Most of us continue to spend more time indoors while outside temperatures are uncomfortable. Let’s revisit some basic principles for growing houseplants and perhaps discover some lesser-known indoor plant facts.
Light, water, temperature, fertilization, and soil are chief factors affecting indoor plant growth. Light is the energy source to photosynthesize and produce food. Excessive light is as harmful as too little light. If your plant leaves are pale or turning brown, they are getting too much direct light. The quality of light, or wavelength, is an important aspect for growth. Two colors that plants use most effectively are blue and red. Household incandescent lights emit mainly yellow light, which is of little use to plants—surprise to me! Fluorescent lights are more effective. But north-facing windows should produce healthy foliage plants, and some flowering plants may prefer other sunnier windows.
Too much water or too little water accounts for many indoor plant losses. Roots are usually in the bottom two-thirds of the pot, so wait until the bottom two-thirds start to dry out. You must feel the soil. Stick your index finger about two inches into the soil. If it feels damp, don’t water it. You can also use a store-purchased moisture meter to eliminate dirty fingers. Plants prefer room-temperature water and not a steady diet of water run through a softener—another surprise to me! The best air temperature for indoor plants is between 70 and 80 degrees Fahrenheit during the day and a bit cooler at night.
Regarding containers: Unglazed, porous clay pots are considered the healthiest type for a plant because they provide excellent aeration for plant roots. Plastic or fiberglass pots are okay to use and need less frequent watering. A good potting soil should be dense to support growth, porous for drainage, have adequate nutrients, and be weed seed-free. Most commercially prepared mixes contain no soil. Organic and non-organic (perlite, etc.) materials are used. Like most plants, indoor pots need a balanced fertilizer that has food elements nitrogen (N), phosphorus (P), and potassium (K). A common formulation is 20-20-20 or 8-7-6. Most plants grow best when half the recommended strength is used, and only fertilize when the soil is moist. For most houseplants, fertilizing once a month in spring through early fall is adequate.
I hope you find this information helpful in caring for your prized indoor plants. Happy gardening!