In this blog post, we’ll be discussing how to fix 5 common leaf-related problems. Specifically, we’ll be addressing leaf curling, chlorosis, brown tips/edges, browning variegation, and yellowing. Note that the images in this post are not my own. They’re taken from the internet because I don’t have any plants which are currently presenting with these problems. Some of them aren’t the best examples for houseplants because I’m restricted by creative commons licensing, but they get the idea across clearly..
1. Leaf curling
Leaf curling is generally the result of lack of moisture for one reason or other. This could be due to under-watering, over-watering (resulting in root rot), or even severely lowered humidity. leaf curling is a clever evolutionary adaptation which allows plants to minimise water lost through transpiration, ad it reduces the surface of the leaf exposed to sunlight and dry air, and helps the leaves reabsorb moisture transpired from the stomata. Thus, when moisture is made sufficient through watering, plants should return to normal within a day. Leaf curling, in rare cases, can be due to fungal infection in indoor plants. In outdoor plants, it may be caused by pest infestations.
Chlorosis is simply when non-variegated plants produce growth that is lacking in chlorophyll. Chlorosis most commonly occurs when plants are placed in bright light but are lacking in nutrients in their potting medium. This is arguably adaptive, as it saves nutrients in a situation wherein light is plentiful so existing leaves are already able to photosynthesise adequately. Nonetheless, it is a sign that something is wrong and you should be using a fertiliser complete with trace elements in addition to balanced N-P-K. Even if you see chlorotic growth, do not use fertiliser at a stronger concentration than the recommended amount. Always follow the directions on the packaging of fertiliser. In fact, most recommend using fertiliser at half-strength. Chlorosis is caused by microbial infection or damage to the emerging growth in the early stages of its development in rare cases.
3. Browning tips/edges
Browning tips and edges may result from two probable causes: hard water or low humidity. If you notice the browning encroaching only from the tip, try to use softer water with less dissolved salts (eg. distilled water, rainwater, reverse osmosis water). If doing this for a while does not stop the browning from spreading, then raise the humidity. If the entire edges of leaves begin to brown, the chances are that if you raise the humidity, the plant will be fine. Common tip and edge browning issues involve leaf tips and edges turning brown and drying up. However, if you notice that your leaves are turning brown but seem droopy and moist rather than crunchy and dry, then something more sinister is afoot. I would suspect spider mites or fungal infection in this case.
4. Browning variegation
if you notice that the foliage on your plants is perfect except for the variegated parts, then it’s probably a combination of two factors: bright, hot sunlight and low humidity. These two factors cause the variegated parts of leaves to brown, as they burn more easily than the green parts of leaves, since they can’t effectively utilise sunlight for photosynthesis, meaning that if they sustain a little too much sun damage, plants tend to left the variegated parts die off, because they are ‘costly’ in terms of energy. This tends to happen less to pink, red or purple variegation, as they contain anthocyanin, the pigment that protects plants from UV damage. However, this is common in plants with white variegation. If you up the humidity and lessen the sun exposure and the browning continues, it may be a sign that your plant is simply adapting to your environment, and is stressed. Certain plants have a tendency to brown only in the variegated sections after shipping due to the stress.
5. Yellowing leaves
Yellowing leaves usually innocuous enough, especially when old leaves are the ones that are starting to yellow. When the oldest leaf is yellowing but the rest of the plant is in good health, it generally just means that the oldest leaf is no longer in tip top shape in terms of photosynthesising ability, be it because of biological, age-related degeneration, or due to wear and tear. This is a natural reaction to the leaf taking up space which could be used to produce an aerial root, so you don’t have to do anything about it. Clumping Syngoniums, I find, are particularly prone to naturally losing their oldest leaves. This makes a lot of sense in my head, since their new leaves get progressively bigger, blocking out the light for the older, smaller leaves. This effectively renders the old leaves useless, meaning that there is no longer any survival-related advantage to keeping them.
However, when a newer leaf yellows, it’s probably due to dehydration or a whitefly infestation. If the dehydration is caused by under-watering, simply water the plant. if it is due to root rot, simply place the plant in medium light, stop watering it, and maybe change the potting medium or take cuttings. Spray neem oil on the plant’s leaves in the case of a whitefly infestation.