Heavy Glossop clay and all

Designing for the soil you've actually got, not the one in the catalogue.

When the Sandringham show garden came home to the Gamesley community garden this summer, I had a problem. A lot of its plants, like Perovskia, Echinacea and Agapanthus, want full sun and sharp drainage. Gamesley has heavy clay and poor drainage. If you garden in Glossop, you'll know exactly what that means.

You put a spade in, and it either won't go in or won't come out. In winter the soil is cold porridge. By August it's set like a terracotta pot.

So we cheated a bit. Each plant went in on a mound, with a layer of gritty soil just around the root ball so it wasn't sitting in water. Then we mulched heavily with the sand and gravel left over from the show garden. So far so good. Winter is the real test, so we'll see who makes it through to spring.

But that was a rescue job for plants that were never meant to live here. Most of the time, the answer to clay isn't to fight it. Heavy clay has a bad reputation, and it's partly earned. I've come round to it, though. It's one of the most fertile soils you can have.

What's actually going on down there

Clay is made of very fine particles that pack tightly together. That's why water sits on top in winter and why it cracks in a dry spell. It's also why clay holds on to nutrients so well. Plants that can get their roots into it are often bigger and healthier than the same plants on sandy soil.

The problems are mostly about water and air. Roots need both, and waterlogged clay squeezes the air out.

Right plant, right place

The best thing you can do on clay is choose plants that like it. That sounds obvious, but a lot of garden heartbreak comes from falling for a plant that wants a Mediterranean hillside and putting it in a Derbyshire bog.

Plenty of good things are happy on heavy soil. Roses, hardy geraniums, Persicaria, asters (Symphyotrichum), daylilies (Hemerocallis), Astrantia, dogwoods (Cornus), Viburnum and crab apples (Malus) all do well.

A few things that genuinely help

• Organic matter. Always. If you remember one thing, make it this. Compost, leaf mould or well-rotted manure, spread on top every year, is the answer to nearly every clay problem. Over time it opens the soil up, helps it drain in winter and hold water in summer, and feeds everything living in it. The worms do the digging for you.

• Avoid amendments where you can. It's tempting to try to turn clay into a different soil by digging in sand or grit across a whole bed. It's a lot of work, it rarely does what you hoped, and sand can make it worse. Choose plants that suit the soil instead. The grit at Gamesley was a targeted fix around individual root balls, not a way of changing the soil.

• Plant in autumn. The soil is still warm from summer and it's reliably moist, so roots can grow out and settle in over the winter. By the time the soil bakes hard the following summer, the plant has a proper root system and can look after itself. Plant the same thing in May and you'll be watering it all summer.

• Stay off it when it's wet. Walking on wet clay, or digging it, squashes out what little air there is. Lay a plank down if you must.

• Plant a little high. On a slight mound, so the crown of the plant isn't sitting in a puddle all winter. Just be careful to mulch appropriately around the crown to protect it from frosts!

  
  

Designing for what you've got

This is really what I mean when I say I design for the place. A garden that fights its soil is a garden you'll be fighting forever. One that works with it gets easier every year, and it looks like it belongs.

So yes, heavy Glossop clay and all. If you're wrestling with yours, fancy a brew? I'm happy to talk soil.