Common Houseplant Diseases
By: Heather Rhoades
Plant diseases are harder to spot on houseplants than pest attacks. Usually when you do spot a problem, fungi is the major cause. Let’s take a look at some of the most common houseplant diseases so you can deal with them promptly.
Common Diseases of Houseplants
Here are the most common houseplant diseases that you may come across when gardening indoors.
Gray mold, or botrytis, is a common disease in greenhouses. It’s not that common inside homes, however. It starts on dead tissue like dead leaves or flowers. Once it starts, it will spread to the rest of the healthy plant. The affected parts of the plant will quickly be covered by fluffy gray mold growth, which gives off lots of spores when you handle the plant.
Gray mold is encouraged by damp, cool conditions. It tends to be more frequent in the fall months. Don’t water your plants late in the day if they are going to be subjected to fall night temperatures. Keep some ventilation going to keep a buoyant atmosphere. Make sure to remove all dead and dying parts of the plant when you see them to deter the mold from growing.
Both downy and powdery mildew affect plants. On indoor plants, you’ll most likely come across powdery mildew. It starts like a powdery white patch that grows larger until it covers the entire leaf surface. The plant foliage often turns yellow and falls, and it becomes quite obvious that the plant isn’t thriving. Hot, dry conditions favor this disease. Fungicides, like neem oil, can often help.
One disease that is difficult to control is rust. Pelargoniums, carnations and chrysanthemums are most commonly affected by rust. Usually, a pale circular spot on the top of the leaf is the first symptom. On the underside, you’ll find a rusty ring of brown spores.
There are a lot of symptoms you can find on the plants affected by viruses. These can include mottling or mosaic patterning of leaves, malformed leaves, misshapen flowers and bad coloring. You usually cannot control a virus by chemicals. These viruses are mainly spread by aphids, so you’ll have to dispose of the plant instead.
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Signs of Disease in Common Houseplants
Just like people or pets, houseplants occasionally succumb to disease. In the worst case, disease can kill a plant. But many times, if you know what to look for, you can spot warning signs of an outbreak and act to defeat the disease.
Many common houseplant diseases operate in an opportunistic fashion, taking hold when plants are stressed due to unfavorable growing conditions. The single greatest thing you can do to prevent disease outbreaks is to provide a suitable growing environment. This means using proper soil, not crowding plants, avoiding drafts, and providing adequate temperature, humidity, light, water and drainage.
To prevent listed insect, mite or disease infestations or to control them when they first appear.
Roses, flowers, houseplants, ground covers, vines, ornamentals, shrubs and trees. For use on non-edible plants only. Not for use on lawns.
Dilute 2.67 fluid ounces, 5 + 1/4 Tablespoons) concentrate in 1 gallon of water.
To treat an existing disease. To prevent and protect against future diseases.
Roses, flowers, azaleas, camellias, rhododendrons, landscape trees, shrubs, ground covers, vines & houseplants.
Add 3/4 fluid ounces (1+1/2 tablespoons) to 1 gallon of water.
Apply when listed pests are seen or found. Reapply every 7 to 10 days until infestation is eliminated. Do not exceed 0.4 lbs imidacloprid per acre per year. This can contains 0.00024 lbs of imidacloprid.
For use in outdoor residential gardens. Not for use on lawns.
Disease Symptoms: What To Watch For
When disease attacks a plant, it's easily visible. Growth slows, stunts or becomes spindly leaves may yellow, show white powdery blotches or develop spots. Affected leaves eventually drop. Stems may become soft and mushy, with black tissue visible near the soil.
Waterlogged soil – either from overwatering or compacted soil that lacks air pockets – causes roots to suffocate and die, trading their white tubular appearance for a spongy, blackened mess. Root problems usually surface as a plant that remains wilted, even though soil is adequately moist. Slip a plant you suspect is having root issues from its pot. Blackened roots and a sour or ammonia odor are sure signs the root system is unhealthy.
Learn to recognize these symptoms of common diseases.
Gray Mold: Also called Botrytis a fungal disease that can attack every part of a plant. Resembles fuzzy Gray Mold. To prevent, faithfully remove dead leaves or flowers from stems and soil, and provide adequate air circulation. Commonly attacks Begonia, African Violet and Cyclamen.
Powdery Mildew: White powder appears on leaves. Powdery Mildew doesn't kill plants, but greatly weakens them. Associated with poor air circulation.
Leaf Spot: Yellow, brown, black or water-soaked spots appear on leaves. When disease is severe, separate spots coalesce and kill the leaf. Also causes brown dusting on leaves and blooms. Frequently attacks Dracaena and Dieffenbachia. Associated with too-high temperature and humidity also with poor air circulation.
