Figures released by the Garden Centre Association (GCA) showed the first quarter was 12% up, with plants 35% up.
Early returns from 14 centres showed a seven per cent increase in sales in March 2011 compared with March the year before.
Last weekend, sales at some centres were 25% up on last year, despite the dates corresponding to Easter weekend in 2010.
The areas selling best were plants and core gardening, as gardeners replaced plants lost to the winter freeze. However, grow your own has yet to take off.
Sales were helped by the driest March for 53 years and 25% above average sunshine in the same month.
Essex-based Alton Garden Centre owner Andy Bunker said: "Our plant, compost and pot area outside accounts for 22 or 23% of total turnover. I have just recorded my best ever March and my best ever start for the first three months. Long live core gardening."
Blue Diamond managing director Alan Roper said: "Trade has gone ballistic due to the seasonable gardening weather combined with a late Mother's Day."
Coolings managing director Gary Carvosso added: "We had our best weekend ever in both our cafes and our plant-orientated site was 102% up on the same weekend last year."
Armitage's Garden Centres director Will Armitage said: "We're up by double figures. The new cafe at our Pennine garden centre has pulled everything else up."
But there are clouds on the horizon, with some garden centres not stocking up ahead of the four bank holidays between 22 April and 2 May.
Garden Industry Manufacturers' Association director Neil Gow said: "It's a mixed bag from retailers, but on the whole it's positive. Plants and core gardening are the areas that are particularly strong."
But he warned that some retailers had not bought ahead because of cash flow problems and could be short-stocked come Easter - a problem compounded by the fact that banks were not lending, a poor December and the traditionally quiet January and February.
Supplier Bayer Garden marketing director Steve Mead said sales had been slow and garden centres must order now to meet expected demand.
Gillie Westwood, chief executive, GCA
"We've had a good start to the year weather-wise, but now I'm worried about hosepipe bans. There's going to be a lot of just-in-time ordering. If we have good weather over the bank holidays there could be shortages."
Martin Stewart, owner, Stewart's Gardenlands
"We're 17-18 per cent up. Because Easter and Mother's Day are later this year, there's a shift from houseplants to outdoor plants. There is no doubt people want to garden. "
Andy Bunker, director, Alton garden Centre
"We have been through recession, high interest rates, unemployment and fuel hikes, but if the sun shines we make money. Trade was excellent for Mother's Day. We smashed last year by almost 25 per cent."
GCA sales figures First quarter 2011
Section March January-
2011 March 2011
Outdoor plants U 28% U 35%
Garden sundries U 13% U 12.5%
Furniture and bbqs U 7% U 10%
Hard landscaping U 9% U 15%
Catering U 3.5% U 12.5%
Seeds and bulbs U 2.5% U 9%
Pets and aquatics D 1.5% U 3%
Houseplants D 35% D 15%
Gifts D 14% U 2%
Overall U 7% U 12%