Category Archives: House plants

Indoor Plants & Clean Air

 

Over thirty years ago, NASA began researching methods of air purification in space crafts to pave the way for long-term human space flight. The study, found here, concluded that many common houseplants are highly effective at removing toxins such as benzene, formaldehyde, ammonia, xylene and trichloroethylene. The findings have been replicated many times over. Their relevance today is unmistakable, especially given the number of man-made products which off-gas chemicals in our homes and workplaces, current energy-efficient construction practices, our focus on healthy living and concern for the environment.

The following are answers to commonly asked questions about the relationship between clean air and indoor plants.

How exactly do plants clean the air?

Plants are effective at absorbing gases through pores on the surface of their leaves. It’s this skill that facilitates photosynthesis, the process by which plants take in carbon dioxide and release oxygen. In effect, all plants can purify the air to some extent, but some do a better job than others.

Studies show that plants can absorb many gases, including a long list of volatile organic compounds (VOCs). Benzene (found in some plastics, cloth and pesticides) and formaldehyde (found in some cosmetics, dish detergent, fabric softener and carpet cleaner) are common indoor VOCs that plants help eliminate.

Plant roots and the microorganisms that live in healthy soil also absorb VOCs and other pollutants.

Which plants were used in the NASA study?

Most were common, easy to care for plants which you may have in your home or office right now. Top “air filters” included: Peace lily (Spathiphyllum wallisii), golden pothos (Scindapsus aures), mother in law’s tongue (Sansevieria trifasciata ‘Laurentii’), bamboo palm (Chamaedorea sefritzii), dracaena (Dracaena marginata), spider plant (Chlorophytum comosum), English ivy (Hedera helix), Chinese evergreen (Aglaonema commutatum). Gerbera daisies (Gerbera jamesonii) and potted mums (Chrysantheium morifolium) are also effective air purifiers, but tend to be short-lived flowering houseplants.

Can plants reduce the harmful effects of cigarette smoke in the air?

Cigarettes contain formaldehyde, one of the toxins that plants can remove from the air. However, the plant/cigarette smoke connection was not the focus of the NASA study. A 2010 study by the American Society of Horticulture Science found that ferns were among the most effective plants in formaldehyde removal.  Check out the study for specifics on which ferns offer the best results.

Do I need to live in an indoor jungle to reap benefits?

Hardly! Studies found that approximately one 6″ to 8″ pot per 100 square feet, or 15-18 plants per 1800 square foot house makes a measurable difference.  The more vigorous the plant, the more pollutants it will draw from the air.

 

Photo credits: Bing free images

Written by: Linda McDonnell, a Denver County Master Gardener

 

 

 

 

 

Advertisements

Shedding Light on Houseplants

20160201_134705

Daylight saving time is on hiatus, the gardening season has drawn to a close and  the long shadows of winter will soon be here.  It seems like a good time to turn our attention to the light needs of indoor plants.

Most indoor plants hail from the tropics, making their ideal growing conditions far different from what we offer in our typical homes. Thin new leaves, loss of lots of older foliage and limbs stretching towards a window can all be signs that your plant is craving more light. Without adequate light plants are unable to store energy for growth.

Indoor light is more subtle than the light in our gardens, which can make it trickier to assess. For more precision, a photographer’s light meter or a simple light meter app on your phone will measure the light in foot-candles or LUX units. Horticulturists use foot-candles, so if you have a device which gives a LUX reading, search the web for an easy LUX to foot-candle calculator.

In general, growers characterize plants as needing high, medium or low light.  Here are some guidelines to help assess the type of light in your environment with greater accuracy.

High Intensity Light

  • 1,000+ foot-candles
  • 4-6 hours of sun per day
  • Crisp shadows and dark contrast at the brightest time of day
  • Within 2’ of east facing windows
  • Within 2’ of south-facing windows (October-March)

Medium Intensity Light

  • 500+-1,000 foot-candles
  • Within 2’ of north facing windows (April-September)
  • 2-6’ from an east or west-facing window
  • 1’ to the side of an east or west-facing window
  • Approximately 10-14 hours per day of fluorescent office light

Low Intensity Light

  • 50-500 foot-candles
  • Faint shadows at the brightest time of day
  • Within 2’ of north facing windows (October-March)
  • 6-10’ from south-facing windows (April – September)
  • Few plants survive in fewer than 50 candles

Knowing the light intensity will help determine the best placement of  plants and select  plants which will thrive. Variables such as humidity, drafts and temperature also factor into a plant’s health, so be sure to take this into consideration, too.  As always, knowledge and keen observation skills are key to successful plant care.