Root Rot: Early symptoms are wilting and yellow leaves. In severe cases, the entire plant collapses. Associated with poor drainage and overwatering.
Viruses: These diseases manifest as distorted, streaked or mottled leaves, or by diminishing plant growth and flowering. Most viruses are incurable – and many are contagious. If you suspect a virus, isolate the affected plant and provide perfect care to rule out other diseases.
Dealing With Diseased Plants
Follow these steps to prevent disease development and spread.
- Isolate diseased plants.
- Wash hands between plants when working with different houseplants.
- Sterilize tools between plants with a solution of 1 part bleach to 9 parts water.
- Provide adequate water – don't overwater or underwater.
- Double-check light needs adjust a plant's location accordingly.
- Avoid crowding plants. Ensure that air flows freely around plants. If necessary, use a small fan to improve airflow.
- Give up on the most diseased. Sometimes you'll need to toss plants you can't cure.
Bacteria are single-celled organisms that live on various kinds of organic matter. Unable to survive in the open, bacteria live inside plants and are transferred plant to plant by insects, water, and hands. Fungi are minute organisms that live on plants and cause visible symptoms. They spread most often via water, wind, and insects. Viruses are the smallest of disease vectors and the most difficult to control. Insects typically spread diseases, but some diseases are spread by seeds and tools.
Generally for a disease to occur, organisms must be transported to a susceptible host, such as a stressed plant. Ideal conditions (humid, dry, cloudy) make it possible for the disease to thrive.
Common House Plants
Most common house plants we know and grow are popular for two basic reasons. One, they're attractive, and two, they're easy to grow.
So many plants fit this criteria, that it's difficult to narrow this list to just a few. In fact, most in the House Plants Encyclopedia A-Z are common. (You'll find care tips for those shown here and many more in the Encyclopedia A-Z.)
Fortunately, common house plants provide us with a huge range of sizes, shapes, and textures to choose from. But why choose? Tall or trailing. broad leaves or feathery fronds. the contrasts look spectacular when brought together in a room.
Fiddle Leaf Fig makes a big statement in any room. Interior decorators are finally appreciating this tall beauty as an architectural feature. We're seeing this fig tree everywhere -- online and off.
Boston Fern is a classic. This is the most popular of the fern species that originated in Central America and became a fast favorite in parlors and porches in North America during the Victorian era.
Today, there are numerous new cultivars that are getting attention, including 'Fluffy Ruffles' with curly fronds and a dwarf variety 'Timii' that makes an elegant table accent.
Cascading stems covered with lush lobed leaves make English Ivy an ever-popular houseplant. New cultivars offer foliage variegated with creamy white or yellow, giving them fresh allure.
Whether you display your ivy on a pedestal by itself, surround it with other plants, or add it to a dish garden, its beautiful foliage is a stand-out.
Splashed with cream, green and gray, this Rubber Plant cultivar is stunning. Like other members of the ficus family, this big-leafed tree wants bright, indirect light. It's not as fussy as some about watering, but don't allow it to dry out or it will protest by dropping its leaves.
The glossy, deeply-veined leaves of the Peace Lily (shown at right) make it a beautiful foliage plant year-round.
It tolerates low light levels. But, give it bright light, and it will dependably produce long-lasting white spathes, each surrounding a spadix covered densely with its tiny, true flowers.
There are many hybrids to choose from. 'Domino' has beautiful marbled leaves. 'Mauna Loa' is a popular variety, treasured for its big, showy leaves and blooms.
Whether you call it Mother-in-Law's Tongue or Snake Plant, those common names don't give sansevieria the respect it deserves.
It's tall, sword-shaped leaves make stunning vertical accents among a group of leafy, bushy plants. And because of its ability to tolerate low light levels and low humidity, sansevieria is an extremely adaptable houseplant.
This hardy succulent originated in Africa and remains a favorite all over the world. You'll find it in homes, shopping malls and offices everywhere.
Umbrella-like foliage gives Schefflera the common name umbrella tree. It's easy-care and lush leaves make it a stand-out for indoor gardens. It's more tolerant of low humidity than most tropicals. Give it a quarter-turn in front of the window every week to expose all sides to indirect sunlight.
Spider Plant has slender, arching leaves with creamy white and green stripes. It has a trailing habit, making it ideal for a hanging basket.
Its spidery appearance comes from the small plantlets that grow on the ends of narrow, wiry stems, called runners.
These plantlets -- or "babies" -- are easily propagated, making this a plant that keeps on giving.
