Chairman Jim Floor said: "Sarah is very capable and this business needs very strong leadership.
"We'd quite like to take 2011 into a field and bury it. But for 2012 we have a good plan and the shareholders have been very supportive of the business in the past 12 months - 2012 is the year we have to deliver."
The German-owned supplier is launching a grower cooperative this year and expects six "fairly substantial growers" to join over the next six months.
Floor said January sales figures were on budget and waste was in line with budget. He said Landgard UK was putting "more science into budgeting" this year.
In 2011, bad debt from Focus of £2.5m caused Landgard UK managing director Richard Egerton to quit. A new IT system and cost-control problems also hit the business.
Floor said: "There's plenty of room for growth. We have a nice portfolio, from independent garden centres to DIYs and supermarkets."
He said rose sales were 20-30 per cent up and fruit trees were going well. The company has opened a cut flowers division.