17+ Brown Spots Under Mint Leaves. I have cut off those leaves with brown spots for now. Mints will also turn yellow and become sparse when it is pot bound.
One of the young plants even has brown spots. When the skin is rubbed repeatedly it often develops hyperpigmentation. I don't think all of the brown spots can be explained away by rubbing against stuff though.
Black spots on the underside of the leaves can also be seen.
Usually the plant has been overwatered or it has been in full sun in summer. If you drink it after meals it can help aid in digestion since menthol stimulates bile flow. Freckles are flat, round and brown tiny spots that appear on the skin. However, it is sometimes caused by bacteria and other times caused by insects mimicking however, if you notice lots of leaves falling off, you may have a problem as only more established trees could tolerate this dramatic shift.