A window facing south receives the most intense sun, west and east exposures rank in the middle and a north-facing window is considered low light. (Photo provided)

The idea of taking plants from the wild and bringing them indoors seems to fly in the face of all things natural. But starting somewhere around 1,000 BC, plants and small trees were being used as ornamental features in homes in several ancient civilizations.

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A brief history

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We know, from early paintings and sculptures, that the ancient Greeks and Romans grew plants in containers and that in ancient India, Japan and Egypt, potted ornamental plants were commonly placed in courtyards and home gardens. It really isn’t much of a stretch then to hypothesize that some of those plants were taken into homes. In fact, evidence of wild plants being successfully cultivated indoors can be found in ancient Egyptian writings. And for centuries, the Japanese have employed the dwarfing of trees and other plants for room ornaments, a practice known as bonsai tree cultivation.

Propagating houseplants continued without much mention until 1652, when Sir Hugh Platt, an English agricultural authority, wrote about growting plants indoors in his book, “The Garden of Eden.” After the book was published, greenhouses and conservatories were built across Europe to house exotic plants collected and chosen for their remarkable foliage and/or flowers.

Houseplants remained a symbol of wealth until the end of World War II, when they exploded in popularity among hobbyists. Many modern-day gardeners, with their ability to manipulate in-home environments and control the amount of water and nutrition offered to plants, have made houseplants an essential part of their homes’ winter decor. In fact, raising houseplants has become one of North America’s fastest growing indoor hobbies.

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Care and cultivation

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Successful cultivation and care of houseplants doesn’t have to be complicated, but success can’t be achieved unless the plants you start with are healthy and free of pests. And even the healthiest plants will not survive unless they’re given the amounts of humidity, water, fertilizer and light that they require.

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Temperature and humidity

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Most houseplants will grow adequately at temperatures of 65-75 degrees. Cooler nighttime temperatures may further stimulate growth, although this doesn’t hold true for all plants. African violets, for example, may suffer if temperatures fall below 60 degrees for prolonged periods of time.

Bear in mind that plants grown on cool windowsills may be exposed to cold drafts or sudden freezing conditions. Some may suffer injury after just a few seconds of exposure. And since most plants will not tolerate hot air blowing on them, indoor gardeners should avoid putting plants near heating ducts.

Almost all plants native to temperate or subtropical environments require relative-humidity-levels of about 40% to 50%. This is also a preferred relative-humidity-level for human health. Many tropical plants will adapt to this humidity-level, but there are those that demand relative-humidity as high as 90%.

During winter months, relative-humidity-levels in homes can be as low as 10%. Almost all plants, other than desert plants, will wilt when exposed to low-humidity for prolonged periods, even when the soil they’re growing in contains adequate moisture.

Humidity levels can be increased by using a humidifier or by setting a pan of water on a radiator or wood stove. High-humidity-areas, such as bathrooms and kitchens, are often ideal for indoor plants.

Although misting will temporarily raise humidity-levels, the added moisture will evaporate quickly and minerals in tap water may cause unsightly water spots to appear on foliage. Keep in mind too, that softened water should never be used; that some plants are quite sensitive to fluorides; and that chlorinated water should be allowed to sit overnight before it’s used in misting or watering.

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Watering

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Houseplants need to be watered thoroughly. Water should always be room temperature and soils should be allowed to dry between waterings. Excess water should be able to drain and should be removed immediately. Houseplants must never be allowed to sit in standing water.

Never assume that a wilting plant needs water. When soils become saturated, roots can rot, causing wilting and eventually death.

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Fertilizer

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Most gardeners agree that houseplants need very little or no fertilizer at all during winter months. Those that do feed their plants use dilute solutions of complete and balanced water-soluble-fertilizers and keep feeding to a minimum. The idea is just to maintain the plants until longer days and warmer conditions return.

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Lighting

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Availability of natural light may well be the indoor gardener’s most important consideration. And in most cases, unless you can provide supplementary light, it’s best to select plants that require medium- to low-light.

Snake plant, Chinese evergreen, cast iron plant, and English Ivy are examples of houseplants that do well in low-light-environments. Begonia, Jade Plant, Spider Plant, and Philodendron prefer medium-light. Geraniums, Kalanchoe and Poinsettia prefer bright-light.

Plants receiving light from a window may need to be turned from time to time. Symptoms of insufficient light include small leaves, leggy, thin stems and a pale-green to yellow color.

Supplementing natural light, with artificial light from either LED or fluorescent lamps, will help. Both LED and fluorescent lights produce very little heat. They also produce light over a broad range of the visible spectrum. Only a few hours of supplemental lighting will be needed in well-lit settings, while plants growing in darker locations may require as much as 16-hours of artificial light.

Maintaining a proper distance between the plants and the light source; roughly 6-to 24-inches; will helps to ensure healthy plant growth.

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Keeping plants clean

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Keeping foliage clean will allow plants to take full advantage of the amount of light that’s available to them. By cleaning houseplants, you also improve their appearance, stimulate growth, and help control insects and mites.

Always wash foliage with a soft cloth or sponge, using room-temperature to lukewarm-water and, if desired, a very small amount of mild (insecticidal) soap. Avoid washing hairy surfaced plants like African violets and begonias.

Visit https://franklin.cce.cornell.edu/gardening-grounds/houseplants for more information.