1. Mark two circles around a tree one at least 75cm from the tree and another 50 to 60cm outside this one.
2. Drive wooden stakes 25cm into the ground at 30cm intervals around both circles. Weave hazel rods between the stakes (soak them if stiff), securing with nails.
3. Line the inside with plastic membrane. Fill with a 10cm layer of gravel followed by top soil, and compact down until level with the top.
4. Leave for a few weeks, gently compacting the soil. Finally, cut and lay turf on top.
Written by: specialist garden photographer Nicola Stocken Tomkins. Visit Nicola's website at www.gardenpix.co.uk.