Houseplants – Tip Sheet #15

Know your rooms’ light levels. North-facing windows provide low light. East-facing windows let in medium natural light. West-facing windows can provide direct sun for a couple hours. A south-facing window provides 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 because plants may tolerate low light, but they will not enjoy it, and flowering plants will need more light.

Most plants need moderate watering but should never be completely dry or completely wet. If the pot seems light and the leaf tips are brown or the plant collapses, it is getting 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 one to two inches into the soil: If it feels cool and moist, wait to water. Leave about ¾ inch of space between the soil surface and the pot top as a reservoir to prevent spills when watering.

Always use potting soil, not topsoil or garden soil. A mix should be free draining; add vermiculite or perlite 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 an indoor plant needs. Always premoisten the soil before adding plants. You can add a top dressing of mulch or moss to conserve moisture or for looks.

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. The liquid form is best for container plants. Follow any instructions on the package label.

So many choices! Size and porosity matter. Smaller pots dry out faster, and cramped roots in a small pot dry out and will not 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.

Most plants outgrow their pots within two years, but some 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. Voila!

Watch for pests and remove them. Wash off aphids and mites. You can pick off scale and mealy bugs with an alcohol swab. For white fly, use yellow sticky traps or insecticidal soap.  For fungal gnats, water from the bottom, let the topsoil dry out, and/or use yellow sticky traps for flying adults and Bt or neem oil for larvae.

Increase light exposure if your plant is showing spindly growth. Crusty soil indicates a need to flush salts from the soil. Slow growth can mean it is time to repot. If you see leaf spots pick them off. They could be caused by a variety of things so watch how much you are watering, add light, feed, and watch to see if those changes cause improvement. For sooty mold look for the critters.

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 lyrate): 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 is 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 is 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.

Help with Houseplant Pests: http://pestsense.cahnrs.wsu.edu/

What Can Go Wrong with Houseplants: http://s3.wp.wsu.edu/uploads/sites/2076/2017/07/C064-What-Can-Go-Wrong-With-Houseplants-15a.pdf

Winter Houseplant Care: https://s3.wp.wsu.edu/uploads/sites/2073/2014/03/Winter-Houseplant-Care.pdf

Caring for Houseplants: https://extension.psu.edu/caring-for-houseplants. Check out the various houseplant factsheets on this site.

Additional Master Gardener Tip Sheets are available at kingcountymg.org. View free downloads of WSU gardening publications at gardening.wsu.edu and pubs.extension.wsu.edu