How to Care for House Plants

House plants are a nice addition
to the home. See more pictures
of houses plants.

The beauty of a garden doesn't just have to belong outside. You can bring the color, freshness and vitality of plants inside with house plants.

In this article, we will talk about lighting house plants, watering house plants, humidity for house plants, temperature for house plants, fertilzing house plants, potting house plants, grooming house plants, propagating house plants, decorating with house plants, preventing pests and diseases in house plants, and vacation care for house plants.

Scientific studies show that people are calmer, more efficient, and more satisfied with their lives when they have living plants around them. Tending to plants is known to be therapeutic, with beneficial effects on both our physical well-being and our mental health. There is also more and more proof that green plants filter common pollutants from the air around us.

Literally millions of house plants are sold across the country each year. Interior decorators feature them in all rooms of the house, and home decorating magazines never show a finished design without them. Indoor plants are readily available in nurseries, plant stores, supermarkets, and department stores.

Fortunately, growing house plants indoors isn’t difficult. In fact, it can be surprisingly simple. Armed with the knowledge of certain basic techniques, anyone can succeed in growing house plants. Learn how to use light for house plants in the next section.

Want to learn about house plants by type? Try these:

Lighting House Plants

Green plants live off light the way animals live off food: They absorb it and convert its energy into the sugars and starches they need to grow and survive. Without adequate light, no plant can thrive.

Fortunately, house plants tell us when they are not getting enough light. Their growth will be pale, and they will stretch toward the nearest light source. Flowering will be weak or totally absent. It becomes impossible to water them adequately: Without sufficient light, they can’t use the water we supply, and eventually rot sets in.

Southern exposures get full sun from late morning to mid-afternoon.

The light needs of different house plants vary. What may seem like a dark corner to a flowering house plant may be perfectly acceptable to a foliage one. Whatever your conditions, as long as enough light to read by exists, certain house plants will thrive there.

Seasonal Differences

Light intensities vary according to season. A south window, which may be too intense for many foliage house plants in the summer, is the best location for most house plants during the winter months. During the summer, move plants back from hot south or west windows, or draw a sheer curtain between them and the glaring sun. A north window, on the other hand, may not receive enough light for flowering house plants during the winter, but almost every house plant will thrive in its cool brightness during the summer months. Never hesitate to move house plants from site to site according to season.

Improving Natural Light

If your house plants show signs of lack of light, you can increase the intensity they receive by removing any obstacles that block the path of the light: for example, curtains, blinds, and outdoor foliage. Even cleaning the windows regularly will help. Another easy way of improving light is to paint nearby walls and furniture in pale shades, so they reflect light rather than absorb it.

Artificial Light

House plants adapt perfectly well to growing under artificial light. Incandescent lamps, however, even those offered for plants, produce light of poor quality that promotes weak, unhealthy growth. They are only good choices for house plants receiving some natural light. Fluorescent lights and halogen lamps, on the other hand, produce light so close in quality to sunlight that house plants will thrive under them. For best results, use artificial light on timers set at 12- to 14-hour days and make sure the lamp is far enough from the plants so they don’t overheat.

Window by Window

Light exposure varies among the windows in your home.

South Window: This is the sunniest exposure, getting full sun from late morning to mid-afternoon and bright light the rest of the day. Such locations will especially suit flowering house plants and those from arid climates, like cacti and succulents. Plants can usually be placed quite a distance back from a south window and still get very good light.
East Window: This location is often considered the best for growing house plants. It receives full sun for a short period in the morning and bright light the rest of the day. Cooler than a west window, it allows house plants to get the bright light they need without danger of overheating. Both foliage and flowering plants thrive here.
West Window: Like an east window, the west window receives full sun for part of the day and bright light for the rest. Its main disadvantage is that many house plants find such a spot a bit hot for their tastes. Both foliage and flowering plants thrive here.
North Window: House plants in north windows receive no direct sun, but, depending on the season, can receive bright light for much of the day. Generally speaking, only foliage plants will thrive here and even then, they must be grown close to the glass.

In the next section, we'll talk about watering house plants.

