Q What are the alternatives to vermiculite and perlite?
Christine Lewsey, Essex
A MATT SAYS Both vermiculite and perlite are natural products obtained by mining, but little is made of the fact because few gardeners are aware of this or question its origins. Perlite is moderate at retaining water and nutrients and, when used in larger volumes in compost, acts as insulation for plant roots and improves drainage, especially for plants such as cacti.
Vermiculite is spongy and excellent for absorbing water and holding on to nutrients, so is often used in or for top dressing when seed sowing or mixed into compost to improve water retention for stronger, healthier growth.
You can use sharp sand or horticultural grit to improve drainage, though both are also extracted from the ground.
You can avoid or reduce use of these products with peat-free composts (see page 63), which are open, but be careful with watering and feed plants more often.
Feed your lawn in spring and autumn to improve vigour