterlogged soil pushes out the air roots need, and plants start to fail from below while the leaves still look fine.
One measuring tube, still orange on the pipe. Blown glass stays clear for years, where moulded plastic yellows in the sun.
“A garden won’t tell you what it needs. It just quietly gets too much water or too little, and by the time you can see it, you’ve already lost something. All this does is take the guessing out of the morning.”
Mervyn Tolley, 69, spent forty years blowing glass in the crystal works along the Stourbridge canal before setting up his own small bench at home. He started making rain gauges for a simple reason: he kept losing his own plastic ones to the frost, and he wanted one that would still be readable in ten years.
At 69 his hands are slowly starting to let him down. One tube now takes him most of a morning, and there is nobody lined up to take the bench over. When a batch is gone, it takes him months to make the next.
“I waited forty years to make something that was mine. I’d like to keep doing it as long as my hands let me.”
Why so many rain gauges don’t last
“Most of them aren’t built to last a winter,” Mervyn says. “They’re built to be cheap.”
If you have owned one, you will probably recognise at least one of these.
Five Ways a Rain Gauge Gives Up
1. It cracks the first time the water freezes
Water left in a tube expands as it freezes. Thin plastic splits, often right at the bottom, and you find it in spring with a crack you cannot repair.
2. The plastic yellows and clouds over
Sunlight does to a moulded tube what it does to an old car headlight: yellow, then milky, until the water level is hard to see at all.
3. The markings wear off
Printed scales fade with sun and rain. Once the numbers go, you are holding a clear tube that measures nothing.
4. The stake bends, or sits too low to read anything true
A gauge close to the ground catches splash off the soil and the patio, and a leaning one collects more or less than actually fell.
5. And when it breaks, there is no replacement tube
The glass or plastic goes, and the model is no longer sold. A frame with nothing in it is just garden decoration.
What a better gauge looks like
The dragonfly goes on last. Its blues and greens are temper colours from the heat, not paint.
“First winter, I lost two plastic ones,” Mervyn says. “Split right at the bottom. That’s when I started thinking about it properly instead of just making a pretty thing.”
The tube lifts out — and that alone solves the freeze
The glass sits in an open forged ring, not a closed sleeve. One hand lifts it out when frost is forecast and drops it back in come spring. No tools, no bracket to unscrew with cold fingers.
Blown, then cooled slowly overnight
Slow cooling (annealing) lets the stress out of the glass wall, which makes it far tougher than glass that is cooled quickly. Clear glass also does not yellow in the sun.
Both scales, marked onto every single tube
Millimetres down one side, inches down the other — read it whichever way you think. Because each blown tube is slightly different, Mervyn calibrates every one with a measuring cylinder before marking it.
Forged iron, not stamped tin
The stake goes in with a push of the heel and stays upright, so the gauge sits at a sensible height away from splash and reads true.
A songbird and a dragonfly, coloured in the fire
Worked metal, not stickers. Handmade, so no two are exactly alike — something nice to look at even on the days you are not measuring.
A thermometer out where the plants are
The dial is checked against a reference thermometer before it leaves the bench. Celsius and Fahrenheit on the same face, readable from the path, nothing to charge or replace.
The most useful thing a rain gauge does is boringly simple: it turns watering from a habit into a decision. Instead of watering on Tuesday because it is Tuesday, you look at the tube.
Ten seconds with a cup of tea: read the tube, empty it, decide whether the garden needs anything today.
After a wet week you leave the hose coiled and let the roots breathe. After a dry, windy week you know the borders are behind, even if the sky looked grey. And in a hosepipe-ban summer, you stop spending precious water on beds that already had enough.
It also changes how you read the forecast. Over a few months you learn how much a “showery day” really brings to your particular corner of the county — which is often quite different from the town three miles away.
Four things that change the morning after you put one in
💧
You stop guessing whether to water
Around 25 mm a week is a good rule of thumb for most established borders and vegetables, and the millimetre scale runs right up the tube. One glance tells you whether to drag the hose out or leave it alone.
🌱
You stop drowning the plants you care most about
Roots in waterlogged soil cannot take up oxygen, and the plant fails from below while looking fine on top. Knowing what fell means you only add water when it is genuinely needed.
