Leaf-tip browning is an annoying condition that commonly affects certain types of houseplants. Spider plants, tropical plants, and those with long, strappy leaves are especially susceptible. The main difficulty when confronting leaf-tip burn is to remember that it's a symptom of a larger problem (usually a cultural issue) as opposed to a condition in itself. So once your plant has burned leaf tips or margins, there's no way to reverse the damage at that wounded location. The only thing to do is correct the underlying problem and hope the plant continues its healthy growth.
The other problem with a leaf-tip burn is figuring out which of the possible factors may be causing it. Is it the water? Your fertilizer habits? What about the humidity? You might not know right away, so the best idea is, to begin with, the most likely condition, change it to the extent possible, and wait to see what happens. If new growth is unaffected or the scorching stops, you've figured it out. If it continues, then move on to the next condition and work on that.
Ideally, you'll catch leaf-tip burn early enough that the plant's appearance won't be completely ruined.
These are the factors that can potentially cause leaf-tip burn:
Leaf scorching can be a sign of erratic or insufficient watering or low humidity. It is especially true for tropical plants, which dislike the parched conditions in most centrally heated homes in the winter. These plants are evolved to luxuriate in humidity levels that range between 60 and 100 percent in their rainforest homes. A wintertime home can easily go to 20 percent humidity, which can cause leaf scorching. The solution is to raise the humidity—mist the plants, use a pebble tray, or relocate the plant to an area with higher humidity such as the kitchen or bathroom. Also, remember that plants with strappy leaves have a greater challenge to move water from the roots to the ends of the leaves, so these plants are likely to show leaf-tip scorching faster than plants with shorter leaves. Finally, if you suspect your water is highly alkaline (a pH above seven), consider finding a more neutral water source. Plants prefer a slightly acidic environment.
Fertilizer salts can cause leaf scorching, especially if large doses are fertilizer are applied. If you notice scorching on your plants shortly after feeding a heavy dose of fertilizer, it might be a problem with your fertilizer. Flush the soil with clean water several times to remove accumulated fertilizer salts and be more careful in the future.
Closely related to water stress, many houseplants aren't acclimated to cold, drafty conditions (by a winter window, for instance). Cold damage often shows up in the extremities first, meaning the leaf margins and leaf tips. If your tropical plants suffer from leaf scorching during the winter months, try to raise the temperature (and humidity, most likely) around them.
Sun damage usually shows up as yellowing of the whole leaf or even scorched spots on the leaves. Nevertheless, if your plant has recently been subjected to a change of direct light it's receiving, this could be the culprit. Having plant leaves against a window can also cause leaf scorching due to the window's ability to magnify and radiate heat.
Chemical damage is less likely to result in leaf scorching, but it's possible. Household pesticides and cleaning chemicals can burn plants in some cases, so be aware of what you're using on your plants.
Ultimately, a leaf-tip burn is almost always a cultural problem—fungal and bacterial diseases are typically more widespread across the leaf surface and usually involve the stem as well. So the best way to correct leaf-tip burn and margin scorching is to ask what cultural conditions might be causing the condition, then making an effort to fix them.
Diagnosing Poor Plant Health. Pennsylvania State University Extension, 2011
Yellow Leaves Can Indicate Plant Problems. University of Illinois Extension Website