GQT

Christine Walkden

Garden writer Christine appears on BBC1’s The One Show . She is also a lecturer and tour leader.

Anne Swithinbank

A keen fruit, vegetable and houseplant grower, Anne was formerly the glasshouse supervisor at RHS Garden Wisley.

Matthew Wilson

Garden designer Matthew was curator of RHS Hyde Hall and Harlow Carr, and often appears on television. Q Can I put woodchip boiler ash on our veg plot?

Terry, by email

A ANNE SAYS Ash contains phosphorus, potassium and micronutrients and, as long as it’s only from untreated wood, is safe to add to soil. It is alkaline, so it would be best to carry out a pH test of the soil to establish a starting point. Many veg like a slightly alkaline soil of pH6-7. With brassicas, a pH of just above 7 will help to ward off clubroot disease. Most fruit will benefit from the potash, but don’t give ash to crops that prefer slightly acidic conditions, like potatoes and raspberries.

Quantity is an inexact science, but try up to a couple of thin layers each winter, applied on a still day and forked in immediately. You can add thin layers to the compost heap, too.

When should I cut