Whether you are growing your green-leafed plants outdoors or indoors, when the leaf margins and tips begin to turn brown it is clear that something in the plant's environment is amiss. Brown leaf margins can be caused by a wide array of issues. Most problems can be deduced by careful observation of the plant and its environment and then easily remedied once identified.
Too Little Water
Plants receiving insufficient irrigation is the No. 1 likely cause of the leaves turning brown on the tips and around the margins. This may be because of to too little water being applied too infrequently for the plant's liking. It may also be a sign that the plant is root-bound and there is no soil or too little healthy soil to absorb and hold moisture against the roots, causing the plant to be under constant drought stress. Over watering, on the other hand, almost always manifests itself in fading or yellowing leaves or by the dropping of green healthy leaves.
Excessive Sun or Heat
Placement too close to glass windows, near heating vents or planting in a ground location where too much sun is received can all burn and desiccate the plant, causing the leaves to brown. If a plant that prefers light shade to full shade is planted in a full-sun exposure it is not conditioned to cope with that environment and will struggle to survive burn and rapid lost of fluids, causing the leaves to brown.
Overfertilizing plants or fertilizing too near the stem or trunk can cause chemical burns to the roots and stem. This stress or plant tissue destruction can choke off the flow of water and nutrients to the stem and leaves causing them to desiccate and brown along the margins.