Gardening with Indoor Plants

Growing indoor plants is an enjoyable hobby for millions of people around the world. My current indoor plant collection consist of three Kaua'i White Sugarloaf pineapples, one Extra Sweet Gold pineapple, two Queen Victoria pineapples, one Natal pineapple, one Cayenne Hilo pineapple, one Spanish Samoa pineapple, one bilbergia nutans, and one Calamondin orange.

Growing plants successfully starts with selecting the right plant for the right indoor environment. You should also keep in mind that the closer you come to matching the plant's native habitat, the better off your plant will be.

Light

Light is possibly the most important factor that determines where a plant should be displayed inside your home. Since light provides the energy necessary for a plant to manufacture food, the spot you choose will directly impact its performance. When a plant receives light, there are three important factors that come into play - intensity, quality, and duration.

All plants require a certain light intensity to grow and thrive. Indoor plants are often grouped together by the amount of light required for good growth. Light intensity is measured in footcandles by a light meter. Plants that require high light ( + 500 f.c.) will thrive in south-facing windows. Plants that require medium light (200-500 f.c.) will thrive in filtered sunlight, and plants that require low light (80-200 f.c.) will thrive in bright indirect light or a north-facing window.

Light quality is concerned with the light source. Does your plant require direct sun, filtered sun, bright indirect sun, or artificial light to grow well indoors? Direct sun is the most intense light available. Filtered bright sun is light diffused by window blinds or sheer curtains. Bright indirect sun is reflected light from a lightly-colored object such as a white wall. Artificial light from fluorescent or HID lamps offer the best supplemental or sole light source indoors.

Duration is the length of time a plant receives light. Duration can influence a plant's growth, flowering, and fruiting cycle. Since most indoor plants are tropical in origin, they require many hours of light to grow well. Some plants require a certain amount of daylength to flower or fruit. This phenomenon is known as photoperiodism. Plants that require the daylength to be less than 12 hours are called short day plants. Plants that require the daylength to be more than 12 hours are called long day plants. Plants that are not influenced by daylength are called day neutral plants.

Environmental Change

When you move your plants outdoors in the summer or indoors in the winter, the transition must be gradual to avoid any shock. For outdoor preparation, choose an area that receives only weak morning or evening sun. A shade structure made from wood or shading cloth is ideal for adapting plants. For indoor preparation, gradually decrease light levels over a 3 week period by moving plants to a shadier area or by using different shading fabrics.

Artificial Lighting

There are many lighting systems available on the market today. Generally speaking, there are two main lighting systems used by indoor gardeners: fluorescent and high intensity discharge.

Fluorescent

Fluorescent lamps have really advanced over the years. The traditional 4 foot T12 lamps are excellent for raising seedlings and growing small plants with low light requirements. The high output fluorescents, T5 and T8, can produce enough light to grow plants with medium to high light requirements.

High Intensity Discharge

High intensity discharge lighting is one of the best artificial lighting systems an indoor gardener can purchase. It can be used to grow a very wide range of plants including vegetables, herbs, fruiting tropical plants, and flowers.

HID lamps are used commercially to illuminate streets, industrial factories, stadiums, parks, and parking lots. Commercial greenhouse growers have been using these lights for years as a supplement to natural light. Well-designed home units are available from many hydroponic and indoor gardening supply companies. There are two types of HID lamps available for use: high pressure sodium and metal halide.

High Pressure Sodium

HPS lamps emit a yellow-orange light similar to the natural hue of a rising or setting sun. These lamps are best used as a supplement to sunlight. If you have a greenhouse or sunroom, use HPS lamps.

Metal Halide

Metal Halide lamps emit a blue-white light. These lamps are best used if you grow your plants in an area that receives little or no sunlight. Plants generally grow well under halide light.

Check out my online garden suppliers listing for companies that sell HID lighting and fluorescent units.

Humidity

Humidity is the amount of water vapor present in the air. The instrument that is used to measure humidity is called a hygrometer. It can be found at your local hardware store where the thermometers are located. Every indoor gardener should have one!

