This could lead to familiar varieties dying out as gardeners are forced to move on to newer seed types, experts have warned.
The UK's biggest seed suppliers, including Suttons Seeds, are packing 2010 seed for delivery this year to meet current orders.
Suttons marketing manager Tom Sharples said: "We're having to draw on next year's stocks to keep up with demand. Everything is going mad this year.
"It is quite possible stocks will run short of top-sellers such as runner bean Scarlet Emperor, so demand will be spread onto new varieties such as runner bean Celebration, for instance.
"We're always encouraging people to try new things so it has to be a good thing. Gardeners are very traditional and stick with what they know but newer varieties are often more disease resistant, so this is better if you want to be organic."
Vegetable seed sales have risen 25-30 per cent in the past few years, but repeat orders from garden centres are so high they will be up five to eight per cent on top of that this year.
Sharples said: "Five years ago, we sold 70 packets of flower seeds for every 30 packets of veg seeds, but that is now 70 veg for 30 flowers and will rise to 75/25 this year. There is more to come."
Suttons is involved in grow-your-own campaign We Will if You Will with the National Trust and B&Q.
Garden writer Peter Seabrook said: "There will be real shortages in 12 months because seed companies are running down next year's stocks. There is going to be a shortage of traditional popular brands.
"This could be a very good thing because if you sell out, gardeners will be pushed onto modern hybrids which are available in greater quantity for the commercial trade. The average gardener will see better results from modern varieties and this will kill off the old ones."
Kings Seeds purchasing manager Peter Miller said: "Seed harvests in 2007 were bad and in 2008 they were awful. Broad beans are short. There are hardly any about until the new crop in October or November."
But he said he had other crops available and that most customers preferred traditional choices.
Runner bean Scarlet Emperor
Parsnip Hollow Crown
Carrot Autumn King
Brussel sprout Evelyn Special
Runner bean Celebration
Tomato Sungold F1
Carrot Kingston F1
Brussel sprout Nelson