Allotment owners and gardeners hit by flooding have been warned against eating fruit and vegetable crops that could have been contaminated by sewage.

The Royal Horticultural Society (RHS) issued the warning as it set out advice for gardeners on coping with flooding, which is set to linger into the spring when people will be starting to sow and plant flowers and food crops.

The long-term effects of flooding on gardens should not be too bad, as long as the flood water was not seawater, the RHS said.

Chief horticultural adviser at the RHS Guy Barter said: "Once the water goes down, the soil will be ready to sow and plant after a few days.

"There could be rubbish to pick up and people have got to be aware of contamination from sewage, and they will want to take appropriate precautions for that.

"The soil won't be damaged beyond repair, although nutrients will be washed away so investment in fertilisers is a good idea.

"But if we get an average spring and summer there should be no long-term consequences."

Edible crops close to being harvested should not be eaten in case flood water was contaminated, the RHS advised.

Crops that are eaten raw should not be harvested for another six months, although the experts said it was best to avoid growing salads and uncooked crops in flooded land for two years to avoid the risk of disease spores.

But crops such as root vegetables which are cooked before being eaten are safe, and fruit from trees and bushes that stand above the water will also be safe to consume, the RHS said.

Rubbish left in gardens after the floods recede should be put out in the household waste or bagged up and taken to the local waste disposal site.

Gardeners are also being urged to make sure products such as greenhouse paraffin, fertilisers and pesticides are put where they cannot cause pollution.

And electricity in sheds and greenhouses should be disconnected if it is likely they will be flooded, and not switched on again until it has been checked by a qualified electrician.

Ruined plants can be dug into the soil or put in the compost bin, the RHS said, but fertiliser or mulch should not be put on the soil when it is saturated as it may cause pollution or be wasted.

The experts also said that where it looked like there would be serious delays in the soil drying out, gardeners should sow plants in pots and seed trays on the patio, at home and or window sills or buy plants in from nurseries so they can get them outside in mid-spring.