During the heating season, indoor air lacks adequate moisture. Dry, warm air puts a lot of stress on plants making them more vulnerable to disease and insects. The ideal indoor humidity range should be 45% to 50%. Using a room humidifier is the best way to add moisture for your plants and yourself. There are several types on the market for home use.

Steam Humidifiers
These units work by heating water in a small chamber with two electrodes. The water boils and steam exits through a small opening. Hot steam will burn. Keep unit away from small children and pets.

Cool Mist Humidifiers
These units work by breaking up water into a fine mist. This is done by using either a transducer or a rotating agitator.

Evaporative Humidifiers
These units work by using a fan to force air through a constantly wet porous wick.

NOTE: All humidifiers should be cleaned at least once a week with a cleaning solution that destroys mold, mildew, and bacteria. A dirty humidifier can breed mold spores and bacteria.

Temperature

Most indoor plants are native to the tropical and subtropical regions of the world. They enjoy temperatures between 70°F and 80°F (21°C and 26°C) during the day and 60°F to 65°F (13°C to 16°C) at night. This temperature range can be duplicated somewhat by lowering your thermostat at night.

Some plants are sensitive to cold water like gardenias and African Violets. To avoid any potential shock, always use room temperature water.

Avoid warm drafts which can dry out plant foliage. Avoid cold drafts which can cause chilling injury. Avoid sudden temperature changes which can cause leaves to drop.

Watering

Knowing when to water your plants can be tricky. There are many factors that influence water loss such as the amount of leaf surface a plant possesses, soil type, container size or type (clay or plastic), temperature, and humidity. Certain plants like the soil to be kept evenly moist, while others like the soil to be kept drier. Incorrect watering can lead to all sorts of problems like leaf drop, wilting, and root rot. Before watering your plants, dig down an inch or more to feel the soil. If the soil is still moist, don't water.

After watering your plants thoroughly, always empty the water in the drainage saucer. Failure to do so will cause oversaturated, airless soil. This condition can lead to root rot. A sure sign of root rot is foul smelling drainage water.

There are some soil moisture meters on the market today that monitor the soil moisture level and indicate when watering is needed. These devices are not a 100% foolproof.

Water Quality

Tap water, for the most part, can be used to water plants. In some parts of the U.S., the pH of tap water is alkaline (above 7) due to the calcium and magnesium mineral salts. Many indoor plants like acidic soil. To lower the pH, add a tablespoon of white vinegar to a gallon of water. Chlorinated tap water can be set aside in an open bottle or container for a day or two. This will allow the chlorine gas can escape.

If you have a softener connected to your home water system, don't use the tap water to irrigate your indoor plants. The sodium in the water can do harm to your plants.

Potting Soil

There are many brands of potting soil on the market today. In general, indoor plants grow well in potting soils that are loose, well-drained, and moisture retentive.

Most commercial growers use artificial soil mixes because they're sterile and lightweight. A typical soilless mix may contain one or more the following ingredients: sphagnum peat moss, vermiculite, perlite, shredded bark, leaf mold, compost, coarse sand, or other materials.

Since most artificial soils contain little or no essential elements or beneficial soil microorganisms, it's a good idea to incorporate one fourth of your potting mix with leaf mold, worm castings, or humus. For established plants, add a layer on top.

Fertilization

Since plants manufacture their own food by photosynthesis, fertilizers are only needed to supply the essential elements needed for the process. Fertilizers come in many forms: powdered, liquid, granular, slow-release spikes, tablets, and capsules. All forms can be used on indoor plants. Read the label for the recommended rate.

One key thing to look for when purchasing fertilizer is the ratio of nitrogen, phosphorus, and potassium. Nitrogen promotes leaf growth. Phosphorus promotes flowering, fruit production, and strong healthy roots. Potassium strengthens overall plant structure. A 1:1:1 ratio fertilizer, like 10-10-10, is good for most indoor plants. However, if you are growing flowering and fruiting plants indoors, a different ratio maybe needed.