Want to learn about house plants by type? Try these:

Watering House Plants

Most house plants like their soil kept evenly moist, that is, neither soaking wet nor bone dry. A few prefer that their soil dry out entirely between waterings. No matter what the watering needs of a given plant may be, always water thoroughly, then wait until the plant needs more water before starting again. You can either use tepid water straight from the tap or let water stand overnight. In areas where water is very hard or where water is artificially softened, rainwater is often the best choice for watering your house plants.

How to Tell if Your Plant Needs Water

Plants will often tell you they need water by dramatically collapsing, but it is best not to wait that long, since most plants never recover from severe wilting. Learn to judge your house plant’s needs by checking it every two or three days.

Pour out excess water from the saucer after watering house plants from below.

There are various ways of telling if a house plant needs water. Some people go by soil color: The mix changes from dark brown to pale beige as it dries out. This is not always an adequate factor, especially for house plants in large pots. The soil at the top of the pot can often be quite dry, while that in the middle is still moist. For that reason, many people prefer sticking a forefinger into the mix. If it feels dry to the touch one inch down, it is time to water. There are moisture meters available that can also test for water needs. Other people prefer to lift the pot. When it approaches dryness, a pot will weigh considerably less. Choose whichever method best suits your needs and stick with it.

Watering Basics for House Plants

Most people prefer to water from above. In that case, water thoroughly until excess moisture runs out of the bottom of the pot. If the plant has dried out entirely, to the point of wilting, this method may not be sufficient, since dry soil often repels water. In that case, set the pot in water until it soaks up all it can hold.

You can also water from below. In that case, fill the saucer with water and wait about 20 minutes. If there is still water in the saucer at that time, pour it out. If there is no water in the saucer, the plant might not have received enough. Add more, come back in 20 minutes, and pour out any excess water.

For house plants that like their soil moist at all times, wicking can be a solution. All this requires is a water reservoir (an old margarine container, for example) kept next to the plant and a piece of yarn. Insert one end of the yarn into the top of the potting mix, pushing it down into a drainage hole using a knitting needle. Punch a hole in the lid of the reservoir and insert the other end of the yarn into the reservoir. Water once from the top of the pot to allow water to soak through the wick. From then on, the plant will absorb the water it needs via the wick. Just keep the reservoir filled with water (or a solution of water and fertilizer) at all times. This method is ideal if you are frequently absent, since wick-watered house plants can often go for weeks between waterings.

A capillary mat can also be used. This can be a commercially available capillary mat or a homemade one (old acrylic blankets or pieces of indoor/outdoor carpeting make great mats). Cut the mat to fit the saucer or, for a collection of house plants, use a large tray and set the plants directly on the matting. Water thoroughly from the top the first time, then simply keep the mat moist. The plants will be able to absorb water from the matting when they need it.

Keep reading to learn about humidity for house plants.

Want to learn about house plants by type? Try these:

Humidity for House Plants

Most plants need humid air in order to thrive. That’s because the pores through which they breathe lose most of their moisture when the surrounding air is dry, a loss that the plant can’t always replace through the water its roots absorb. The thinner the leaf, the greater its need for humidity. Thick, leathery, or waxy leaves, or those covered with hair, are usually relatively immune to dry air.

Symptoms of dry air include curled leaves and dry leaf tips, as well as a frequent need for watering. Flower buds are especially susceptible to dry air and may turn brown or simply fall off if humidity is too low.

Spraying house plants with water is a good way to increase humidity.

The humidity level in the average home is often below 30 percent, yet most house plants, even desert dwellers such as cacti, prefer humidity levels of at least 40 percent. Many require 60 percent or more. Relative humidity of 50 to 60 percent is probably ideal for both house plants and people.

Regional and Seasonal Variations

In some areas of the country, dry air is a chronic problem, especially in the arid Southwest. During periods of extreme heat, air conditioning has a further drying effect on the air. In such areas, the year-round use of a humidifier may be necessary.

In areas with cold winters, humidity levels drop indoors during the heating season. That’s because the relative humidity of cold outdoor air drops as it is warmed up. Certain heating systems, such as electric heat, compound the situation by further removing humidity from the air. In such cases, some sort of system to compensate for low humidity may be necessary during the winter months.

