Dear Master Gardener: What are easy to care for indoor plants that will brighten these dark winter days and nights? Is there any research about plants being beneficial?
Answer: Green plants and flowers can cheer us up, especially during the long, dark days of winter. Growing houseplants is a very popular hobby right now and there are some interesting, new plants available. There are research studies that have shown that interacting with indoor plants often reduces physiological and psychological stress. Several studies were conducted at the University of Exeter in 2013 and 2014 which found that plants in the workplace improved productivity, concentration and a feeling of well-being. The 2014 study compared two large commercial offices with no plants versus “green” offices on the staff’s perceptions of air quality, concentration and workplace satisfaction, and monitored productivity levels. A University of Michigan study concluded that studying and working in the presence of plants increased concentration, memory, and productivity. Their study showed that memory retention increased up to 20%. Another study at Texas A&M also found that working and studying around plants produced better quality and higher accuracy work.
The National Institute of Health led a clinical trial with surgical patients that evaluated whether plants in hospital rooms had a therapeutic influence. Patients who were in post-operative recovery were assigned to control or plant rooms. The data indicated that patients in hospital rooms with plants and flowers had significantly more positive physiologic responses (lower systolic blood pressure, and lower ratings of pain, anxiety, and fatigue) than patients in control rooms. Patients with plants had more positive feelings about their rooms and evaluated them with higher satisfaction compared with those in similar rooms without plants. Based on patients' comments, plants brightened up the room environment, reduced stress, and even gave them more positive impressions of the hospital employees caring for them.
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A popular NASA study did prove that certain houseplants can remove some air pollutants commonly found in the home, such as formaldehyde, carbon monoxide, benzene, and trichloroethylene. However, for plants to be effective at cleaning the air, you would need one plant in every cubic foot! Your house would look like a jungle, and there would be no room for you, but on the flip side, you would add moisture to your dry, winter home! So yes, there is research showing that plants can be beneficial in some ways. Personally, plants give me that nature fix I need to get me through a long, frigid winter. I always seem to justify buying more plants by thinking it’s good therapy!
The biggest challenge in the winter here in Minnesota, is having enough light for your plants without putting them too close to cold windows. Low humidity can be overcome by running a humidifier or placing pots on pebble-filled trays with a bit of water that will evaporate upwards. Don’t mist your plants. Damp leaves are a perfect breeding ground for bacterial or fungal diseases.
The following houseplants are very easy to grow: Croton, Chinese evergreen, Dracaena, Palm, Peace lily, Pothos, Philodendron, Sansevieria (also known as snake plant or mother-in-law’s tongue), and Spider plant. Christmas cactus, Kalanchoe, African violet, and Orchids are long-lived, flowering plants with long bloom times that can also add a pop of color and cheer to your home.
Related: Ask the Master Gardener: Aloe plants offer benefits aside from their beauty
Dear Master Gardener: I have fungus gnats and try to avoid using pesticides. If I buy a carnivorous plant, will it eat all the insects?
Answer: Carnivorous, or meat-eating plants, are very interesting plants that capture and usually digest insects and other small arthropods. Some carnivorous plants that make good houseplants are Venus fly trap, sundew, butterwort and pitcher plant. Venus fly traps are very fascinating plants to watch when the leaves snap shut on an unlucky insect that happens across its path. The cup-shaped pitcher plant stores up a sweet-smelling juice, which lures unsuspecting insects to their death. The leaf's waxy interior and downward facing hairs keep the insects trapped where they eventually drown. Sundews are mostly short-stemmed plants with a rosette of foliage. Depending on the species, the leaves vary from thread-like to paddle-shaped to nearly round. The leaves are covered with tiny hairs, which exude a clear, sticky fluid. The sticky droplets trap unwary insects or other small creatures that come in contact with it. The struggling victim stimulates the hairs to bend inward, drawing it closer to the leaf where it is digested into plant nutrients. Butterwort is similar to sundew in how it catches its prey; however, it consumes only very tiny insects.
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Carnivorous plants have very specific growing requirements that are different than most commonly grown houseplants. They are bog plants and need to be kept watered, but not over-watered. They should be planted in pure peat and sand rather than potting soil and should not be fertilized. Good lighting is essential for carnivorous plants. An east or west facing window that receives at least one or two hours of direct sun is ideal. Use only distilled or rain water so no minerals are added.
Related: Ask the Master Gardener: Caring for colorful cyclamen plants
Dear Master Gardener: We moved to a house that has black walnut trees in the yard and I noticed it is hard to get anything to grow under them. Are there any perennials or annuals that will grow under them?
Answer: Black walnut trees, native throughout Minnesota and much of the United States, pose difficult gardening conditions due to the toxic juglone naturally produced by the plants. The following plants will grow under a black walnut tree: hollyhock, Jack-in-the-pulpit, astilbe, wax begonia, pot marigold, bellflower, glory-of-the-snow, crocus, snowdrop, cranesbill geranium, coral bells, Spanish bluebell, morning glory, bee balm, sundrops, cinnamon fern, garden phlox, lungwort, Siberian squill, lamb’s ear, spiderwort, zinnia, pansies, violets, daylilies, hosta, and sedum.
Related: Ask the Master Gardener: The rewards of feeding birds in the winter
You may get your garden questions answered by calling the new Master Gardener Help Line at 218-824-1068 and leaving a message. A master gardener will return your call. Or, emailing me at umnmastergardener@gmail.com and I will answer you in the column if space allows.
University of Minnesota Extension Master Gardeners are trained and certified volunteers for the University of Minnesota Extension. Information given in this column is based on university research.
