The obvious value of houseplants is their use as decorations, but they also create coziness. There are scientific studies showing that living plants make people feel calmer, satisfied and more efficient.
Tending plants is therapeutic and relaxing. If that is not enough reason to grow live plants, consider that they also filter pollutants from the air of your closed-in house. Those of us in the northern states appreciate them even more, because there is not much outside color for several months each year.
Light is critical
The most important criterion in growing plants is light, because they absorb it to convert energy into sugars and starches. If there is not enough light, plants become pale, weak, stretch and do not flower. Simply increasing water and fertilizer does not help, and probably will cause the plant to rot.
Light varies according to the season. The total sunlight time in the dead of winter is as short as eight hours. In summer, it is more than 16 hours. The angle of the sun in summer may make the southern exposure too intense for houseplants. A northern exposure will not give enough light in winter, but may be good for some plants in summer.
A south facing window will have full sun from late morning to mid afternoon. Cacti, succulents and flowering plants do well here and can be set fairly far back. The best exposure is from the east, as it has full sun for a short time in the morning and it is brightly lit for the rest of the day. It is cooler than a west window and is good for foliage and flowering plants.
West windows allow full sun for part of the day and bright sun for the rest, but it may be too hot for some foliage and flowers. A north exposure may be bright enough for foliage plants in summer, but the plants must be close to the glass. In all cases, the size of the window makes a big difference for light availability.
There are some ways to modify the light. Use a sheer on the window or move the plants farther away from the window to lessen the heat and intensity of the light. You may prune some of the shrubbery outside the window to allow in more light. The simplest solution, however, is to keep the window clean.
Artificial lights are an answer for some areas, but need to be kept on for 12 hours to 14 hours a day. Fluorescent and halogen have the right spectrum and are good; incandescent lights give out too much heat and are poor.
Right way to water
Most houseplants prefer even moisture, although there are some that like to dry out between watering. Check the soil every two or three days by poking your finger down about an inch and water if it is dry at that level. With smaller containers, you can tell they are dry by their lightness in weight. A hollow sound when you tap on the pot also indicates dryness.
Water thoroughly and then wait before you water again. Water until it drips out the bottom of the pot, and then discard the water that has accumulated in the saucer.
Plants may never recover from severe wilt, but if they become too dry try soaking the whole pot in a pail of water. Drain well after the root ball is saturated.
You may wish to water from the bottom of some plants. Fill the saucer, wait 20 minutes and then pour out the excess. Water from the top once a month to leach out excess minerals.
Temperature and humidity
Most houseplants are tropical or subtropical so they like the same temperatures we do and little cooler at night is good. However, the humidity in most homes is less than 30 percent and plants want at least 40 percent. For people and plants, 50 percent to 60 percent humidity is ideal.
Both heating and air conditioning removes moisture from the air. The thinner the leaf, the more humidity that is required as their pores easily dry out. Thick, wavy, leathery or hairy leaves are not bothered by dry air. You can add extra moisture with a humidifier, or mist your plants two or three times a day. Group the plants together to take advantage of transpiration, or place them on a pebble tray filled half way up with water.
Fertilizer and grooming
New plants and those that have just been repotted do not need fertilizer for a few months when they have used up the soil nutrients. Fertilize monthly during the active growing season. You may opt to constantly feed them by using 1/4 of the monthly rate of water-soluble granules each time you water.
Another method is to mix slow-release fertilizer granules in the potting mix. Fertilizers have nitrogen (N) for green growth, phosphorus (P) for root growth and potassium (K) for reserves in the dormant periods. Fertilizers high in phosphorus are best for flowering plants.
Keep your plants looking neat and healthy with regular grooming. Give them a quarter turn each time you water. Prune off unattractive sections and you will generally be rewarded with two new branches per cut.
Pinch off soft new growth to make the plant bush out. Remove dead and yellowing leaves and trim off brown leaf tips.
Clean the foliage with a soft cloth dipped in soapy water, or put your plants in the shower. Keep an eye out for pests, and have some insecticidal soap on hand, just in case.