Air Circulation

Plants outdoors are exposed to air currents of all sorts, and many seem to need a certain amount of air movement indoors. Air circulation helps ventilate waste gases, remove excess heat, and prevent diseases that can develop in closed spaces. There is often adequate air circulation near large windows because of temperature differences between day and night, but elsewhere, especially under plant lights, it is wise to run a small fan to keep the air in constant movement. Don’t direct the fan on the plants. Just having it in the same room will provide the circulation needed.

Easy Ways to Increase Humidity

The best-known method of increasing air humidity is spraying houseplants with warm water. Unfortunately, this is not terribly efficient, since the humidity provided dissipates rapidly. To efficiently raise humidity by spraying, repeat the process several times a day.

A room humidifier will do wonders in increasing air humidity. Just make sure to fill it up regularly. Some modern homes have built-in humidifiers that can be adjusted to the desired level.

It is easy to build a plant humidifier of your own. Simply fill a waterproof tray with stones, gravel, or perlite and pour water over them so that the bottom ones rest in water while the upper ones are dry. Set the plants on one of these pebble trays. They will benefit from the added humidity given off as the water evaporates. By keeping the tray constantly half-filled with water, a nicely humid microclimate will be created.

For house plants with moderate humidity needs, grouping them together during the heating season is a simple solution. Each plant gives off humidity through transpiration. Clusters of plants will create very good humidity in the surrounding air.

Terrariums

Delicate, thin-leaved house plants require a humidity level of over 70 percent, a level that is hard to achieve in a large room. If this level is impossible to maintain, a terrarium, easily made from an old aquarium, can be the best solution. Fitted with a glass lid, it creates a microclimate in which humidity levels rise to almost 100 percent. Just open it slightly for ventilation if water droplets form.

In the next section, we'll talk about temperature for house plants.

Want to learn about house plants by type? Try these:

Temperature for House Plants

Almost all house plants come from tropical and subtropical climates with temperatures very much like those in our homes. A daytime temperature range of anywhere from 65Â° to 75Â°F (18Â° to 24Â°C) is just perfect for them, and most plants have no trouble tolerating occasional summertime highs of up to 90Â°F (32Â°C).

Generally speaking, indoor temperatures that you find acceptable will also be just fine for healthy growth of your house plants.

These geraniums grow well in the indoor temperatures of most homes.

Controlling Temperature for House Plants

Even tropical plants like cooler air at night than during the day. As a result, healthier growth will be seen if temperatures drop 5Â° to 10Â°F (3Â° to 5Â°C) at night. Night temperatures naturally drop indoors, especially near windows, but you can also turn the thermostat down at night to accentuate the change. Such cooler night temperatures are not only good for house plants and humans, they also help conserve energy.

Long periods of extreme heat can be harmful to house plants. You can increase ventilation through screened windows or a fan. Air conditioning will also help bring temperatures down to acceptable levels, but house plants should not be put directly in the path of cold drafts. Since humidity is removed from the air through air conditioning, some means of increasing humidity may be necessary, especially in dry climates.

Some Like It Cool

Subtropical plants, especially those forced into winter bloom in cool greenhouses, are not as tolerant of warm temperatures as most indoor plants. They can be placed near a cool window in winter or in a room that is only slightly heated. You can also make a mini-greenhouse by bending two clothes hangers into a half circle and attaching them to the window frame, then covering the hangers with a sheet of plastic. Temperatures inside the mini-greenhouse will often be up to 10Â°F (5Â°C) cooler than the surrounding air.

In the next section, we'll talk about fertilizing house plants.

Want to learn about house plants by type? Try these:

Fertilizing House Plants

Never try to equate fertilizing with feeding. Plants get their energy from light, not fertilizers. Unless good light levels are supplied and the plant is growing well, fertilizing will do more harm than good. Newly purchased or repotted house plants should be given a few months rest from feeding so that they can use up the nutrients already present in their growing mix.

Fertilizing is very important for plants growing in soilless potting mixes.

Plants require three major elements for healthy growth: nitrogen (N), phosphorus (P), and potassium (K). These are always listed on fertilizer labels in the form of ratios: 6-12-4, for example, indicates 6 percent nitrogen, 12 percent phosphorus, and 4 percent potassium. Most fertilizers also contain some of the minor elements -- magnesium, boron, iron, etc. -- that plants also need for growth.

