The wet weather flooded the company’s peat bogs in the north of England but also affected supply beyond the UK, including Ireland, Scandinavia and the Baltic countries, leading to a European-wide shortage.
“The performance in the year ending September 30, 2012 has been badly affected by unprecedented weather conditions and is not a reflection of the long-term prospects of the business,” the company said.
The supply shortage will hit professional growers in the UK, who are particularly reliant on peat as a key ingredient in compost, and this will hurt the company’s revenues into next year, it said.
It added that its final dividend for 2012 is likely to be lower than last year’s 4.4p per share.
Chief executive Bernard Burns will step down as of early 2013 but will retain responsibility for the resolution of a complex compensation claim for the halting of harvesting at a now protected bog area in the north of Eng- land.
The specialist horticultural supplier made a pre-tax profit of £3.2m in 2011, on revenues of £54.3m. In September, it completed the £4.75m acquisition of a major new production site at Ellesmere Port in Cheshire.
Shares in William Sinclair were down 14 per cent to 140p at one stage yesterday.