Q.water requirements for potted citronella/geranium plant
Plant is outdoors in partial sun/shade. Upon purchase, I replanted in larger container and mixed top soil with the original medium. If I wait too long to water, leaves shrink and collapse. After watering, brown dead spots appear on the leaves.
Generally potted plants outdoors need daily water and even twice daily if the temperatures are above 85 degrees.
The best way to check watering is to actually feel the soil. If the soil is damp when you feel just below the soil surface it is likely ok, if it is dry you need to water.
Make sure the pot is well draining.
The brown spots could be a fungus issue. You can treat the plant with Neem Oil. This acts as both an insecticide and fungicide.
https://www.gardeningknowhow.com/edible/herbs/scented-geranium/scented-geranium-care.htm
https://www.gardeningknowhow.com/edible/herbs/scented-geranium/mosquito-citronella-geranium-plant.htm
https://www.gardeningknowhow.com/plant-problems/pests/pesticides/neem-oil-uses.htm