🌡️
It warns you before a frost takes the tender plants
The dial reads the air out where the plants are, not on the sheltered house wall. In spring and autumn that difference can decide whether the dahlias come in tonight or tomorrow.
🚶
It gives you a reason to walk out there every morning
You go out to read the tube and notice the greenfly, the bud that opened overnight, the robin at the feeder. Ninety seconds that put you back in your own garden.
In the border by the front gate, close enough to read on the way past without stopping.
“I’d sooner they went to people who’ll put them in the ground and use them,” Mervyn says, “than sat on a shelf looking pretty.”
Why not just use the weather app? Because the rainfall figure on your phone is usually an estimate from radar, spread across a grid that covers many streets at once. Everyone who gardens has watched a shower soak the next road and miss their own.
The only rain that matters to your plants is the rain that lands on your soil. A gauge is the simplest way to measure exactly that.
None of this is dramatic, which is exactly why it is easy to ignore for years. But small, regular adjustments add up to healthier roots, fewer losses and less wasted water.
Before and after
Without one
You water on a schedule and hope it was right
“It rained quite a bit last night” — and it was barely 6 mm
The app reports rain for half the county
A cracked plastic tube every spring
Water wasted on beds that were already wet
With one
You water on evidence, only when it’s needed
You know overnight rainfall before your tea goes cold
You know what fell on your soil
The tube comes in for winter and goes back out
A forged songbird and dragonfly out there all year
Same allotment, same week: the bed on the left was watered out of habit, the one on the right only when the gauge said so.
I hoped the colours would look as good in real life as in the photos — they’re better. You can tell it’s handmade: the glass has weight, the metal feels thick and properly finished. A month out the front and it still makes me smile.
Peter H., Kidderminster
★★★★★
Ordered it half expecting a battle with instructions and a bag of screws. Instead the tube slid straight into the bracket and the stake went in with one push — five minutes, no tools. Two proper downpours since: no wobble, no fading.
John R., Leeds
★★★★★
I’ve stopped watering the tomatoes every evening out of habit. Some weeks the gauge says they’ve had plenty, and they’ve honestly never looked better. Nothing like the cheap plastic one I had before.
Brian K., Ludlow, Shropshire
Questions people ask before they order
Do I really have to bring it in for winter?
You bring in the glass tube, not the whole thing. The forged frame stays in the ground all year. When frost is forecast you lift the tube out with one hand and pop it on a shelf; in March it drops straight back in.
What if the glass breaks anyway?
Glass is glass, so replacement tubes are available. If yours breaks we send a new tube — free for two years from delivery.
Is it marked in millimetres or inches?
Both. Millimetres down one side of the tube, inches down the other. The dial carries Celsius and Fahrenheit the same way.
Where should I put it?
In the open, away from the house, trees and gutters, so it catches the rain that really falls on your beds. Read it at the same time each morning and tip it out afterwards.
The glass travels wrapped in its own sleeve, packed separately from the frame.
Made by hand: glass blown and slowly cooled, both scales marked onto each tube, frame and stake forged, songbird and dragonfly shaped and heat-coloured — by Mervyn in Wordsley, Stourbridge.
Site it in the open: away from the house, trees and gutters, with the dial in morning sun rather than full afternoon glare — any dial thermometer in direct summer sun reads warm.
Built to survive winter: the tube lifts out of its open ring in one motion before the first hard frost. No tools.
Glass, not plastic: does not yellow, cloud or warp in the sun.
Two readings, both scales: rainfall in millimetres and inches, temperature in Celsius and Fahrenheit — on one stake, out where the plants actually are. No batteries, no app.
Made in small batches: this batch is 96 pieces. When it is gone, the next one takes Mervyn several months at the furnace.
Update — this week
More than half of this batch has gone since the article went up. Mervyn is back at the furnace, but the next gauges won’t be ready before spring.
Gardener’s tip: Read the gauge at the same time every morning, note the number, and tip the tube out. Add up the week on Sunday: if your borders have had around 25 mm, leave the hose alone. If they have had much less, give them one deep soak rather than a little every evening — deep watering builds deeper, tougher roots.