Generally speaking, fertilizers rich in nitrogen (the first number) will stimulate healthy, green growth of foliage, while those rich in phosphorus (the second number) will encourage good root development and improved flowering. Those rich in potassium (the third number) will help build up reserves for plants that have a dormant period.

A fertilizer labeled 30-20-20 would be good for leaf development and would be most recommended for foliage house plants, while flowering house plants would prefer one richer in phosphorus, such as 15-30-15. Most foliage house plants get along fine with an all-purpose or high-nitrogen fertilizer, while one with a high proportion of phosphorus is best for flowering house plants.

Constant Feed

Most plants these days are grown in soilless potting mixes that offer very little in the way of nutrients, making regular fertilizing very important. One way to make sure your house plants get the fertilizer they need is to use a constant feed method.

Simply take a liquid or water-soluble fertilizer designed for a monthly application and reduce its dosage by four. For example, if the label states it should be applied once a month at a rate of one teaspoon per gallon, apply it at every watering at a rate of Â¼ teaspoon per gallon. Once a month, take the plant to the sink and leach it carefully by running clear water through its pot until the excess fertilizer runs into the drain. This helps prevent buildup.

Choosing Fertilizers for Your House Plants

Ready-to-use liquid fertilizers are convenient, but expensive, since you pay for the water they contain. Water-soluble fertilizers, available in powder or crystal forms, are just as efficient, but are more economical because you add the water yourself.

Some people prefer the practicality of slow-release fertilizers. These are available in granule form to be mixed with the soil or in spikes and tablets that are pushed into the potting mix. They need only be applied once every few months. The label on the fertilizer will suggest a recommended frequency.

Organic versus Chemical

Both organic and chemical fertilizers are available in a wide variety of concentrations. Since chemical fertilizers applied to house plants do not leach out into the outside environment, even growers who use only organic fertilizers outdoors often have no qualms about using chemical ones on their indoor plants.

One popular organic fertilizer is liquid seaweed. It is applied as a foliar spray and absorbed by the plant’s leaves.

Tools for House Plant Care

House plants do not require a shed full of expensive gardening equipment. In fact, most indoor gardeners find they can get along fine with simple kitchen utensils: a spoon for repotting, a pair of scissors for cutting off yellowing leaves, a sharp knife for taking cuttings, and a recycled window spray bottle for applying pesticides. The most important tool for proper plant care is a good watering can. Look for one with a long but narrow spout.

ÂIn the next section, we'll talk about potting house plants.

Want to learn about house plants by type? Try these:

Potting House Plants

Repot house plants at least once a year, preferably in the spring. Fast-growing house plants may require repotting two or more times a year.

One sign that a house plant needs repotting is when it begins to wilt only a few days after a thorough watering. House plants should also be repotted when they threaten to tip over (put these into clay pots or use a heavy potting mix). When a white or yellowish crust begins to build up on the plant’s stem and pot rim, indicating an excess of mineral salts, it is also time to repot.

Pots should have drainage holes so that excess water can drain out.

House plants that are difficult or impossible to repot -- a tree-sized plant, for example -- should be top-dressed annually. This simply means scraping off the top inch of potting mix and replacing it with new mix. This procedure will help remove any toxic mineral salts that have built up.

How to Repot

Tip the plant upside down, holding its stem and rootball firmly. If it does not slide out on its own, run a knife around the inside of the pot to loosen the rootball. With a pencil or your finger, remove up to one third of the original potting mixture from all around the rootball, gently teasing it loose. Trim off any dead or damaged roots. For repotting, choose a clean pot no more than one or two sizes larger than the previous one. If the plant has reached its full size, don’t increase the pot size. Pour enough potting mix into the bottom of the new pot to bring the plant up to its original height. Center it well and fill in the empty space with growing mix. A thorough watering will help the plant adjust to its new home.

Newly repotted house plants should be kept out of bright sun for a week or two.

