Some people recommend gypsum, I haven't as digging in organic material year after year and while its hard work will show results eventually as have done it before. Use composted grass, carboard, newspapers, leaves, well rotted farmyard manure etc. Obviously you may not be able to do it all overt the garden if extensive but concentrate on limited areas like flower beds and borders.

I've even piled lawn mowings on empty parts and dug them in after they've been there all winter. Chop up autumn leaves with your lawn mower and do the same with those. After all nature mulches its plants with autumn leaves. If you worry about nitrogen depletion with the rotting you can always add some Growmore before you are ready for planting. If you have easy access to beaches you can collect seaweed and use that as a mulch too after rinsing the salt out. The worms will take some of all this down so digging should be a bit easier but just take it a bit at a time. As Taurman says it takes time but you will see an improvement from year to year. And some plants like clay - roses for one. If its acid clay a dressing of lime may help but test it first in case it isn't.

Thakks

Thanks very much

Agree with the others, as much organic well rotted material as you can possibly afford, as often as possible - but also, horticultural grit, which you can buy in bags from the garden centre (usually around 30/40 litre bags).

If the area's not already planted, then gypsum would be useful, but not recommended where planting is already present, or at least, you have to reduce so much the amount you can use, it's hardly worth putting it on and is therefore not so effective.

When we could rely on cold winters, turning the soil over and leaving it in clods in autumn meant the frost would break it down, but we don't get the cold we used to get any more, so its not as effective.