ANYONE inspired by the Chelsea Flower Show to get to work in their garden would be wise to check their insurance first. A third of home policies do not cover plants and landscaping, and the protection offered by most others is very limited.

According to financial information firm Defaqto, only 52 per cent of policies include plants as standard, with a further 14 per cent providing cover as an optional extra.

The average sum insured, automatically or as an add-on, is £2,350, compared to a typical starting cost of £7,000 for landscaping. Some policies pay a maximum of just £350.

The remaining 34 per cent do not insure plants at all, leaving householders with no recourse if they are damaged or stolen.

Sheds, garages and other outbuildings may be under-protected too. A survey for M&S Bank put a price tag of £567 on the contents of the average shed. When the value of lawnmowers, barbecues, tools and other items are added together, it can run into thousands.

While 60 per cent of policies limit claims for outbuilding theft to between £2,000 and £5,000, 12 per cent will only pay £500 to £1,500 – and three per cent do not cover this at all.

Cyclists need to be particularly wary of making assumptions about their insurance. Home contents policies may include bikes, but this is generally capped at a low value.

They may also be included in optional personal possessions cover, but for more-costly bikes it can be wise to take a separate cycle policy. Prices and cover levels vary dramatically, though, so it is important to shop around.

M&S said that more than a quarter of those with sheds report that they or someone they know has suffered theft or damage. Meanwhile, nearly half admitted that items stored there either were not covered by their home insurance or that they did not know if they were.

Brian Brown, head of insight at Defaqto, said: “Whether you’re a prize-winning gardener or not, there’s a lot of value to be found in gardens, garages and other outbuildings.

“However, not all contents insurance policies will provide sufficient cover for this, and if the value of items in an outbuilding is particularly high, it’s worth letting your insurer know so they can adjust your policy accordingly.

“In addition, remember that insurers will expect you to take reasonable care of your belongings, so make sure that sheds and garages are kept locked, otherwise claims may well not be paid.”

The problem of lack of cover is not confined to gardens. Insurers’ body the ABI calculated that one in five UK households is under-insured and Direct Line claimed the situation may be even worse among those in higher income brackets.

The policy provider said that 52 per cent of its home appraisals reveal the owner was previously under-insured for buildings or contents or that they had under-estimated their value on applying for a policy.

Nick Brabham, of Direct Line, said: “Far too many people are under-insured and could find themselves out of pocket, unable to repair their homes or replace cherished items, if a disaster were to strike such as they were burgled or their home was flooded.”

The ABI values the contents of the average three-bedroom home at £55,000.

If you make even a relatively small claim and your provider decides you do not have enough cover for all your possessions, it is likely to reduce the payout proportionately and could turn you down altogether.

To ensure you are fully protected indoors and out, make a full inventory of each room, your shed and any other outbuildings, and work out the approximate total value, including the cost of reinstating plants, garden furniture, statues and other features.

Check the small print of your policy to see what is currently covered and if it is not enough contact your provider to arrange an increase. Also make sure you know your excess – the amount of any claim you would have to pay yourself – and if it feels too high, adjust it.

If you are not happy with the revised terms quoted by your existing provider, go online and use price comparison sites to find alternatives at renewal time, including policies that offer unlimited contents cover.

An insurer may also reject a claim if it decides you contributed to the problem by taking insufficient care of your property.

To ensure you do not end up in this position, review your security, improving locks on doors, windows and gates as necessary. When not in use, ensure outbuildings are locked. Put bikes and other precious items inside overnight, and fit blinds to windows so thieves cannot see in.

Installing movement activated security lights and planting a prickly hedge around the garden can also help deter intruders.

Never leave spare house keys under doormats, in plant pots or anywhere else – there is no hiding place thieves cannot find. Keep car keys out of sight too, to reduce the chance of burglars making off with your vehicle as well.

Mr Brown said: “With sunny days ahead, many people will be spending more time in their garden. However, don’t let the sun get to your head too much, as one in ten insurance policies do not provide any cover for damage or theft of items which are not ordinarily left outside, so make sure you tidy and lock up properly to avoid losing out further.”