HTA Amenity Suppliers Group chairman Tim Edwards said: "De- mand is holding up well and prices have increased, especially for larger trees. With ever-rising costs and the strong euro, prices are likely to continue to rise and need to do so to keep up.
"But the impact of the economic situation is starting to be felt and the sector predicts a drop in sales, especially for housing projects in 2009," he added.
The HTA's annual survey of 60 per cent of the amenity supply market revealed a seven per cent increase in the trade of plants with a 19 per cent increase in their value. There has been more demand for 12-16cm girth trees.
Crowders Nurseries sales office manager Tom Owen said: "We see a lot of enquiries for more mature stock; it's about the visual impact, particularly in city centres and shopping parks. People aren't willing to wait for things. But from summer 2009 we may see the problems with the economy affecting us."
Demand has reduced for shrubs of four to 10 litres but the value of the product has increased dramatically - up 35 per cent in 2007 to £8.56.The HTA survey showed there has been a move in the market towards specimen shrubs in large pots and the volume of shrubs over 10 litres has increased by a third.
This has been accompanied by a seven per cent increase in selling price, taking it to an average of £16.67.
The majority of plants grown by the amenity sector go direct to landscape contractors, who account for 62 per cent of the market by value. The value of products going to trade cash and carry has increased its market share from one per cent to three per cent.
The HTA survey also revealed that shrubs under four litres have seen a 32 per cent increase in value since 2006/07, while four- to 10-litre shrubs have 35 per cent increase in value during that period.
Other figures show that shrubs over 10 litres have seen a 33 per cent increase in volume sold and there has been a two per cent drop in demand for herbaceous plants.