The beauty of a garden does not need to be limited to the outdoors. You can bring the color and vibrancy of plants indoors too. There are many types of houseplants that will thrive indoors all year round! They are wonderful in the winter months for those of us that love to get our hands in the dirt. All you need to do is follow a few simple steps to keep your houseplants healthy and looking their best.
Caring for Houseplants
Houseplants are probably killed or injured more often by improper watering than by any other single factor. No general schedule can be used for watering all houseplants. Size of plant, pot, light, temperature, humidity and other conditions influence the speed with which the soil mass dries out.
When to water
In general, flowering plants need more water than foliage plants of the same size. Never water any plant unless it needs it. Soil kept either too wet or too dry causes plant roots to die, which leads to poor growth or death of the plant. Never allow plants to wilt, and never allow them to stand in water for long periods of time.
Learn to gauge the moisture content of the soil by its color and feel. As the soil surface dries, it becomes lighter. Under continued drying, the soil begins to crack and pull away from the sides of the pot. When severe drying occurs, some damage already will have been done to the roots. Soil kept too moist becomes sticky and slimy, thus inviting root rots and other disease problems. The general rule when watering is to check the soil by placing your finger or thumb below the soil surface. Sometimes it can be tricky to tell if the plant needs water just be assessing the surface. If you find that the soil is dry after placing your finger below the surface, then you know you need to water! If it is sticky or moist, you do not want to add water to your plant. If you want to take the guess work out of watering, you can purchase a moisture meter that will tell you if the plant is wet or dry. You can find these at the garden center, please ask if you need assistance.
How to water
Plants may be watered from either the top or the bottom of the pot. If you prefer watering from the top, use a watering can with a small spout and keep as much water off the foliage as possible. Each time, wet the entire soil mass, not just the top inch. Add water until it comes through the drainage hole in the bottom of the pot. Discard water that remains beneath the pot one hour after watering.
Watering from the bottom ensures thorough wetting of the soil mass. Place the pot in a pan or saucer filled with water, or dunk the pot to just below its rim in a deep bucket of water. When the top of the soil becomes moist, the entire soil ball should be wet. Remove the pot, allow it to drain, and return it to the saucer.
Salts may form a white accumulation on the soil surface if plants are watered regularly from the bottom. Occasional watering from the top helps wash out the salts. Don’t allow the soil to reabsorb any water that has been run through the soil to leach out salts. If surface salt accumulation becomes too heavy to remove in this way, scrape off the surface soil and replace it with fresh soil. Try not to injure plant roots.
Potted plants should always have good drainage. Occasionally, the drainage hole may become clogged by roots. Check it by pushing a finger, stick or pencil into it. Even if drainage from the pot is good, pot coverings can hold water. Pots wrapped in waterproof foil or placed in deep planters should be checked occasionally for standing water.
Plants with “wet feet” soon look sick — leaves yellow or drop, flowers collapse, and normally healthy white roots turn brown. Any or all of these symptoms can result from stagnation of the water, too little soil oxygen and development of diseases that rot the roots.
Improper light intensity ranks close to improper watering as a frequent cause for failure with houseplants. A plant in proper light is better able to withstand the high temperature and low humidity of many homes. The amount of light necessary for good growth varies with different types of plants (Figure 1).Figure 1
Chinese evergreen is one of many foliage plants adapted to conditions in the home.
All flowering plants need moderately bright light. Plants kept continuously in poor light will have spindly shoots, few flowers, yellow foliage, poor flower color and, often, little or no growth.
South, east or west windows are excellent for most flowering potted plants, with the possible exception of African violets and related plants, which prefer a north window.
Light in the average room, away from windows, is not bright enough for most flowering plants, even when ceiling fixtures are kept on.
Foliage plants are generally divided into those suitable for low-light areas, moderate-light areas and bright-light areas. Only a few plants can tolerate dimly lit room interiors. Most foliage plants do well with light at a north window, daylight with no direct sun, or sunlight diffused through a lightweight curtain. Plants that require full sunlight should be put in a south window.