Hydroculture

House plants don’t need soil for healthy growth: As long as their roots receive oxygen and moisture, they will thrive. In hydroculture, plants are grown in water using an inert medium such as clay pellets or pebbles as an anchor. A water level indicator tells exactly when to add water, often only once every few weeks. Nutrients are supplied in the form of slow-release pellets or tablets. Although rooted plants can be transferred to hydroculture by thoroughly rinsing their roots of all soil, it is usually easier to start plants from cuttings. Complete hydroculture kits are available for all sizes of plants.

The Right Pot for the Job

Plastic pots (and other containers made of nonporous material) dry out slowly and are ideal for house plants that like their soil kept evenly moist. House plants preferring drier soil will do better in clay pots, since these allow water to evaporate, reducing the danger of overwatering.

All pots should have drainage holes so excess water can be evacuated. Decorative pots without drainage holes can be used, but only as an outside container.

Potting Mixes for House Plants

Most house plants thrive in ready-made all-purpose potting mixes. Most modern mixes are soilless, made of peat moss, vermiculite, and perlite in various proportions. They are light and well aerated, yet hold moisture well, making them ideal for plant growth.

Asparagus ferns, caladiums, Boston ferns, and many other plants prefer this potting mix. Soil-based mixes are heavier and drain more rapidly. They make good choices for cacti and succulents.

Finally, certain indoor plants, such as cattleya orchids and Venus’s fly-traps, normally grow on trees in the wild and require very well-aerated mixes. They are often grown in fast-draining mixes such as sphagnum moss, bark chips, or special epiphyte mixes.

In the next section, we'll talk about temperature for house plants.

Want to learn about house plants by type? Try these:

Grooming House Plants

Simple grooming can mean the difference between an unattractive house plant and one that is really stunning, yet it is the most neglected aspect of basic plant care. Here are a few tips on how to turn your ugly duckling into a beautiful swan.

Removing dead leaves improves
a house plant's appearance.

The Quarter Turn

Plants naturally tend to grow toward the light and will soon begin to bend toward the nearest window, causing them to look lopsided or even to topple over. Prevent this by giving the plant a quarter turn each time you water it, so that the plant gets light from all sides. The result will be a symmetrical plant.

Keeping House Plants Clean

As plants grow, they produce new leaves and flowers and lose older ones. It is important to remove all dead and yellowing plant parts, not only to improve the plant’s appearance, but to prevent the proliferation of insects and diseases that often get their start there. A pair of scissors can be used to snip off dying leaves and flowers and to trim brown leaf tips to a natural-looking point.

To keep dust and grease from building up and slowing growth, clean leaves once or twice a year with a soft cloth dipped in soapy water or put them under the shower or outdoors during a warm rain.

A Pinch in Time

Don’t be afraid to prune out unattractive sections of the house plant. Generally, for every cut made, two new branches will be produced, making the plant look fuller than ever. Soft new growth can be pinched -- squeezed between the thumb and forefinger -- to promote branching without leaving a noticeable stub.

A Helping Hand

House plants that are properly pruned and receive a regular quarter turn rarely need staking. However, if an attractive stem has grown to the point where it no longer can support itself, use an unobtrusive stake, such as a section of bamboo, to prop it up. The result will look great.

Keep reading to learn about propagating house plants.

Want to learn about house plants by type? Try these:

Propagating House Plants

Most house plant enthusiasts enjoy the challenge of multiplying their plants, either to renew them or to have new plants to use as gifts. Not all the methods shown here apply to each house plant, but all can be propagated in one manner or another.

Stem Cuttings

Stem cuttings are the most popular method of plant propagation. The technique can be applied to all plants with noticeable stems. Select a healthy section of stem with at least three nodes (the bumps or rings where a leaf is or was attached) and cut it cleanly with a sharp knife just below the lowest node. Remove any flowers or flower buds as well as any leaves growing from the bottom node. A rooting hormone, available in the form of a powder, gel, or liquid, can be applied to the cut section. While not absolutely necessary, it can help stimulate faster rooting.

Stem cuttings are the most popular
method of plant propagation.

Cuttings can be rooted in water, but it is best to use a pasteurized rooting mix such as soilless growing media, vermiculite, sand, or perlite. Fill a pot or other container with mix and moisten it lightly.

