The leaves on your philodendron can start turning black for a variety of reasons. Some are due to environmental factors, while others aren’t.
In most cases, you’ll be able to save your philodendron with black leaves, and I’ll show you how.
Bacterial and fungal leaf spots are the leading causes of philodendron leaves turning black. You should also watch out for improper irrigation, sunburns, pests, soil salt build-up, low humidity, and environmental issues. Good watering habits, proper lighting, and adequate humidity are great prevention measures.
In each scenario, prevention is the best policy. Read on to find out more about how to treat and prevent each case.
Causes of Philodendron Turning Black
Given that philodendrons are native to tropical climates, they prefer humid environments. However, humid conditions are sometimes hard to emulate indoors.
Unfortunately, low humidity speeds up moisture loss through respiration and evaporation.
With time, the leaves will wilt, crisp up, and turn black. And eventually fall off, if left untreated.
In addition, low humid areas are usually dusty and dry. Dust may collect on leaves, hindering them from absorbing moisture from their surroundings.
This results in your philodendron having black or dark brown spots.
First things first, you’ll want to get rid of heavily blackened, diseased, and affected parts
Group healthy houseplants around your philodendron to create a humid microclimate
Ideally, you should use a humidifier or humidity tray (with pebbles) to increase relative humidity to the ideal range of between 65% and 80%.
If your philodendron is subjected to intense heat, this potentially could cause leaf damage and turn black.
It could be due to being placed closer to a radiator, boiler, fireplace, or heat vents. Exposure to scorching direct sunlight could also be to blame for heat stress.
Don’t forget heat accelerates the loss of moisture through evaporation and respiration. It may also cause heat buildup in the roots. This hinders the roots from absorbing nutrients and water.
As a tropical plant, your philodendron is more likely to succumb to heat stress, especially when combined with low humidity and excess direct sunlight.
Your philodendron will do well in temperatures of at least 70°F (21°C). However, you must avoid exposing it to too much heat or too much direct sunlight.
Move your philodendron to a spot where it’ll get bright indirect or filtered light. Make sure it’s away from heat drafts and heat reflective surfaces.
Hot and cold drafts, particularly sudden increases and drops in temperature, will cause leaf tissue damage.
They may also cause moisture to leach out of your philodendron, turning leaves black. Any temperatures below 50°F (10°C) will jeopardize the health of your houseplant. ( Source: University of Florida)
In the early stages, both the stems and leaves will shrivel and turn brown. If the draft isn’t rectified, continued damage and moisture loss will cause the leaves to blacken.
Philodendron prefers temperatures in the 70-80°F (21-27°C) range. Make sure the room is well-aerated and temp remains fairly constant.
Move your philodendron away from sources of drafts. These may include frosty windows, radiators, heat vents, entry doors, attic hatches, chimneys, and so on.
As with heat stress and drafts, sunburns can cause leaf damage and excessive loss of moisture. As the moisture continues to leach away, the leaves will wilt, dry out, and turn brown.
Remember sunburns also rev up the loss of moisture from the soil. Continued rapid loss of moisture will eventually cause philodendron foliage to go black.
If your philodendron is exposed to full sun for long, the stems will develop splotchy black markings. This is usually a normal response to sunburn and doesn’t exhibit any signs of pest or disease invasion.
Philodendron plants are happier in areas that receive medium-light to bright, indirect light. If you note that it’s turning black, take it to a spot with less light. Preferably, this would be a north-facing window.
Root Rot and Stem Rot
If the blackened leaves are on the low stems, your philodendron may be suffering from a stem rot or root.
You may notice that the stems are mushy, soft, and slimy, especially nearly the base where they meet the soil.
Root rot and stem rot are a sign of fungal infections, both of which are usually caused by poor watering habits.
Stem rot is due to prolonged damp or wet leaves and stems due to overhead watering or waterlogged soil.
Root rot is a sign of a waterlogged potting mix. Poor drainage, overwatering, and other bad watering practices can be to blame.
You must trim away all diseased stems, roots, and other affected plant matter.
In some severe cases of stem rot, the damage may be too extensive for your philodendron to be saved. Isolate immediately, consider propagation, and dispose of the diseased plant properly.
Otherwise, treat your philodendron with an organic fungicide or hydrogen peroxide then re-pot with a fresh, sterile potting mix.
Surprisingly, philodendron is a pest-hardy plant compared to most houseplants.
However, considering its high-growth nature, it can sometimes get infested by dust mites. You may also spot some spider mites underneath their leaves.
If left unfettered, these sap-sucking bugs can cause extensive damage to the leaves. At first, the leaves will develop small brown spots.
These spots will grow bigger and become darker, resulting in large black blotches. Eventually, almost the whole leaves will curl up and turn black.
You can easily get rid of dust mites by giving your plant a strong blast of water spray. This will help wash off the mites from the leaves.
Consider wiping the mites off using cotton swabs containing alcohol.
Several rounds of a weekly or biweekly spray of water and rubbing with alcohol should do the trick.
Philodendrons are susceptible to a few fungal and bacterial diseases that cause leaf damage.
A philodendron with this fungal disease will first develop yellow leaf margins. The leaves will eventually wilt, die, and turn black. In severe infections, the whole leaves will fall.
– Fungal Leaf Spots
The most common type that affects philodendron is phytophthora leaf spot. It’s often typified by dark brown, water-soaked, and odd-shaped lesions. The spots on the leaves will gradually turn darker and coalesce into large, black patches.