Plants can become acclimated to a location. An abrupt move from a low-light to a bright-light location may be damaging. Leaves gradually face toward light for maximum light absorption, especially in low-light areas. Moving a plant disrupts this orientation and causes the plant to use light less efficiently for a period of time. This is especially true of large plants.
Abruptly moving a plant to more intense light — especially direct sunlight — results in bleaching or burning of foliage. Any lighting changes should be made gradually. Many plants can be kept from getting one-sided by turning them once a week.
Proper temperatures for plants are often hard to find in the house. A hot, dry atmosphere shortens the life of flowers. Flowering potted plants do best in temperatures of 65 to 75 degrees F during the day and 55 to 60 degrees F at night. To extend the bloom of flowering potted plants in the home, move them to a cool spot at night.
Foliage plants are more tolerant of high temperatures, but they thrive at temperatures between 65 and 70 degrees F.
In winter, the temperature near windows may be cooler than elsewhere in the house. If drapes are drawn around a plant placed near a window, the temperature may be too cool. On cold nights, check temperatures close to windows. Some tropical foliage plants can be injured by temperatures below 40 degrees F.
Do not put plants at windows that have hot air registers or radiators directly below them. Hot air blowing on a plant often causes leaves to brown on the edges and, occasionally, to drop or die.
Air in most modern homes is extremely dry during the winter. A furnace or room humidifier can help plant growth. If a humidifier cannot be used, watertight trays placed beneath the plants and filled with constantly moist sand or gravel help increase humidity around the plants. Pots must be placed on, not in, the wet sand or gravel.
Misting over the leaves daily can help a plant overcome the stress of low humidity. Plants needing constant high humidity, such as orchids or gardenias, are best kept in kitchens or bathrooms, where humidity often runs higher. A relative humidity between 40 and 60 percent is best for most plants but is difficult to attain indoors.
Newly purchased plants have been well fertilized in the greenhouse. They seldom need additional fertilizer for a few weeks. Plants that will be discarded after flowering will not benefit from being fertilized. Plants that will be kept should be put on a regular fertilization program.
When to fertilize
Fertilizing once a month is adequate for most houseplants that are producing new growth or flowers. However, plants do not need fertilizer in winter when no new growth is apparent.
Do not use fertilizer to stimulate new growth on a plant located in poor growing conditions. Lack of growth is more often due to improper light or watering than to nutritional deficiencies. In such cases, adding fertilizer may actually cause additional injury.
Drop of lower leaves, overall yellow-green color or weak growth may indicate a need for fertilization. However, these same symptoms may result from poor light or overwatering, so evaluate all conditions before fertilizing more than normal. If you aren’t sure, and can safely bring your plant to the garden center, a member of our staff can assist you with a diagnosis.
Kinds of fertilizers
Water-soluble, complete fertilizers formulated for houseplants are available at the garden center. They are easy to use. Formulations vary, so be sure to follow directions carefully. Do not apply more than directed. The roots of potted plants are quite restricted and easily burned by the application of too much fertilizer at one time.
Never apply liquid fertilizers to a wilted plant. Water the plant first, and apply fertilizer after the plant has recovered and the soil has dried slightly.
Some people prefer to use organic fertilizers for houseplants, but either an organic or inorganic fertilizer will be a satisfactory source of nutrients.
Fertilizers that release nutrients slowly or over a long time period require less frequent application than liquid forms. They are available in beads, pills, spikes and other forms. Never exceed amounts suggested by the manufacturer’s directions.
Plants just brought home from the greenhouse seldom need immediate repotting. Many will not require potting for some time. A newly acquired plant must make adjustments to its new environment, and repotting immediately puts added strain on the plant.