Use a pencil to prepare a hole for the stem, then insert the cutting so that at least one node, and preferably two, are covered with mix. Firm the mix, then cover the container with a clear plastic bag to maintain high humidity, which is necessary to keep the young cutting from wilting.

Put the cutting in bright light, but not full sun, and supply warm temperatures. When the plant is well rooted and growing on its own (this can take from two weeks to several months), remove the plastic and treat the cutting like an adult plant.

Once the top section of stem cutting has been removed, the rest of the stem can be cut up into sections and also rooted. Just make sure not to invert stem cuttings. They must be right-side up in order to root.

Cuttings of succulents and cacti should be allowed to heal over before being potted, a process that can take anywhere from several days to more than a month. Don’t cover succulents with plastic since high humidity can cause them to rot.

Leaf Cuttings

Only a few plants can be reproduced by leaf cuttings, but their ease of propagation makes them very popular house plants, Break off a whole leaf, including its stalk, and insert the stalk into the rooting medium as above, covering the container with clear plastic. One or more new plantlets will soon sprout at the leaf’s base. They can be potted individually when they are well rooted.

In the case of a few plants (florist’s gloxinias, rex begonias, snake plants, and streptocarpus), even a small leaf section can be rooted. Cut a healthy leaf into sections, each one with a major vein, and place each section so its base is just barely covered with mix. New plantlets will soon appear.

Layering

This method applies mainly to plants with trailing stems or to those, like the spider plant, that produce baby plants on stolons. Simply set a pot filled with moist growing mix under a section of stem and pin it down to the mix with a hairpin or twist tie. When the attached section has rooted, cut it free from the mother plant and grow it on its own. Among the plants that can be propagated by this method are hare’s foot ferns, episcias, pothos, Boston ferns, and strawberry begonias.

Air Layering

The air layering method is used on trees or shrublike plants, often those with thick or woody stems that are hard to root from stem cuttings. Using a sharp knife, make a cut halfway through the main stem, about one third of the way down from the growing tip. Insert a sliver of wood or a match into the cutting to prevent it from healing over. Apply a small amount of rooting compound to the cut, then cover it with a handful of moist sphagnum moss. Wrap the moss in a sheet of plastic and attach the plastic to the stem with twist ties. Check the moss every week or so and add water if it dries out. When roots have formed, pot the new plant in an individual pot and treat it as an adult plant.

Division

Plants that grow in clumps are best propagated by division. Remove the plant from its pot and break the rootball up into sections, each with at least one rooted stem, using a knife if necessary. Plant the divisions in individual pots.

Certain plants produce offsets -- baby plants at the base of the mother plant. These can be cut free from the mother plant when they reach about one third of their size. At this point, most are well rooted and can be treated as any newly potted plant. If they are not rooted, treat them as cuttings.

Seed

Almost all house plants can be grown from seed, although seeds may be hard to come by. It is easiest to buy them from seed companies, but some plants will also produce seeds on their own.

Sprinkle the seeds over the surface of a moist growing medium and press lightly. Large seeds should be covered with a thin layer of potting mix. Cover the container with clear plastic or a sheet of glass and place it in a warm, brightly lit spot. When plantlets appear and have formed at least four true leaves, harden them off by gradually removing their protective covering, and pot them individually in small pots. Plants easily propagated by seed are asparagus ferns, begonias, primroses, and parlor palms.

In the next section, we'll talk about decorating with house plants.

Want to learn about house plants by type? Try these:

Decorating with House Plants

The real value of house plants lies in their use as decorations for the home. House plants automatically create a sense of coziness and put people at ease. Properly used, they can make large spaces look intimate and magnify small spaces to create an impression of depth. It is hard to imagine a decor that doesn’t call for at least a few house plants placed in just the right spots.

House plants can enhance
the decor of any home.

Movable House Plants

The spot in the home or office where a plant looks the best is not always the one in which it grows well, usually due to lack of light. Artificial lights could be installed to improve conditions, but it is far easier to consider house plants as movable objects. For every shady spot calling for greenery, buy two plants. While the first plant does duty as a decorative item, place the other in a brightly lit window, then, once a week, switch the plants around. You’ll keep your house plants healthy and attractive for a much longer time.

