Environment minister Hilary Benn announced the new target, a consumer awareness campaign, under the "Act on CO2" banner, to promote buying peat-free growing media and a summer consultation for growers on peat use.
Benn said labelling could be better but that good alternatives are now available. On the trade side, he said: "We recognise this is tough because we're facing competition from plants grown overseas."
But garden centres, which Defra has asked to run a peat-free promotion featuring Diarmuid Gavin, were not happy with the target.
Glendoick Gardens & Garden Centre director Ken Cox said: "I will set up a peat shrine in my garden centre with evidence against not using it and to say the Government is talking rubbish. This is not an issue in the rest of the world. When will the British Government admit it is wrong?"
Squires Garden Centres managing director Dennis Espley said: "If this is going to be legislation we will comply with it. "
Hillier managing director Andy McIndoe added: "I am all for reduction in use of peat providing the full environmental impact of the alternatives is always considered."
But the RSPB conservation director Dr Mark Avery complained: "The Defra scheme would not affect commercial growers, who account for a third of the UK peat use."
Defra has given up on the old "crude" 2010 target of 90% peat reduction across the board and is placing the burden for reduction on garden centre customers.
The organisation will release a consultation document in the summer to examine reduction in professional use of peat. Consultant Susie Holmes said it should consider peat use by professional growers sectors because some sectors can achieve higher levels of reduction than others.
She added that data was out of date, with latest 2007 figures showing 72% peat use by amateur gardeners and 81% by professionals.
- Diarmuid Gavin appears in a campaign video demonstrating peat-free in garden centres. In 2006 he backed Westland's 80% peat multipurpose compost.
Defra said Gavin advertised Westland only after persuading the company to develop the reduced peat West+. A Westland representative said it started work on the West+ programme in 2000. It launched in 2005.