How and When to Fertilize

How and when to fertilize your indoor plant will depend on what type of plant you have, the stage of growth it is in, the temperature, and the light intensity. In general, more fertilizer is needed when the plant is actively growing and less is required during the winter season.

Pest Control Strategy

The best way to control pest problems is through prevention. When you buy plants always inspect the leaves and stems carefully. All newly acquired plants brought into the home or greenhouse should be isolated from other plants for two or three months. Monitor isolated plants weekly for pest infestation.

Every indoor gardener should have the following materials on hand ready to combat any pest that dares to show up on your plants.

Magnifying glass
Artist's paintbrush
Q-tips
Rubbing alcohol
Mild liquid soap
Sprayer
Latex or Vinyl gloves

Inspect your plants frequently. Use a magnifying glass and check the leaves and stems. For light infestations, use a strong spray of mild soapy water to wash foliage, spot treat areas with a cotton swab and alcohol, or remove pest by hand.

What's Attacking My Plant?

Before you spray any plant for an insect problem, it is good to know what type of insect is causing the problem. There are several insects and mites that feed upon indoor plants. The main culprits are spider mites, aphids, mealybugs, scale insects, and whiteflies.

Spider mites are very small, so a magnifying glass is needed to view them. Another way to identify them is to look for a fine network of webs on the leaves. They feed on the leaf sap eventually causing the leaf to yellow. High humidity discourages them.

Aphids are approximately 1/16 to 1/8 of an inch long. They live in colonies, breed fast, and feed upon young shoot tips and flower buds by removing the sap.

Mealybugs are tiny, white insects that look like dots of cotton. They are often seen in leaf axils, underneath leaves, and stems. These insects feed by removing the plant's sap.

Scale insects have a tan, crusty shell covering. They appear as brown bumps on leaves and stems. They feed on the leaves removing the sap. Adults are harder to control than the young.

Whiteflies are tiny, white, flying insects that feed on the plant's leaves by removing the sap. The young, non-flying insects also feed on the leaves. These insects are attracted to yellow objects. Use sticky yellow traps to catch flying adults or suck them up with a vacuum cleaner.

Non-Chemical Spray Control

For heavily infested plants, it may be necessary to use an insecticide or miticide for eradication. There are many environmentally-safe products available on the market: insecticidal soap, horticultural oil spray, hot pepper wax spray, pyrethrin, and neem extract. Read the label before using any insecticide or miticide.

Insecticidal soap is composed of fatty acids which will penetrate soft-bodied insects and interfere with their metabolism. Soap only works on contact. Good for aphids and spider mites.

Horticultural oil spray is a light oil/water mix in which a surfactant is used to help keep the mixture together. It is applied by a pressure sprayer. It works by suffocating the eggs and pests. Plant coverage must be thorough to work effectively. Good for mealybugs, scale insects, aphids, and spider mites.

Hot pepper waxis made from cayenne peppers. The cayenne extract works as a strong repellent and the wax coats and smothers insects and their eggs. Good for aphids, spider mites and whiteflies.

Pyrethrin is a botanical insecticide derived from pyrethrum daisy flowers. It works by paralyzing pests. Good for aphids, spider mites, and whiteflies.

Neem extract is a botanical insecticide derived from the seed oil of the neem tree (Azadirachta indica). It works as a repellent, antifeedant, and growth inhibitor for insects. Neem controls a broad range of insect pests.

Disease Control

Diseases often show up on indoor plants due to incorrect cultural practices. Root rot and crown rot result from overwatering. Gray mold and leaf spot show up on leaves when they remain wet too long from misting because air circulation is poor.

There are many plants suitable for indoor culture. The chart below list some of the most popular and easily grown plants. Plants are characterized by their common name, botanical name, required light intensity, and growing temperature.

Indoor Plant Chart

The chart below list some of the common problems encountered with growing tropical plants indoors. Most problems tend to occur during the heating season.

Troubleshooting Indoor Plants