Additional information on plants and light:

Plantalk 1352: Interior Plants and Light

Plantalk 1314: Houseplants: Artificial Light

Starting Seeds Indoors

Christmas Cactus Care (effects of light on bloom)

 

Written by Linda McDonnell, a Denver County Master Gardener

 

 

 

 

A Poison Plant Primer for Halloween

While on a garden tour a few years ago, I crossed over to the dark side. Instead of admiring the frilly flowering ornamental plants, I spent my time inside the Poison Plant garden. 

The gate, decorated with a large iron spider in a large iron web, creaked eerily on opening and then slammed shut behind me.

The spider signified the potential dangers that grew inside that garden, like Oleander (a glycoside). This innocent-looking plant can cause respiratory difficulties and heart problems. Although this Mediterranean shrub can be a fragrant addition to the landscape, every part of the plant is poisonous when eaten. The smoke is also toxic if plant parts are burned.

Other glycosides in the garden included foxglove and lily-of-the valley.

Why would a perfectly nice botanic garden include harmful plants among the others? For the same reason so many other plants are on display: to educate gardeners and the general public.

We can’t escape poisonous plants because they can grow anywhere. Jimson weed and nightshade; soapwort and poison ivy; stinging nettle and even St. Johnswort were a few of the other plants growing in the garden.

“A recent increase in herbal usage has given rise to misuse and mistaken identities,” explained a sign near the poison garden’s entrance. “It is important to consider means of preventing a toxic encounter as well as enjoying the contributions of poisonous plants around us.”

Because Halloween is a time for delightful frights, I recommend taking a read through Amy Stewart’s entertaining book called “Wicked Plants: The Weed that Killed Lincoln’s Mother & Other Botanical Atrocities” (Algonquin Books of Chapel Hill, 2009).

She includes poisonous plants familiar to most gardeners, like Castor Bean, Henbane, Hemlock and Deadly Nightshade. But she also includes some surprises like Habanero Chile, Sago Palm, Tobacco, Junipers and Bermuda grass.

“We assume if it grows out of the ground, a plant is natural and natural is good for you,” says Amy. But cyanide is also a natural substance that comes from some plants, and it definitely isn’t good for you.

Speaking of deadly plants, what do you think is the world’s most wicked plant? Scroll past the following poison plant resources section to learn the answer.

Resources

A nice addition to Amy’s book is a list of poison gardens throughout the world and a well-research bibliography with many poisonous plant resources and identification guides. Here are a few links to help get you started:

CSU’s Guide to Poisonous Plants database lists trees, shrubs and perennials that can be harmful to animals.

Cornell University’s College of Agriculture and Life Sciences has a searchable database of plants that are poisonous to livestock and other animals. The color images help with plant identification.

The University of Illinois Extension has a comprehensive list of links to poisonous plant information. 

The World’s Most Wicked Plant?
Tobacco

By Jodi Torpey
Denver Master Gardener since 2005

A Year in the Life of an Amaryllis

amaryllis_akaIf your holiday amaryllis is nearing the end of its blooming cycle, here are tips to enjoy the plant through the year and give it the best chance to bloom again. Unlike paperwhites, which are one-and-done indoor bulbs, with care, amaryllis can re-bloom for years to come.

While flowering, the plant benefits from bright, indirect light and moisture. When each trumpet-shaped flower is finished, snip it off and when the last flower on the stem has shriveled, cut the entire stem about an inch above the bulb. Leave the strappy leaves in tact. Occasionally amaryllis won’t develop leaves until after blooming, so don’t fret if the plant is foliage-free at this stage. However, adding fertilizer to a bulb without leaves will kill the roots.

Treat the bulb as a houseplant throughout the winter by providing direct sunlight, watering when dry below the soil line and feeding common houseplant food once or twice a month. The bulb should remain snuggled in the original pot, with the top half to one-third above the soil line. In spring, the leaves will yellow and die, signaling that they’ve done their job of providing nutrients to the bulb, a common bulb process. Cut the foliage about an inch from the top of the bulb; new leaves will emerge through the summer. Leaves equal energy, so the more leaves developed at this time, the more vigor the bulb has to flower again. During the summer months, you’ll want to give the pot as bright a spot as possible, either indoors or out. Burying the pot in a partially shaded garden bed is also an option.