Several common house plants called ficus come from the Moraceae family. The elegant Weeping Fig is the most popular of all the ficus species from this clan.
Although slow-growers, you can expect the tree to reach up to 10 ft (3 m). Dwarf cultivars will grow to only 3 ft (90 cm) tall.
Weeping figs adapt best when placed in bright, indirect light and left there. It is known to drop its leaves when moved around. However, with good care it will grow new leaves in spring and summer.
Small, waxy leaves densely cover its drooping branches, giving it graceful elegance. Growers sometimes braid its trunks, adding to its charm.
Chinese Evergreen is ever-popular. You have a wealth of varieties of these common house plants to choose from, in many colors and patterns. Give them bright, indirect light to maintain their color and variegation.
Who hasn't grown a Heartleaf Philodendon? This happy-go-lucky vine tolerates low light and infrequent waterings like few others can. Even with little attention, it grows like nobody's business. Cut it back once in a while to keep it under control.
Or put it on a shelf or in a hanging basket and allow the thickly leafed vines to trail. This little philodendron thrives under fluorescent lights, making it a popular office plant.
Common Houseplant Problems
You might have been a diligent plant parent, but things can still go wrong, as when you are dealing with the natural world, some things are beyond your control. The only key to successful gardening is to pay close attention to the plants and learn from your mistakes. So, let’s discover some of the common houseplant problems!
#1. Leaves That Turn Yellow
Before you start to panic, let me inform you that it is completely normal for older plants’ leaves to yellow and drop off as it is part of their natural ageing process. However, if too many leaves are turning yellow, including new growth, then this could be a sign of a more significant issue. But the good news is that yellow leaves let you know that your plants need help.
Let’s trace back to the possible causes of yellow leaves:
- Poor drainage or improper watering: Sometimes, either too much or too little water can be the leading cause behind yellow leaves. For instance, when the soil is overly wet, the roots cannot breathe and due to suffocation, they stop transporting water and nutrients that plants require. This also applies for under watering, where plants cannot take up essential nutrients with too little water. As a result, leaves turn yellow.
- Root Damage: Once again, damaged roots cannot function properly and deliver necessary nutrients to plants, resulting in yellow leaves.
- Too much sunlight might be another cause.
#2. Edges of Leaves That Turn Brown
When your plant gets brown leaf tips, your first thought is that a disease or pest is attacking your plant. But that is not always the case. There are several reasons why this may happen:
- Inconsistent Watering: Brown-leaf edges are often an indication that you need to rethink the way you are watering your plants. The unsteady or too little water supply is one of the main causes of brown spots on leaves. For example, you can’t just go for weeks without watering then randomly surprise your plants with a well-intentioned deluge.
- Lack of humidity: Most houseplants are tropical plants and a low humidity in your house can cause brown tips on leaves.
- Salt built-up in soil: It is true that most potted plants need a little fertilizer once in a while but remember that more was never necessarily better and if you are feeding your plants with a too much salt, it can accumulate in the potting mix and cause brown leaf tips.
#3. Leaves That Fall off Your Plant
Do you constantly have to pick up leaves from the floor when you walk by your plants? Dropping leaves can be quite disheartening, especially if you don’t even know why it is happening.
Even though it is seen as completely normal for some plants to go through leaf loss, there are some other reasons that explain dropping leaves and they are not really good.
- Over watering and under-watering: Too much or too little water can affect a plant’s structure. And as a result, the leaves cannot support their own weight any more, leading them to drop.
- Weather and climate: Environmental changes can be one of the reasons for leaf loss in plants. For instance, sudden changes in temperatures, whether hot or cold, can lead to dropping leaves.
- Seasonal changes: We are all familiar with leaf loss in fall. But did you know that it can also occur in spring and summer?
- Pests and disease: There are some pests and diseases that can cause leaf loss in plants.
#4. Leaves That Wilt
Wilting leaves are a giveaway that something is wrong with your plant. There are numerous reasons why leaves may wilt:
We have a skeleton structure that helps us to stand straight. However, unlike us, green leafy plants don’t have
such structure and instead use water pressure to keep them standing straight. To understand this concept, let’s think of a plant leaf as being similar to a garden hose. When water is turned on, water pressure inside the hose is increased and the hose becomes stiff. But when the water is turned off, the hose becomes limp, like it’s wilted. This also applies to plants. If the roots don’t get enough water, they cannot maintain the plant’s proper water pressure, which leads to the leaves to wilt.
Roots can rot due to overwatering or certain diseases and as a result, the plant is affected and the leaves wilt.
Have you ever experienced these problems? Please share your comments!