Disease and Insect Prevention Tips for Keeping Healthy Houseplants

Disease and Insect Prevention Tips for Keeping Healthy Houseplants

Properly maintained houseplants in a healthy, insect free environment seldom fall victim to disease and pests. Often the damage inflicted by houseplant disease and insect infestation is the result of a lack of care and prevention. A few basic preventative measures can provide your houseplants with all the care they need to thrive and prevent disease and insect damage.

Do Your Research

The best way to ensure optimal growing conditions for your houseplants is to spend a little time researching houseplant varieties and their preferred growing conditions. Think about your home and where you place you plants. What are the conditions of the room? Is the room dry, humid, or somewhere in between? Does the room tend to be very warm? Is the room kept relatively cool for sleeping or does the temperature fluctuate? What kind of light is in the room and for how many hours of the day does it last? Consult plant guides and labels and choose houseplants according to their required growing environments.

TIP: Our expert gardening advisor, Rachel Klein adds, "Houseplants may live all year round, but they do have a dormancy period. When you notice they are not putting on new growth, water less and do not fertilize."

Get A Clean Start

Whether you are potting new plants, starting from seed, or transplanting an old standby for better living, be sure all your tools and pots are clean before you begin. This is especially true if you are using tools you also use for outdoor gardening. Tools, such as trowels and shears, should be washed in warm, soapy water. A little added bleach is a good idea too.

If you are transplanting into a pot you used previously for other plants, wash the pot to be sure all traces of insects and disease are gone. Scrub the pot with warm, soapy water and soak in a mild bleach solution of 1 part bleach to 9 parts water. Let the pot soak in the bleach solution for 10 minutes. Remove from the bleach and rinse.

Cleaning does not stop with just the tools and pots. Potting soil needs to be clean and disease free, too. Use commercially sold, sterilized soil labeled for houseplants and potting. Soil dug from a garden is not generally recommended, unless you are very skilled at adding the proper amendments such as peat moss and sand. Additionally, home prepared soil requires pasteurization to kill insects, bacteria and diseases that may be growing in it. Any material used in the bottom of the pot for drainage should be clean, too.

Provide Proper Drainage

Drainage is essential to growing healthy potted houseplants. Pots need holes in the bottom to drain excess water from the soil and to absorb water when watered in a bottom saucer. Pots and containers should have a layer of small rock or pebbles placed in the bottom of the pot before soil is added. It is a good idea to consult your plant's requirements.

Use Balanced "Soil"

The ideal mix for houseplants is actually soil-less. This potting medium will stay moist and drain quickly, boosting root health. Use a mix of perlite, peat moss, sphagnum moss, orchid bark, and charcoal.

Water Properly

Plants need adequate and regular watering according to each individual houseplant's needs. Again, consult labeling and guides to determine the appropriate frequency and amount of water for each plant.

TIP: Rachel suggests, "Always water with lukewarm water to avoid chilling the plant's roots."

Keep in mind that plants inside often dry out more quickly, particularly in the winter months when heating systems rob the air of moisture. Avoid overwatering of plants, which can cause fungus and mold growth, root and stem rot, and invites insects to breed and thrive on plants.

TIP: Rachel advises, "Some varieties of houseplants, including the very popular sanseviera, need only be watered once every 2 to 3 weeks. Watering more than this can be detrimental to their health."

To prevent rot problems, always water plants from the bottom when possible. Roots will suck up the water from a saucer beneath the pot through the soil.

TIP: Rachel recommends, "If you plan on watering your plants from below, do not include rocks and other drainage improvements because it keeps the soil medium from absorbing the water in the saucer."

Roots and stems in drenched soil rot in standing water. Low lying leaves touching wet soil rot and die and a plant without food producing foliage cannot survive. An excess of water or plant food is no friend to healthy houseplants.

TIP: "Watering your houseplants with tap water is fine, but occasionally water with distilled water to flush out the salts that will gather around the roots."

Any watering, and especially washing and spraying, is best done in the morning so that houseplants and foliage are dry come evening time. Molds and fungi thrive at night on damp, dark plants. Insects will use the wet, dark conditions to breed and reproduce. Eliminating optimal growth conditions helps to keep diseases and insects at bay.

TIP: Rachel adds, "Lack of humidity is one of he biggest problems for houseplants, particularly during the winter when heating systems dry air substantially. Houseplants that thrive in high humidity include orchids and ferns. Research your houseplant's ideal humidity conditions. To raise the humidity, set the pot on a saucers of pebbles that you keep moist. Also, mist your plants with a spray bottle of water once a week during the growing season."