In September, reduce water significantly until leaves turn yellow and die. Store the plant in a cool, dark area (45 to 50 degrees) for 8-12 weeks, checking regularly for signs of new life and watering sparingly. This fall “Goldilocks” phase of not-too-hot, not-too-cold is critical to the forcing process so choose the resting spot carefully. When you see fresh growth, move the plant to bright light and resume regular watering. The plant is now ready to produce new foliage and flowers.

Many find this process a snap. If that’s not the case for you, keep in mind that the size and quality of the bulb can effect re-blooming, so from the start choose large, blemish-free bulbs which are heavy relative to their size. Amaryllis forced in water are also unlikely to re-bloom as they lack the energy to survive. But if this experiment doesn’t work for you, you may not want to give up as the bulb can take a year off from flowering and then come back with a vengeance. Growing amaryllis sure can be an exercise in patience!

Posted by Linda McDonnell, a Denver Master Gardener

Christmas Cactus Care

chistmas-cactus

Let me start by saying I’ve killed my share of houseplants, but one that has lived for close to three decades is the Zygocactus. Commercially, growers sell two slightly different plants as Zygocactus: the Thanksgiving cactus which has pointy edged branch segments and blooms around turkey time and the Christmas cactus which has rounded segments and blooms for its namesake. Care for the plants is essentially the same. Mine, shown above, is the Thanksgiving variety, Schlumbergera truncate.  Through periods of  neglect, inconsistent feeding and infrequent (twice maybe?) repotting, this plant keeps blooming prolifically year after year. I’ve rooted cuttings several times as gifts, but curiously, its offspring have rarely flowered in their new homes, where I might add, they get more TLC than they would living with me. This begs the question, what does this plant need to thrive and re-bloom? Here are the best tips from the experts and a few of my own observations.

  • It likes a bright, but not sunny location with temperatures that do not drop below 60 degrees.  Mine moves from indoors to an east facing screened porch from Memorial Day till Labor Day, or longer if the fall is mild like it was this year.
  •  It is a cactus which likes humidity. Unlike most cactus which prefer dry air, it hails from the tropical rainforests of South America and likes moist air. Sitting the plant on a pebble tray with water that does not touch the bottom of the pot can help, or living in a kitchen or bathroom would be ideal.
  •  It wants good drainage. If repotting, use standard, well draining potting soil. Water when it is dry just below the soil line, about once a week. I’ve  found  it amazingly forgiving if  when I forget to water. Over-watering will cause branches to rot, so more is not always better.
  • Spring and Summer are its active growth times. Prune when it is done blooming or in early summer to promote side branching. Cuttings can easily be rooted in water or soil. Adding houseplant food during the growth period helps. I have cut back branches to about six inches in the spring and the plant tripled in size by the end of the summer.
  • Here’s the key! It needs longer autumn nights to rebloom. Photoperiodism is a plant’s reaction to periods of light, similar to our circadian rhythm. Starting in mid to late September, the Zygocactus needs between nine and twelve hours of uninterrupted darkness each day in order to flower. Thanksgiving cactus take about six weeks of longer nights to sprout buds, Christmas cactus need about eight to twelve weeks.  This longer “sleep” period is the trickiest part of the reblooming process and why the porch, which is generally dark at night, works so well. Other options are to locate the plant in a similarly lit room, or  early each evening, cover it with a box or put it in a closet. Complete darkness insures maximum blooms. From experience, I’ve found that the occasional interruption of darkness reduces blooms, but will not thwart all flowers.
  • Stop the longer night process when buds emerge. The plant is now ready to flower. At this time, reduce watering slightly to promote brighter flower color.
  • Watch for bud drop. This could indicate you’ve reduced water too much. If the plant is new to you, it also could be reacting to a change in environment. Drafts or temperatures below 60 degrees may also be the culprit. I often see shriveled tiny buds at the end of the blooming cycle, as though the plant is  exhausted from the work it takes to flower for weeks on end. I found no science to support this notion, just my take on it!

Zygocactus are graceful, pretty plants, with or without blooms. Their showy, colorful holiday flowers are a beautiful treat at the end of the year. With a little extra care in the fall, they will regale you with splendid  holiday color.

