Citronella Plant (Mosquito Plant)

The spots on your P. citrosa ( this particular cultivar pictured is also known to some as Citronella, (almost never if ever blooms) is most likely caused by the pH of the soil that the plant is in. Geraniums (Pelargoniums) are allergic to Iron in the soli they grow in. When the pH is too acidic with a pH below 6.2 the Iron that is 'tied up' in the soil particles has its bonds released and enters in the soil liquid solution. The plant takes up the excess iron and shows its unhappiness with brown pimple spots on the leaves which sometimes look like spider mite damage. Leaf edges can also become a discolored brown. Fix it with bringing up the pH with a small dose of hydrated lime ( the very white fluffy lime) of a tablespoon or 2 sprinkled on the soil and water in. To prove the fix first get a pH reading of your soil at the plant in the ground as well as a mixed sample of the 2 pots' soil. If around 6.7 to 7.2 then any geranium, marigold, or Pentas plant will thrive for Iron (Fe) will be bound to the soil particles again. Lock 'im up , DANO ! Iron is a toxin to all those type plants; . Marigolds look like spider mite damage while Pentas begin yellowing leaves, edge burn, and leaf drop in low pH. Sweeten the soil with lime in the pots the same . Check pH in 2 weeks or so. Prove the test ! Happy gardening with less mosquitoes !