A time for repotting is when the plant becomes pot-bound, this is when the plant’s roots are too extensive for its pot. A pot-bound plant may need to be watered too frequently and may grow poorly. You can generally tell if a plant is pot bound when you can see the roots poking out through the bottom of its container. This is the time to re-pot your plant!
We feel that Espoma makes a good potting mixture for most houseplants. It is an organic mixture that is a customer favorite! Choose a pot that is only one size larger than its current one. If you make a drastic change by choosing a much larger pot, you risk the soil remaining too wet causing damage to the roots of the plant.
When repotting, avoid excessive damage to the root system. Firm the soil gently around the root ball, but do not press so hard that the soil becomes compacted.
Allow enough space at the top of the pot so that water can be added easily. Water newly potted plants thoroughly, drain, and do not water again until necessary.
*We do offer repotting services if you would prefer a professional to repot it for you. Call us for details. (412) 241-0411
Insects and diseases
Watch new plants carefully for development of insect or disease problems. If detected early, these problems often can be corrected easily before serious damage is done. If undetected or ignored, they may become difficult to control. The three most common and difficult houseplant pests are spider mites, scales and mealy bugs.Figure 2
Brown leaf tips is a typical symptom of fluoride toxicity, a common problem in Peace Lilies . This happens when the water contains too much fluoride for your tender plants. To rid this problem simply leave the water in your watering can overnight. The fluoride will leave the water and can then be used to give your plants a drink. When you take water directly from the tap, this can cause the tips to turn brown. Figure 3
Plants can suffer chill injury when their leaf temperature fluctuates suddenly. Keep such plants away from cold drafts and use water that is room temperature when watering. Other plants turn black when they get cold. Be sure to keep them from drafty areas and away from cold windows during the winter months. Figure 4
Some interior plants such as Dieffenbachia contain calcium oxalate, which is a known toxin. Take special precautions when using these plants in homes with children.
*If you are having issues with a particular insect, or you wish to have an insect identified, please bring us a sample of the plant and if possible, the insect that is causing the damage. We will help you find a solution!
During the summer, many houseplants can be revitalized if placed outdoors. Do not rush the plants outside too early in the spring. Late May is usually soon enough. Cool nights may injure some plants.
First, place the plants in a sheltered spot on a porch, beneath a tree or behind shrubs close to the house on a mild day, preferably when the weather is cloudy. After about one week of this adjustment, they may be moved to a more exposed but sheltered spot for the rest of the summer.
Plants with large leaves should be placed where they are protected from the wind because their leaves are easily torn.
Potted plants dry rapidly outdoors. Submerging the pots in soil can reduce watering frequency, as well as keep the pots from falling over. Lift each pot occasionally to keep roots from growing out of its drainage hole and to prevent the plant from becoming established outdoors. Fertilize monthly, and check occasionally for insects or diseases that may attack the plants outdoors. Move plants indoors by mid-September before cool weather returns.
Bringing Houseplants Indoors for Winter
There is one important step that we recommend before bringing your houseplants and tropicals indoors for the winter. It is quite common that your plants can develop insects that live inside the soil. Once indoors, these pesky bugs can infest ALL of your plants and reek havoc for you in your home. We recommend that you treat your soil with Bonide Systemic Granules for houseplants. You can also spray the foliage with Insecticidal Soap before moving them inside. This preventative step can truly save the life of your plants.
Although all houseplants grow best with good care, a few tolerate abuse better than others. Some of the most durable houseplants are:
- Snake plant (Sansevieria trifaciata)
- Heart-leaf philodendron (Philodendron scandens)
- Golden pothos (Epipremnum aureum)
- Corn plant (Dracaena fragrans)
- Janet Craig dracaena (Dracaena deremensis)
- Baby rubber plant (Peperomia obtusifolia)
- Cast iron plant (Aspidistra elatior)
- Parlor palm (Chamaedorea elegans)
- Chinese evergreen (Aglaonema modestum)
- Spider plant (Chlorophytum comosum)