Water sitting on clay? Test a crumb before you buy.
Gypsum fixes one cause of puddling: clay that falls apart in water and seals the surface. A crumb of soil in a glass of rainwater tells you overnight if that is yours. If so, Liquid Gypsum goes on with a watering can. No digging.
£19.99 1 litre
Choose Liquid Gypsum★★★★★ Shop rated 4.95/5 from 513 reviews. Free UK delivery over £40. Dispatched in 1 to 2 working days.
- Works on clay that falls apart in water. On clay that holds together, the effect is modest.
- Calcium and sulphur with no change to pH. Lime raises pH; most clay gardens do not need that.
- Does not fix packed soil or poor drainage. The clay lawns page shows how to tell them apart.
The one-day glass test
- Take a dry, pea-sized crumb from 5 to 10 cm down. Do not crush it.
- Drop it into a glass of rainwater. Do not stir.
- Look after ten minutes and again next morning.
| What you see | What it means | Will gypsum help? |
|---|---|---|
| Cloudy water | Clay that falls apart in water and seals after rain. | Yes |
| Crumb slumps, water clear | Softens but holds together. | A little. Compost does more. |
| Crumb intact, water clear | Holds together. The problem is deeper. | No. Check drainage first. |
Lime or gypsum?
| Liquid Gypsum | Garden lime | |
|---|---|---|
| Calcium | 19.55% | Yes |
| Soil pH | No change | Raises it |
| Sulphur | 15.31% | None |
| Clay that falls apart | Holds it together | Little effect |
| Choose when | pH near neutral, or the glass clouds | pH below about 6 |
How much, how often
| Job | Mix | When |
|---|---|---|
| Clay programme | 15 ml per litre, 1 litre per m² | Fortnightly for three months from early autumn, then about every three years |
| Lawn feed | 10 ml per litre, 1 litre per m² | Autumn or spring |
| Beds and borders | 5 ml per litre | Autumn or spring; feed rate only May to August |
Shake 30 seconds; mix fresh. Not on frozen or waterlogged ground. Cost for your area: price page or calculator. Not the real thing? See gypsum vs calcium thiosulfate.
Common questions
How long before I see a change?
Water soaking in rather than sitting can show within the first few rains. The deeper change takes a season or more. Nothing after a full programme means the problem is deeper down.
Can I use it on a lawn without lifting the turf?
Yes. That is why it is a liquid. Spike the lawn first if a screwdriver will not go in.
Is it safe around pets and children?
Treat it as any garden concentrate: off while you apply, back on once it has soaked in. More on the pets and children page.
If your clay clouds the water, this is the tool
15 ml per litre, a litre per m², fortnightly for three months from early autumn. Watered on, not dug in.
£19.99 1 litre · 5 litres £72.99
Free UK delivery over £40. Dispatched in 1 to 2 working days. Packed and sent from Stockport.