But shortages of some products such as watering cans and greenhouses are worrying retailers.
Shoots Garden Centres director Piers Mummery said: "We had a stonker. What a superb start to the season. Our sales were more than double last year's. Grow-your-own is 300 per cent up on last year."
He added that a children's weekend organised to celebrate five years of the site at Washington, West Sussex, had increased footfall by 50 per cent.
Mummery said he had run out of some products, adding: "It's hard for suppliers if retailers are not booking pre-season."
He said: "We have moved away from pre-season orders to a little-and-often policy. But we need to be more forward-thinking now.
"Because sales this year compared with last year are worlds apart, a lot of people have been caught out. The person with more stock will be king if the good weather continues."
Mummery said the season had been the best for Shoots since opening in 2004 after a "torrid" six months last year.
Leading supplier Solus said one line of watering cans and four-tiered greenhouses had run out for half a day last week but both were now back in stock.
Brand manager Martin Ward said: "It's systematic of the whole credit situation that a lot of centres have not made larger pre-season orders. They may have been carrying stock from previous months, but now trade is picking up and they are clamouring for stock again."
Garden writer Peter Seabrook said: "Garden centres are bucking the trend and takings have soared two weeks earlier than normal."
- Wyevale sales are up by 46 per cent for the second week of March and by 69 per cent last week.
- Dobbies sales for the third week in March are up by 73 per cent.
- Thompson & Morgan said that 17 of its early potato varieties had sold out.
- Suttons marketing manager Tom Sharples said: "A boom in strawberry growing is inevitable."
- Spring bedding plants could sell out before summer bedding is ready to be rolled out, said retailers.
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GROWTH OF TOP-UP ORDERING INCREASES SUPPLY CHALLENGES
Solus had a record day for orders on 23 March as garden centres "panic ordered" after the best March weekend for five years.
Solus supplies to 2,000 gardening outlets, and managing director Nick Davies said this showed that retailers were no longer making big pre-season orders but had now fully moved to a top-up system.
He explained: "Monday's order intake was a record high. That shouldn't come as a shock to any supplier. Most have seen ordering patterns from retailers changing to a little-and-often approach with a greater concentration in March, April and May.
"Multiples are doing the same. You have to have the capacity of warehousing and vehicles to manage that - this year it is more apparent than ever before.
"If the wonderful weather continues it's going to challenge a lot of people because I believe there is pent-up demand for consumers to spend money on the garden."
Davies said this March is "exceptionally" better than last March, which had Easter in it, and retailers are achieving levels above those of March 2007.
He added: "The marketplace is not carrying the depth of stock it has done in previous years because it has been caught out in the past with vast stocks. There will be a number of sectors hit very hard this year - no question."
Davies said some grow-your-own products, such as raised beds, are selling at rates 100 times greater than in the past.
"Demand had far outstripped anyone's expectations because the consumer has gone out and purchased veg seeds and raised beds and four-tier greenhouses.
"If you're a supplier in that marketplace you will have done your forecasting months ago. As a business you have to anticipate how big that's going to be."