Wyevale Nurseries says the sales increase has been driven by demand from independent garden centres, trade customers and cash and carry.
Sales and marketing director Adam Dunnett said: "It’s fantastic news. March has been a great month for us and our best March since 2012 and in fact it is the best first quarter since 2012 with sales up 18%.
"Things are really picking up and the weather has certainly helped particularly in the retail sector.
Dunnett added: "Our emphasis on developing a 21st century plant range is starting to pay dividends and a resurgence in the popularity of shrubs in garden centres is helping too.
"We also saw big sale increases in transplants with buyers wanting to purchase British. This was the same with trees and we have also modernised our tree range and are growing much larger volumes of container trees."