Preventing legionnaires’ disease - advice for gardeners

Monday September 21, 2015

Legionnaires’ disease is a form of pneumonia. It’s caused by bacteria called legionella that lives in moist conditions. You can catch the disease by inhaling airborne droplets or particles containing the bacteria.

The illness may be mild but can sometimes be fatal. It is more common in older people, particularly if they smoke, have poor immunity or a chronic illness.
Symptoms include dry coughing, high fever, chills, diarrhoea, shortness of breath, chest pains, headaches, excessive sweating, nausea, vomiting and abdominal pain.

Anyone who gets these symptoms should see their general practice team right away and let them know if you have been handling potting mix or compost.

​Five simple steps to avoid Legionnaires' disease

Gardeners are at particular risk of catching Legionnaires' disease as the bacteriumLegionella can be present in potting mix and compost. The bacteria thrives in warm, moist conditions and can cause a severe, even fatal disease when contaminated particles or droplets are inhaled.

It is important gardeners follow five simple steps to avoid catching Legionnaires’ disease from potting mix or compost:

  1. Open potting mix carefully – use scissors instead of ripping the bags

  2. Wear a disposable face mask and gloves, and open the bag away from your face

  3. Do your potting in a well-ventilated area outdoors

  4. Dampen down the potting mix or compost with a sprinkle of water to reduce dust

  5. Wash your hands thoroughly after handling potting mix or gardening.

Man with mask potting plants in soil 


Legionnaires’ season arrives

The start of October corresponds with the beginning of Canterbury’s legionnaires’ season.

In October every year the number of people with Legionnaires’ disease begins to climb. Numbers peak in November and December, remain relatively high through January and February, and then taper off in March.

Graph showing legionellosis notifications 2010 to 2015 in Canterbury
Dr Ramon Pink, Canterbury medical officer of health, says the seasonal surge is mostly linked to gardeners catching Legionnaires' disease from potting mix or compost.

“After a long winter it’s great getting back into the garden and enjoying the warmer weather and longer days, but please make sure you avoid inhaling the dust from potting mix or compost as this can be dangerous,” Dr Pink says.

Page last reviewed: 03 December 2015