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Tip Sheet #15: Houseplants

Houseplants are today’s original container gardens. It is rewarding to see a living thing thrive under our care, and we have environments that can help us do this. It is important to pick plants that fit your environment and your ability to care for them. First evaluate your environment to find a match for your plant’s needs and what you can and will offer.

Light

Know your rooms’ light levels. North-facing windows are generally low-light. East-facing windows, overhead lighting or good indirect light are medium light. South or west-facing windows are generally bright light. Keep in mind that seasonal changes may cause you to move your plants. If your light is less than ideal, consider grow lights.

Water

Most plants need moderate watering, but never completely dry or completely wet. If the pot seems light and the leaf tips are brown or the plant collapses, there’s too little water. If the pot is heavy, the plant droops and the lower leaves turn yellow or brown, reduce watering. The best test? Insert your finger 1 to 2 inches into the soil, and if it feels cool and moist, wait to water. Some people like to use a water meter to assess soil moisture. Leave about ¾ inch of space between the soil surface and the pot top as a reservoir to prevent spills when watering. If your soil becomes completely dry, it can become hydrophobic-that is, it actually repels water. Water thoroughly, and break up soil if it has become too compacted.

Soils

Always use potting soil, not topsoil or garden soil. Sterilized soils will prevent disease and weed seeds from contaminating your plants.A mix should be free draining; add vermiculite (for more moist soils) or perlite (for drier soils) to improve drainage if needed. Heavy potting mix creates problems like root rot because it takes too long to dry out, and roots cannot get enough oxygen. Soilless potting mixes help create the conditions that can meet the water and air requirements of indoor plants. Always pre-moisten the soil before adding plants. You can add a top dressing of mulch or moss to conserve moisture or for looks.

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Nutrients

If you want flowers, you need to feed. For general plant health, fertilize regularly during the growing or bloom season and taper off during dormant periods to let plants rest. Use diluted fish emulsions or specific houseplant fertilizers, and the liquid form is best for container plants. Do not overfertilize. Pests like aphids thrive on lush new growth.

Pots

So many choices. Size and porosity matter. Smaller pots dry out faster, and cramped roots dry out and won’t grow. Clay is cheap but it breaks. Plastic and fiberglass are lightweight, relatively inexpensive and come in many shapes and colors. Ceramics are colorful. Polyurethane resembles heavier materials but resists chipping. Consider self-watering or double-walled containers indoors. Cache pots are a great option for managing large plants or heavy pots.

And Repot

Most plants outgrow their pots within two years, but many houseplants do not mind being root-bound. Repot into a slightly larger pot that will not hold more water than the plant can use. Know your plant’s needs. Repot during the growing season, remove the plant, gently pull the roots apart, remove dead or damaged roots, fill the pot with new, premoistened potting soil and replant.

Pests and problems

  • Quarantine and monitor new indoor plants.
  • Watch for pests and remove them. 
  • Wash plants in the shower or sink with lukewarm water to remove aphids, honeydew, and sooty mold.

Refer to WSU Pestsense for cultural and chemical control options.

More problems

  • Spindly growth = add light
  • crusty soil = flush the salts from the soil
  • slow growth = may be time to repot
  • leaf spots = pick leaves off, watch the watering, add light, feed
  • sooty mold = look for the critters.

Popular houseplants

Here are a few plant choices that can recover from benign neglect or too much attention. All plants need care, so read about your plant before you buy to be sure you can meet its needs. It is easier to care for your plants if you group those with similar watering needs.

  • Fiddle leaf fig/Ficus lyrata – bright light, moist soil and repot every couple of years. It can get big!
  • Swiss cheese plant/Monstera deliciosa – another big plant that needs bright light but is easy to grow. Leave 1 to 3 plants in the pot. The leaves start to split as the plant ages, so be patient.
  • Boston fern/Nephrolepis exaltata – medium light, moist soil. It likes to move outside in summer.
  • Elephant ear/Philodendron – medium light, allow soil to dry, move outside in summer. It’s a vine so it may need support.
  • Snake plant/Sansevieria – medium light, allow soil to dry. This hard-to-kill plant makes a great backdrop.
  • ZZ plant/Zamioculas zamiifolia – low light, allow soil to dry. It is practically indestructible but toxic.
  • Chinese evergreen/Aglaonema – low light, moist soil. Keep it warm, foolproof!
  • Devil’s ivy/Pothos/Epipremnum – low light, allow soil to dry. It’s bi-colored and looks good hanging.
  • Peace lily/Spathiphyllum – low light, moist soil. Feed it to encourage blooming.
  • Dumb cane/Dieffenbachia – low light, allow soil to dry. It will need a repot every couple of years.
  • Sedums – never overwater. Try grouping these plants, pick the ones you like. Move outside in summer.
  • Air plants, bromeliads, orchids – so many choices. Read the labels and choose the colors and styles you like.

Websites with good information on houseplants