Planted a new mint plant in a terracotta pot this spring. It has been on our automatic watering system all summer. It was fine initially but for some time has looked spindly, pale and has silver patches on leaves which then turn brown (patches, not whole leaves). No new shoots are appearing. No insects can be seen and problem doesn't look like rust. Help, please.
Mint Plant in Pot Looks Very Sick
Certified GKH Gardening Expert
My Mints will stop growing and look spindly when they are quite root bound and are laking soil and nutrients.
I would repot the plant and trim it up. I would increase the pot size by 1 to 2 inches.
Use a good quality potting mix with a good drainage hole.
I would also treat with Neem Oil. This works as both an insecticide and fungicide and is safe for people, pets and beneficial insects.
Here are some links for you.