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Roses – organic control of black spot and powdery mildew

Baking soda is a godsend in the kitchen and laundry but is less well known as an organic control of rose diseases, especially powdery mildew and black spot.  Try this baking soda spray on your roses.  It is used by enthusiastic rose growers around the world.  This recipe is adapted from the recipe that came my way from Tommy Cairns a world acclaimed rosarian who passed it on to my husband Graham Williamson, a well known New Zealand rosarian and recently turned rose breeder.


1 Tbsp Baking Soda
1 Tbsp Sprayfix ( or unperfumed liquid soap)
1 Tbsp Canola oil

  1. Shake vigorously
  2. Add to five litres water
  3. You need to keep agitating the mixture to stop it settling out
  4. Spray every 10 days