The group, which counts The Garden Centre Group, Wilkinson, Homebase and B&Q among it customers, said its net debt has been reduced by £1.7m to £7m.
Net assets have increased £1.5m to £15.9m.
Sinclair said peat stocks are sufficient to meet expected demand in the 2010 season against a background of predicted industry-wide shortages.
CEO Bernard Burns said: "We have made real progress in the past 12 months in delivering on our strategy to become the most efficient producer of growing media to the retail and commercial sectors in the UK.
"Through careful management, we have improved our performance, eliminated some business risks and made progress in bringing innovative new products to market.
He added: "If sterling remains weak as predicted, the UK professional growing market has the potential for an excellent year as imports will be more expensive. We could see increased demand from this market segment as UK growers gear up, with the potential for price increases and better margins.
"I believe that William Sinclair is best placed within the industry to prosper in this new market and consolidate our position as the lowest cost producer and market leader of peat substitute growing media. Taking all of these factors together, we look forward very positively to the coming year."
• See growing media feature in Garden Retail magazine, published on 22 January.
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