Wash Your Plants

Regular plant washings in a sink with a hand sprayer prevents many houseplant disease and infestations as well. Dust that accumulates on the leaves of houseplants will block light and harbor insects. A weekly shower in the sink keeps many diseases and pests at bay, washing invaders down the drain. Once or twice a month, rinse plant foliage with warm water. You can add one drop of mild liquid dishwashing soap or insecticidal soap. If you do, make sure to rinse the plant thoroughly afterwards. The soap will help to kill disease growth and kill insects that resisted a simple plain water rinse.

Keeping pots clean and debris free prevents problems, too. Remove dead leaves from pots promptly where molds might grow and insects like to hide.

Large plants that cannot fit in the sink or are not easily moved should be sponged periodically. Wipe stems and leaves with a damp sponge for insect and disease removal.

TIP: Rachel suggests, "Large plants can also be brought outside and gently hosed off."

Pick the Proper Placement

Each plant has its own unique needs for water, light, and temperature for optimal growth. Placing plants in areas where they can grow and thrive keeps them healthy and able to stave off disease. In addition to adequate watering and light requirements, houseplants need air. Circulating air keeps foliage dry and healthy. Do not place plants so close that their leaves are touching; air will not get around the entire plant, leaving dark and moist sections prone to insects, molds, and fungi. Closely packed foliage also provides insects with abundant hiding places and moist conditions for breeding.

TIP: Rachel adds, "Some plants are very cold-sensitive. Make sure to move these houseplants away from drafty doors and windows during the winter."


The frequent watering required by some houseplants leaches nutrients out of the soil. Without these important nutrients, your houseplants could be more susceptible to disease and infection. Nutrients must be replaced by regular fertilization. Mix a balanced 20-20-20 fertilizer solution at half strength and feed your houseplants monthly during the growing season. Water soluble fertilizers are more effective than fertilizer sticks. Some fertilizers are made specifically for houseplants.


Any time a new houseplant is introduced into your home, it should be kept separate from your existing plants for a couple of weeks to be sure it is not harboring insects and disease. Keeping new plants in a separate room is best, but if that is not possible keep the plant at least 10 feet away from your other houseplants. This will make it difficult for insects and disease to jump to nearby neighbors and may save you from losing an entire roomful of plants.

Watch For Signs of Trouble

Periodically, look over your houseplants for signs of distress, disease, or insect activity. Catching a problem early may save the life of an infected plant, and removing it from a grouping will keep neighboring plants healthy.

When plants are moved for washing and watering, check leaves and stems for tiny, well hidden bugs. Be sure to turn leaves over and check leaf bottoms too. Often insect invaders make their homes on inconspicuous leaf bottoms or in crevices near stems. Aphids and larger insects will be visible with the naked eye; many common pests are very tiny and require a magnifying glass to see them.

Signs that you may need to more closely look for miniscule insects like mites and white fly larvae are deformed leaves and buds, curling or yellowing vegetation, stunted growth, and unhealthy stems. Spotty leaves or a scaly appearance may indicate the presence of tiny bugs. Check thoroughly with your magnifying glass to determine the problem and proper course of treatment.

TIP: Rachel advises, "Do you think your houseplant may be infested with soil gnats? To find out, slice a chunk of raw potato and lay it cut side down on the top of the soil where you suspect they are thriving. After a week, lift the potato up. If you have gnats, you will see larvae on the potato. To rid yourself of then, allow your plant to dry out to the point of wilting before watering again. Though it may look sad for some time, in the long run killing all the larvae with lack of water will be much more beneficial for your thirsty plant."

Many of the signs of insect infestation are the same or similar to the signs of houseplant diseases, fungi, and molds. The same unhealthy, yellowed or spotty appearance could be an indication of a fungal or mold induced illness. Black, mushy areas indicate a form of rot, likely caused by problems associated with overwatering or overfeeding. In the absence of a parasitic cause, consider likely disease offenders.

Sometimes plants can be treated by simply cutting away a diseased area, removing the source of the problem, or treating with home safe insecticides and anti-fungal solutions. If a disease or infestation is very bad, the best prevention to save your remaining plants is to throw out the diseased plant and focus your efforts on rehabilitating houseplants with only minor or moderate signs of affliction. Insects and diseases spread quickly among houseplants, and one too far gone will only encourage insects and diseases to find new hosts.

Houseplants are pleasing elements of interior decor, as well as natural ways to freshen and clean indoor air. What's more, houseplants are an interesting hobby. Proper houseplant care and disease prevention ensures your investment of time and money remains a source of enjoyment and not a cause for frustration.