The study and survey of Royal Brompton and Chelsea & Westminster Hospitals found little evidence to support claims that flowers harbour dangerous bacteria, leading to them being banned from many wards.
In a study by Giskin Day and Naiome Carter of Imperial College, published on the medical website bmj.com, it was claimed that flowers could even help to improve a patient's health and recovery.
It had been thought that the water in vases used for flowers contained bacteria, but the research found no evidence that this had ever caused a hospital acquired infection.
Flowers were recently banned by Southend University Hospital on the grounds that they posed a health and safety risk around electrical and medical equipment.
But the report argues that flowers are no more dangerous than containers for food and drink in the hospital.
A staff survey found nurses more concerned about looking after the flowers than the risk to patients health.
Other studies have uncovered numerous health benefits in keeping flowers.
One found that patients in hospitals with plants had reduced systolic blood pressure and heart rate, lower ratings of pain, anxiety and fatigue and more positive feelings.
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