GARDEN HOTLINE | The gift of health, fresh air

During a typical winter day, our region’s coveted day length averages 8.5 hours, with 77 percent of that daylight filtered through clouds. Many of us turn to indoor hobbies for entertainment until the sun returns to our gardens outdoors. 

Fortunately, you do not need to completely forgo the pleasures of working with plants in the winter. Consider a collection of tropical houseplants — all of which are calming and pleasing to the senses, but a few are great air purifiers for indoor spaces and may also offer edible or medicinal uses as well. 

Air purifiers

In the late 1980s, NASA teamed up with the Associated Landscape Contractors of America to test the effectiveness of tropical indoor plants at removing indoor air pollutants, specifically volatile organic compounds (VOCs). In their native environments, the tropical indoor plants the scientists selected are forest understory plants, which are efficient at capturing light and processing the gasses needed for photosynthesis. 

With this observation, scientists wondered if they might also be efficient at trapping and processing other types of gasses, including indoor air pollutants. 

The three main types of pollutants tested were ones that might be of concern to on-duty astronauts in enclosed environments. Incidentally, these also happen to be chemicals that can be of concern to earthbound people: chemicals found in cleaning and building materials, including benzene, formaldehyde, trichloroethylene and carbon dioxide. 

Scientists tested 19 different houseplants and discovered that, while all of them showed some efficiencies with removing air pollutants indoors, some were particularly more effective at removing one chemical over another. 

The study concluded with the recommendation to use a diversity of species to maximize the range of pollutants mitigated and to include at least 15 plants in any home 2,000 square feet or smaller. For a larger home, just think bigger! 

The best indoor plants for air purification:

•Heartleaf philodendron (Philodendron scandens oxycardium)

•Spadeleaf philodendron (Philodendron domesticum) 

•Cornstalk dracaena or corn plant (Dracaena fragrans ‘Massangeana’) 

•English ivy (Hedera helix) 

•Spider plant (Chlorophytum comosum) 

•Janet Craig dracaena (Dracaena deremensis ‘Janet Craig’)

•Warneck dracaena (Dracaena deremensis `Warneckii’) 

•Weeping fig (Ficus benjamina) 

•Golden Pothos (Epipiremnum aureum) 

•Peace lily (Spathiphyllum sp.)

•Splitleaf philodendron (Philodendron selloum) 

•Chinese evergreen (Aglaonema modestum) 

•Bamboo palm (Chamaedorea sefritzii) 

•Snake plant (Sansevieria trifasciata) 

•Red-edged dracaena (Dracaena marginata) 

All of these plants are easy to grow indoors, preferring lower light settings. Keep them away from a cold windowsill but close enough to benefit from the bright light of an unshaded window. They do not need direct sun on their leaves. 

Be sure to keep them away from direct hot-air flow like a furnace vent or too near a fireplace and to keep them dusted and clean to avoid a spider mite infestation. 

In terms of design, they all have different growth forms, varying in width and height and also in leaf texture, pattern and color. This diversity allows ample options for where to fit them into your home décor. 

Edible, medicinal indoor plants

Certainly, a far shorter list of plants will grow easily indoors and also yield some leaf, root or flower for tasty eats or natural healing. 

•Aloe (Aloe vera) — This succulent gem has been grown for its medicinal gel in so many regions of the world that its origin is unclear. 

The cooling inner-leaf gel is applied to topical burns and contains six natural antiseptics to help heal minor scrapes. Aloe is found in numerous beauty products and health food store elixirs to refresh your skin and soothe your digestive system. 

The plant itself likes bright light, a sturdy pot and a very particular irrigation regime: a deep soaking, followed by ample time for the soil to completely dry out before the next watering. 

•Ginger (Zingiber officinale) — Pick up a nursery plant start, fully grown out, or select an organically grown root from your local market to start a ginger plant. 

Pick a root with visible “eyes” or growing nodes. This is where the plant will send out new shoots. 

Soak the root in water overnight, and then place the whole root into a pot of organic potting soil. You can cut the root into sections with eyes to fit into a pot if needed. 

Ginger is useful for symptoms of a common cold, for stomach nausea or menstrual cramps and warms your body by stimulating circulation on a cold winter day. 

Ginger root adds zest to main dishes, holiday confections, healthy fruit and veggie smoothies and herbal tea blends. The root can be used fresh or dried, but brace yourself to know that by harvesting the root you need to sacrifice the plant; be sure to save a piece of the rhizome to grow your next batch. 

Ginger leaves are also useful and can be chopped finely to add to soups or use as a garnish on a rice-based stir-fry. 

As a plant, ginger likes high humidity, bright indirect light and warmth — great for a kitchen or bathroom. 

•German chamomile (Matricaria recutica) — Here’s an easy, little kitchen windowsill plant to help you snooze this winter. Chamomile is calming and anti-inflammatory and has a sweet and earthy aroma. 

Start with a packet of chamomile seeds and sow 10 to 15 seeds in a 4- to 6-inch pot filled with moistened organic potting soil. Place a piece of plastic over the top to keep the humidity up, and spray the soil surface only when it begins to show signs of drying out. Once the seeds have germinated, take off the plastic and let them grow. 

This chamomile is an annual plant, setting seed in one growing cycle. The flower is your medicine, so aim to get this little plant to bloom. 

Indoors, chamomile can grow to 10 inches in height before flower buds appear. Keep it in a sunny window, water as the soil dries and trim the flowers for harvest. You might need to re-sow once or twice to keep enough growing for harvesting through the winter. 

FDA disclaimer: The information presented here has not been evaluated by the FDA and is for informational, reference and educational purposes only. It should not be interpreted as a substitute for diagnosis, prevention and treatment by a health-care professional. Always consult a qualified physician before making any herbal modifications.

To learn more about choosing the right plants, indoor pest management and using sustainable tools for indoor gardening, contact the Garden Hotline at (206) 633-0224 or www.gardenhotline.org.

LAURA MATTER is the program coordinator and an educator for Seattle Tilth’s Garden Hotline.