Drought is the word on everyone's lips in gardening circles and it means retailers are altering their offer. This season, Sainsbury copied Tesco in setting up marquees to sell gardening products. Supermarkets have found barbecues, garden furniture and play equipment lucrative impulse lines as Britain heats up.

Plant sales have been poor for three seasons because of dry weather and a decline in interest after the demise of TV's Ground Force. Rainfall in the south east has been down since November 2004 and several water companies have introduced hosepipe bans. This means gardeners are not buying plants.

Instead, supermarkets are selling drought-tolerant species such as lavender, as well as Mediterranean plants, including santolina and olive trees. Tesco is moving into fashionable 'instant garden' plants, particularly tree ferns and phormiums.

Industry body the Horticultural Trades Association found that consumers spent £161m in a £5bn market on garden products from supermarkets in 2005, up 2% in a market that fell by 10%. Since 2001, the supermarket gardening product mix has moved from 73% plants to 59%. Chemicals and fertilisers are up 148% and outdoor living up by a third - trends that seem likely to continue.

Looking ahead, Asda is trialling a touchscreen system to sell garden furniture in two stores and Tesco is looking at an Argos-style catalogue in-store that may feature gardening. The Asda Living concept will also move supermarkets more into gardening. Tesco and Asda are also featuring more own label staple gardening products, including tools. Niche areas include gardening for children - Tesco launched a range of tools for kids last month - and seeds, an area where there is fierce competition.

Supermarkets may be forced to move away from selling peat and some chemicals because of environmental concerns, while Tesco and Sainsbury have not gained planning permission for as many marquees as they hoped. However, they are sure to develop the concept. The advantages of being able to dip into a market where 35% margins are not uncommon are irresistible, particularly when putting up marquees is such a cheap way to add retail space.