Flowering house plants need more light than foliage types and can rarely be grown anywhere but directly in front of a window. They can, however, be used as decorative items while in bloom and placed anywhere in the home. When they stop blooming, move them back into the light until they have recuperated enough to bloom again.

Dish Gardens and Terrariums

It is easy to make fascinating miniature gardens in small containers. Just mix small foliage plants and the occasional flowering plant in a decorative dish garden, or create one entirely composed of cacti and succulents.

A mixture of trailing and bushy plants, with the occasional upright one for contrast, will create an especially decorative effect. For delicate plants, use glass terrariums instead of trays. If the container is deep enough, don’t even unpot the plants -- just hide their pots in decorative mulch. Any plant that becomes unattractive can then be easily replaced without upsetting the other plants.

Keep reading to learn about preventing pests and diseases in house plants.

Want to learn about house plants by type? Try these:

Preventing Pests and Diseases in House Plants

The difficulties you might experience with your house plants could be caused by diseases, insects or cultural practices -- the care you give, or don't give, to your plants.

The following chart will help you identify plant symptoms that are caused by cultural practices, and show you how to treat them.

House Plant Cultural Problems

Symptom	Cause	Treatment
Pale growth with new leaves smaller than normal. The plant stretches toward the light.	Insufficient light	Move plants to brighter spot or closer to light source. Supply artificial light.
Foliage wilts, potting mix is dry.	Lack of water	Water thoroughly.
Foliage wilts, potting mix is moist. Soil smells of decaying vegetation.	Overwatering	Water less frequently. Increase light so plant can better absorb water.
Growth is slow and leaves are pale in color.	Lack of fertilizer	Apply appropriate fertilizer regularly throughout the growing season.
Growth is stunted, leaves are yellowed. A crustlike accumulation appears at the base of the plant's stem and on pot rim.	Buildup of mineral salts in the soil	In light cases, leach the soil thoroughly with clear water. In more severe cases, repot into fresh soil.
Plant does not bloom.	Various causes (too little light, too much water, etc.)	Improve growing conditions according to specific needs for each plant.

If pests are affecting your house plants, there is an increasingly wide range of biological pesticides, such as insecticidal soap, which can be used around the home without harming its other inhabitants.

It is important to use only appropriate pesticides in treating pests and diseases. Read the label carefully to make sure a pesticide is not only suited for the problem you wish to treat, but also to ensure that the product is not harmful to the plant you are treating. Always wear a mask, gloves, and long-sleeved clothing when working with chemical pesticides.

Organic pesticides are the preferred choice in an indoor environment. There are many very efficient organic insecticides and miticides -- insecticidal soap, diatomaceous earth, rubbing alcohol, rotenone, pyrethrine, etc. -- and powdered sulfur is a good organic fungicide.

The following chart will help you identify and treat plant conditions caused by pests.

House Plant Insects and Other Pests

Symptom	Cause	Treatment
Leaves take on a mottled appearance and appear dusty underneath. If the leaves are shaken over a sheet of white paper, tiny moving "spiders" are seen. In severe cases, a spidery webbing stretches between leaves.	Spider mites	Clean plant thoroughly with soapy water. Spray with insecticidal soap. Keep the air humid to prevent a recurrence.
Little balls of "cotton" (actually slow-moving insects or their egg cases) are seen on stems, at leaf axils, or on the plant's root system. Leaves yellow and may become covered with secretions.	Mealybugs	Touch individual insects and egg cases with a cotton swab dipped in rubbing alcohol. Spray the entire plant with a solution composed of 7 parts water and 1 part rubbing alcohol.
Shell- or scalelike bumps are seen on leaves and stems. Plants may yellow or become covered with secretions.	Scale insects	Scrape off the shells with an old toothbrush dipped in soapy water. Treat with insecticidal soap.
Green to black, round-bodied, translucent insects cluster together on new growth. Plants may yellow or become covered with secretions.	Aphids	Wash the plant thoroughly with a damp cloth dipped in soapy water. Treat with insecticidal soap.
Tiny, white, dandrufflike insects rise up when the plant is touched. Small translucent bumps are seen underneath the leaves.	Whiteflies	Use a vacuum to suck up flying adults, then wash the plant thoroughly with a damp cloth dipped in soapy water. Treat with insecticidal soap.
Leaves and foliage are streaked and mottled. Hyphen-sized insects scatter about when the plant is breathed upon. Tiny black excrements are found on infected plant parts.	Thrips	Remove severely infested flowers and foliage. Treat with insecticidal soap.
New growth is distorted and turns brown and dry, eventually ceasing altogether. This problem is very host-specific, affecting mostly African violets, begonias, and cyclamens.	Cyclamen mites	This problem is very difficult to treat. It is often best to get rid of infected plants. An appropriate miticide or repeated insecticidal soap treatments can be used if the plant has great value.
Tiny insects are seen jumping on the soil surface during watering.	Springtails	Springtails are basically harmless. Letting the soil dry out between waterings will discourage them.
Tiny black midges are seen hovering around plants and elsewhere in the house. Grublike larvae are seen in the soil.	Fungus gnats and sand flies	These insects are annoying but relatively harmless to indoor plants. Letting the soil dry out between waterings will discourage them.

