Q What’s a high nitrogen fertiliser?

Marie Mallison, Hull

A A readily available form of nitrogen for plants is ammonium sulphate from garden centres and DIY superstores. Liquid feeds based on nettles have a small amount, but only a fraction of that of ammonium sulphate. Dried blood would be the best option. Garden Direct (www. gardendirect.co.uk; tel: 0845 217 0788) supply mail order.

Use dried blood as a top dressing to give leafy plants a boost