What To Do If The Leaves On Your Petunias Are Turning Brown
By ALEXANDRA RODRIGUEZ
Petunias are prone to damage because of the climate. They thrive in low-humidity areas, so in a high-humidity environment, their leaves may turn brown.
To fix that, you'll want to change your watering schedule. Don't water your petunias for a few days to a week until their soil is dry, then you can begin watering them once a week.
If you're growing petunias outdoors in pots and the soil is still wet the following week, consider adding new potting mix with perlite or clay pebbles to allow the water to drain.
If you don't live in a high-humidity area but the leaves are brown, then overwatering may have damaged the roots, or the plant could have a fungal infection.
An easy way to tell if the roots are damaged is if the plant's base has brown spots. You'll want to remove the plant from the pot and prune the damaged roots before repotting.
If petunias have a fungal infection, you'll see mold growing on the stems or the base. Pruning 1 inch away from the mold with sanitized shears will help encourage new growth.