England and Wales received only 21mm of rain last month, a third of the long-term average, according to the Environment Agency.
The situation was particularly bad in East Anglia - where growers are already irrigating round the clock to give their crops the best chance of success.
Andrew Wortley, a potato and vegetable grower from OW Wortley & Sons in Thetford, Norfolk, said: "The situation is very serious. We are irrigating parsnips just to get them to germinate. Fortunately, we have four reservoirs, 14 irrigators and a lot of people running around. But the operation is costing us an extra £100 an acre."
Stephen Francis, managing director of Fen Peas producer organisation in Lincolnshire, agreed. "The weather is drier than we have ever had it at this time of year," he said.
"We are still drilling peas into moisture - but not good moisture - so I am not expecting 100 per cent crop emergence. Of more concern are those crops already in the ground. They need moisture to keep them growing but if the weather stays like this the crop will not be good at all."
Andrew Williams, farm manager at Home Farm (Nacton) in Suffolk told Grower: "It's a job to keep up with the irrigating. We have already started irrigating early leeks, onion sets, potatoes and early brassica under fleece."
He added: "We have also had to water asparagus to tackle cut worm, which thrives in this sort of weather. Irrigating this early seems to be becoming a bit of a trend."
WHAT THE GROWERS SAY
"It's disastrous. We usually irrigate on marsh streams which hold a lot of salt that we flush out using water from a nearby river. But a road scheme is affecting access to the river. Our crops are suffering greatly. We are facing erratic crop germination and potential losses. Irrigation of our cauliflower was scheduled for the end of March. The other problem is asparagus. This does well in warm weather so there is a lot and everyone has it." - Peter Dyas, vegetable grower, Dyas Farms, Ramsgate, Kent