FARGO — Did you hear about the guy who tried to teach mathematics to his houseplants? The plants enjoyed the conversation, but ended up with square roots.

If you have houseplants in your home, you’re part of the world’s most popular gardening activity, based on participation. Think of the immense number of us worldwide living in houses, apartments and condos who are growing at least a few houseplants, even if other forms of gardening aren’t options.

Where did houseplants come from? The Bible doesn’t say, “On the sixth day, God created houseplants.” The plants that we grow indoors were native outdoors, growing wildly somewhere in the world until humans decided it would be fun to bring them inside.

The secret to houseplant success is understanding where plants were native, and then duplicating those preferred conditions indoors. Plants are much like people, and an old adage, “There’s no place like home,” applies to both. Houseplants will thrive indoors if we provide the care to which they were accustomed outdoors in their native habitat.

A houseplant's native origin gives important clues to its preferred care. David Samson / The Forum
A houseplant's native origin gives important clues to its preferred care. David Samson / The Forum

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How can we duplicate a plant’s native origins? The majority of houseplants were domesticated from tropical regions with warm, humid, jungle-like climates. A secondary but still important group includes cactuses and other succulents, many of which originated in dry, desertlike regions, but there are also jungle-type succulents. Finding out where a plant is native unlocks the secret of success for its care indoors.

Houseplants native to the tropics will enjoy the following:

  • Organic material quickly builds and then quickly decomposes in lush jungle rainforests. For native houseplants, potting mixes high in organic material such as peat moss provide a soil to which they’re accustomed.
  • Potting mixes containing slow-release fertilizer provide a similar gradual release of nutrients found in decaying organic material of the tropics, as does organic-type fertilizer fed to houseplants.
  • Although rainfall is generous in tropical climates, the organic component drains well. If houseplants are potted in soil that remains heavy and muddy, plants can quickly suffer.
  • Tropical plants that are treelike in nature might be accustomed to higher light levels than lower-story plants. Shorter plants that originate on the jungle floor are usually better adapted to lower light.
  • Plants native to the rainforests are accustomed to having their foliage rinsed in warm rainwater. Even African violets, whose leaves become spotted if water is chilly, enjoy an occasional shower of lukewarm water, as they received in their homeland.
  • Plants of tropical origin are easily chilled, often causing irreversible damage if exposed to temperatures below 50 degrees. When buying and transporting plants in winter, protect them by inflating a plastic bag with puffs of air to create a warm bubble.
  • Humidity is much appreciated, instead of furnace-dried air. Plants in groupings enjoy shared humidity.
  • In the absence of natural predators, insect populations can build quickly on indoor plants, so be prepared with neem oil, insecticidal soap or systemic granules.

For cactuses and other succulents native to areas with limited rainfall, the following tips will make them feel at home:

  • Potting mixes specially formulated for cactuses and succulents duplicate the natural sandy, rocky or gravelly soil in which they originated, which drains rapidly.
  • Rot is the most common cause of failure of succulents from too-frequent watering. Imitating the desert’s infrequent rainfall is the best recipe for success. If in doubt, delay watering.
  • The thick, waxy covering of succulents helps them conserve water internally, which explains how they’re well adapted to infrequent rains outdoors, or well-spaced watering indoors.
  • Instead of potting cactuses and succulents in a decorative container that doesn’t have a drainage hole, use a well-drained pot set inside the decorative container, which allows drainage water to be seen and discarded immediately.
  • Cactuses and succulents are low-maintenance plants, but they aren’t necessarily adapted to low light. In their native habitat, light is often bright, which provides best growth.

Don Kinzler, a lifelong gardener, is the horticulturist with North Dakota State University Extension for Cass County. Readers can reach him at kinzlerd@casscountynd.gov or call 701-241-5707.