Research by the firm found that the contents of an average garden are worth £1,237, while one in ten features contents worth over £3,000.
Phil Loney, managing director of Lloyds TSB Insurance, said: "It's hard to put a price on the pleasure of a barbeque on a summer's evening but gardeners should stop to think exactly how much their backyards are worth.
"With all the gadgets and goodies that are available, they can quickly add up and gardeners run the risk of being under insured."
Leading DIY and garden centre retailer B&Q recently stated that home insurance is "very important" for homeowners.
The company added that the cover can provide help with protection in the event of accidental damage during renovations.
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