Bonnie Power, a Massachusetts Master Gardener and member of the Massachusetts Master Gardener Association’s Speakers Bureau, gave an entertaining presentation, “What’s Wrong with my House Plants?” at Acton Town Hall on February 4, 2025. Her expertise, photos, comics and insights on how plants are different from humans regaled the audience. If you missed this presentation, here’s a valuable list of tips and tricks on how to diagnose and treat your plants, with a few misconceptions dispelled.
- Light – If your plants are dropping leaves, turning yellow, and have thin stems, then your plant needs light. Move your plants to get the light they need to thrive… Through photosynthesis, [plants] convert light and carbon dioxide to oxygen and sugars to make their dinner and live. Without pupils to adjust to light conditions, plants see light “darker” than the human eye does and need our help to place them where they will thrive.
Full sun is directly in front of the window; light from the south and west is what most plants desire. Part sun is indirect light, on an angle, from an eastern light source, and is good for some plants such as African Violets. Full shade is light greater than three feet from a northern light source and is essentially dark to most plants.
Plants want to “see” out the window to get light. Set them level with your windowsill, and less than three feet from the window. Light decreases exponentially every three feet from a light source or window. Keep them close to the light source to give them the light they need. Pull the blinds all the way up. Blinds cut available light by 50%.
Light doesn’t bend down or around the corner to the plant on the floor. Plants do not do well as decorations on shelves, in corners, or below the windowsills, as they only receive reflective light in those locations. Skylights are 12 feet above the plant, providing about six percent of the light, and are not a useful light source for plants. Use windows. Put your plants outside when the weather permits. The shadiest place outdoors is better than indoors.
Remember, light intensity changes throughout the year, so consider and adjust your plants’ locations.
LED daylight spectrum light bulbs, or grow lights, work for most needs unless you are trying to get a plant to fruit. Plants need dark to rest, so if you are using grow lights, put them on a timer for 12 hours of light and 12 hours of dark to simulate night.
- Water – In general, water your plants “weakly, weekly”. Get to know your plant by learning the signs of thirst, letting them get thirsty, and then determine when to water them.
Water deep and infrequently for good root growth. Let the water run through the pot and come out the bottom. (no paragraph change)
Giving frequent sips of water to your plant leads to shallow root growth. Watering your plant deeply and frequently leads to weak roots and root rot.
The simplest test for watering is the “fingertip” test. Stick your finger in the dirt. If it comes out dry and clean, water. If it comes out muddy, you’re ok. If the pot is light, water. If the pot is heavy, the soil is moist, so consider holding off.
Tap water is good for most plants, although carnivorous plants such as Venus Flycatcher may require distilled water. Fluoride can accumulate in plant soils and may cause browning of the tips, which can be addressed by showering the plant and rinsing the soil.
- Drainage – Plant roots need oxygen and water to percolate through the soil to the roots. Pots need good drainage. Drill holes in your pots. Use coffee filters, dryer sheets, or newspaper to prevent soil from leaking out if needed. Don’t use rocks in the bottom of your pots. The wettest soil is at the bottom of the pot. Gravel moves the wettest soil closer to the roots, which can lead to rot.
- Food – Fertilize your plants during their active growth phase from April until September. Use a balanced 5-10-5 fertilizer (Nitrogen-Phosphorus-Potassium). Organic seaweed fertilizer is not medicine. Do not feed a sick plant.
- Soil – Use good potting soil, not garden soil, which can contain fungus or insect eggs and does not drain well. If you have new plants, don’t rush to repot. They need two weeks to acclimate. Repotting stresses the plant. Let them sit, then repot. Plants don’t like to be root-bound. If you are repotting to a bigger pot, slice off roots. Do not wash the roots as it will damage the root hairs. There is no such thing as a pot too big.
- Pests – Aphids, mealy bugs, spider mites, scale, gnats were discussed, with remedies such as washing aphids away; removing with Q-tips, alcohol and water; hanging sticky traps; removing damaged parts; and using Neem oil and insecticidal soaps. It’s best to consult a good resource. Do not use dish detergents.
- Mechanical Damage – Remember, the leaf is the energy source. Do not cut green leaves to “save” energy. Let the plant grow two new leaves before trimming old leaves. Trim broken stems and leaves.
- Resources – Seek reliable information from the internet at “.edu” sites.
Use “.com” websites only if they are known to be reliable and provide references.
Here’s a List of Don’ts:
- Don’t use plants as decorations without regard to light.
- Don’t mist; it only works in greenhouses.
- Don’t put rocks in pots; it raises the water table, leads to “wet feet”, and rots roots.
- Don’t use dish detergents for insect control.
- Don’t repot when you bring the plant home – unpack, locate 2-3 days, acclimate, then repot in 14 -21 days. Don’t damage the root hairs when replanting.
- Don’t cut off leaves that are still green to “save energy”.
- Don’t fertilize a sick plant.
- Don’t use water bulbs – (except as decorations).
- Don’t fall for fads such as “banana water”.
Acton Garden Club presents a series of lectures throughout the year for the education and enjoyment of the community and the club members. On March 4, 2025, at Acton Town Hall, the club presented, “How to Build Your Very Own Hometown National Park.” To learn more about the Acton Garden Club, go to ActonGardenClub.org or Facebook. We hope you join us at one of our lectures.
Ann Marie Testarmata is the Acton Exchange’s correspondent from the Acton Garden Club.