Common symptoms include:
- Yellow leaves
- Signs of root/stem rot
- Brown spots with yellow halos
- Black spots mostly on the leaf underside
– Bacterial Leaf Spots
Bacterial leaf spots on philodendron manifest as brown or black spots. If you’ve treated the disease with a fungicide to no avail, that’s a bacterial leaf spot.
Sadly, bacterial leaf spots are rarely irreversible or treatable. For this reason, you must prune away any diseased parts immediately and repot with fresh soil. In a severe case, consider propagation.
Most cases of fungal diseases can be treated with reliable sulfur or copper-based fungicide. You may also use hydrogen peroxide.
Improve aeration around your philodendron and practice good watering habits.
Even if it’s a tropical plant, philodendron hates standing on “wet feet”. They love the soil to be moist but not wet or soggy. In fact, they prefer the soil to dry out a bit in between drinks.
If the soil remains soggy, the roots will suffocate and die. That means your philodendron won’t be able to take up water and nutrients.
At first, the leaves will show signs of yellowing. When root rot sets in, the leaves will start wilting, curling, and drooping.
Small brown spots will develop along with brown leaf tips. Eventually, these spots will merge into larger, dark, or black blotches.
Check the soil for signs of waterlogging. If the overwatering case is mild, stop watering immediately and move your plant to more light to speed up soil drying out.
If the case is severe, tip your philodendron out of the pot. Inspect the roots for root rot. Now, if root rot is present, wash off the soil, treat the roots with fungicide, and repot with fresh soil.
Over Drying the Soil
You must water your philodendron regularly for optimal health and growth. If the soil dries out completely for long, your plant will become severely dehydrated.
Continue water loss due to transpiration, evaporation, and respiration will cause leaves to wilt, turn crispy, and become blackened.
Besides underwatering, low humidity, too much sunlight, excess heat, poor quality soil, and undersized pot may cause the soil to dry out faster.
You must water your philodendron immediately, deeply, and thoroughly. Make sure water oozes out of the bottom drainage holes. Your plant should soak up water for approximately ten minutes then empty out the saucer.
In the future, check the soil moisture every four to five days. If the top inch of the soil is still moisture, check back again in a couple of days. Water when it has dried out a bit.
Sure, your philodendron needs frequent fertilizing. However, too much of a good thing can do more harm than good. Overfertilizing your philodendron will cause leaf tips to curl up and turn brown and eventually black.
You’ll probably see white or gray spots on the soil surface. That indicates fertilizer salt buildup. Excess fertilizer salts cause severe leaf damage and blackening.
I also highly recommend scraping off salts from the soil surface. Repot your philodendron with a fresh batch of the potting mix if the fertilizer burn is too severe.
You must feed your philodendron roughly once every month during fast-growth periods. This should be early spring through the end of summer.
Use liquid houseplant fertilizer, making sure to cut recommended dosage by half.
Lack of Nutrition
Philodendrons are fast growers and they need proper feeding accordingly. If the soil lacks essential nutrients, malnutrition will cause your plant to discolor, experience stunted growth, and become blackened.
When affected by potassium deficiency, for instance, your philodendron will sport yellowed leaves with scattered black or dark brown spots.
Extreme deficiency will cause distorted growth and all leaves will curl and yellow with black patches.
You must fertilize your philodendron once every month from spring through summer. This should coincide with blooming and growth periods.
If the soil is spent, repot with a new batch of potting mix. Add some vermiculite to inject a dose of potassium.
Salt Build-up in Soil
As we’ve mentioned, excess salts in the soil will cause leaf damage. It hinders the normal absorption of nutrients and water.
In due time, the leaves on your philodendron will show signs of scorching – wilting, drying out, and falling off.
Depending on the severity of the salt burn, the tips or the whole leaves will shrivel and turn black.
Inspect the surface of the soil and you’ll likely see white spots – which signify salt buildup. It can be from softened water, tap water, or poor water quality.
For a mild case of salt build-up, flush water through the potting mix to leach away excess salts. Don’t forget to scrape off salts from the surface of the soil.
In severe situations, you must use a fresh potting mix to repot your philodendron.
Improper light will cause your philodendron leaves to blacken and drop off prematurely. While too much light (sunburn) is most likely, this can happen if you give it too little light.
Low light causes the leaves to lose green color pigment (chlorosis). That means your philodendron isn’t able to photosynthesize enough food and generate enough energy.
This causes the leaves to curl, become feeble, and yellow with brown or black spots.
Don’t forget that low light exacerbates the effects of overwatering, root rot, and diseases. All of these lead to the blackening of leaves.
Simply move your plant to an area with bright, indirect light. This usually means parking it close to an east-facing window.
There are numerous environmental problems that may cause your philodendron leaves to turn black. These include poor soil water retention, damaged roots, and too crowded roots (due to smaller pot).
The best solution is to address the environmental issue individually.
How to Prevent Blackening of Philodendron
- Keep your philodendron out of scorching direct sunlight, heat waves, and cold drafts
- Avoid or minimize overhead watering
- Water your philodendron once every 1-2 weeks when the top inch of the soil has dried out and isn’t wet.
- Prune your philodendron often in spring and summer — this will encourage healthy growth, increase aeration, and keep off pests/diseases
- Fertilize your philodendron once every month in spring and summer using half-strength houseplant liquid fertilizer
- Use humidifier, humidity tray, or misting spray to ensure relative humidity of 65-80%
- Provide plenty of medium to bright, indirect light