Plant conditions could also be caused by diseases. The following chart will help you identify your house plant's symptoms and learn how to treat them.

House Plant Diseases

Symptom	Cause	Treatment
White mold appears on leaves and flowers. Plant parts may yellow and die.	Mildew	Improve air circulation. Don't moisten foliage when watering. Treat with an appropriate fungicide.
Gray, fluffy mold appears on leaves, flowers. Plant parts may yellow and die.	Gray mold (botrytis)	Improve air circulation. Don't moisten foliage when watering. Treat with an appropriate fungicide.
Yellow, brown, or black spots appear on leaf surfaces and may spread until the entire leaf dies.	Leaf spot	Can be caused by various disease organisms. Improve the air circulation around the plant. Don't moisten foliage when watering. Treat with an appropriate fungicide.
Black patches appear at base of stem or underground on the roots. The plant wilts and doesn't recover even when watered. A smell of decaying vegetation may be noticeable.	Root or stem rot	Can be caused by various disease organisms, but is usually linked to overwatering. Start the plant over from cuttings.

The vast majority of insect and disease problems can be avoided by using only pasteurized potting mixes and carefully isolating new plants after purchase.

In the final section, we'll talk about vacation care for house plants.

Want to learn about house plants by type? Try these:

Vacation Care for House Plants

Plants are living beings and prefer regular care, but frequent or lengthy absences need not stop you from filling your home with greenery. Some house plants, such as cacti and succulents, can literally go for months without water and should be perfect for even frequent travelers. By using watering systems such as wicks, capillary matting, and hydroculture, you can keep most plants happy for two weeks or even more. The plants that need the least care are those grown in sealed terrariums. They can often go for years without water!

Flood house plants with water and place them on
a water-filled tray before leaving on a long trip.

Leaving House Plants at Home

If you suddenly find yourself facing a prolonged absence and your house plants aren’t able to survive on their own, there is no need to panic. There are a few last-minute tricks you can try to keep even difficult house plants living during long periods without regular care.

Start by setting them in a shady spot and removing any flowers and buds to reduce the amount of water they need. Although plants normally don’t like waterlogged soil, they can put up with it occasionally, so set them in a deep tray and literally flood them with water. After this treatment, most plants can go for at least three weeks on their own.

Fragile plants can be covered in plastic when you are away from home for a long time. Since no water is lost to evaporation, plants can go for over a month without care.

Finally, you can simply leave your plants in the care of a horticulturally experienced neighbor. Have your neighbor come in once or twice a week and water as needed.

Want to learn about house plants by type? Try these:

ABOUT THE AUTHOR:

Larry Hodgson is a full time garden writer working out of Quebec City in the heart of French Canada where he grows well over 3,000 species and varieties. His book credits include Making the Most of Shade, The Garden Lovers Guide to Canada, Perennials for Every Purpose, Annuals for Every Purpose, Houseplants for Dummies, and Ortho’s Complete Guide to Houseplants, as well as other titles in English and French. He’s the winner of the Perennial Plant Association’s 2006 Garden Media Award.