By Linda McDonnell, a Denver County Master Gardener

Hardy Gardeners Make for a Blooming Great Sale

heirloom tomatoesCloudy skies and the threat of rain weren’t enough to stop gardeners from shopping for plants at the Denver Master Gardener’s annual plant sale. The  number of gardeners on Saturday surely set a record, because by Sunday morning there wasn’t a single pepper plant left on the tables.

“We have never seen as big a turnout from the public as we saw on Saturday morning,” says Merrill Kingsbury, CSU Extension Master Gardener coordinator. “The turnout was phenomenal.”

It takes months of planning and an incredible volunteer effort to make sure the annual sale is a success. In addition to the hours of planning meetings, there were days spent seeding and tending plants in the greenhouse, potting up garden grown plants, writing labels, and transporting plants to the sale.

An army of  volunteers showed up to organize tables, staff them, and then tear them down at the end of each day.

The annual plant sale is a fundraiser and also an educational outreach to the community. At the CSU Extension information table, gardeners could enter to win a hanging basket and pick up handouts on best practices for growing their vegetable gardens. A poster offered ways to deal with Japanese Beetles.

The annual plant sale is a fundraiser and also an educational outreach to the community. At the CSU Extension information table, gardeners could enter to win a hanging basket and pick up handouts on best practices for growing their vegetable gardens. Posters provided suggestions for planting creative containers, plants for butterfly gardening, and ways to control Japanese beetles.

Denver Master Gardener apprentice Susan Hoopfer offers advice for planting Milkweed (Asclepias) to a gardener interested in attracting Monarch butterflies to her garden.

Denver Master Gardener apprentice Susan Hoopfer offers advice for planting Milkweed (Asclepias) to a gardener interested in attracting Monarch butterflies to her garden.

Beginning gardeners had a chance to ask all the questions they wanted for planting their first vegetable garden.

Beginning gardeners buy plants and ask questions to get ready for planting their first vegetable garden.

At the houseplant and patio table, Barb Pitner helps a new gardener find the perfect plant.

At the houseplant and patio table, Master Gardener Barb Pitner helps a new gardener find the perfect indoor plant.

Apprentice Chad Thompson enjoyed his first plant sale by helping answer questions about annuals.

Apprentice Chad Thompson spends his first plant sale at the annuals table, answering questions and offering planting advice.

Now it’s time for Denver Master Gardeners to take a deep breath and nurse sore muscles before starting to plan next year’s sale.

Living With Plants and Pets

20160126_123421[4]Keeping pets safe around house plants has been on my mind with the adoption of Chance, a charming, spirited feline. His only plant-related indiscretions (so far) have been a few nibbled leaves, a toppled jade and a snatched spider plant baby. Then there’s the twinkle in his eyes when he gazes up at the six-foot tall ficus tree, which makes me think he’s plotting something.

Ivy sitting by plants

Many find discouraging dogs and cats from digging or eating plants can be accomplished by moving plants to less trafficked areas; lightly covering the soil line with rocks, shells, or screening; sprinkling cayenne pepper or bitter apple spray around the leaves or lending the plant to a friend until the pet matures. Some cat owners grow wheat grass as a treat and a distraction from other plants.

If ingested by dog or cats, house plants can be toxic and trigger reactions ranging from mild discomfort (such as vomiting or diarrhea to release the toxin) to more serious illnesses. Some to be aware of are:

Dieffenbachia– Dogs and cats can react to eating leaves with intense burning in the tongue and mouth, difficulty swallowing, drooling and vomiting.

Corn Plant – the leaves contain saponin, which ingested in large amounts causes dogs and cats to vomit, lose appetite, have increased salivation and even show signs of depression. Cat’s pupils may also dilate.

Lillies – Many varieties, including peace lilies, are toxic to dogs and cats, although cats have more severe reactions including kidney failure and death if not treated. Easter  lilies and common florist varieties are very toxic to cats.

20160201_134705

Peace Lilly

Often cat owners prefer not to bring lilies into their  homes.

Cyclamen – The tuber  (the pod-like structure just under the soil) contains the poison, not the leaves or flowers. Reactions can include abnormal heart rhythm and seizures.

20160201_135054

Cyclamen

 

  • DSCN0546[1]

    Jade

 

 

 

 

 

 

Jade – Dogs and cats react to eating the fleshy leaves by vomiting, or in more extreme cases by losing coordination and a lowered heart beat.

The ASPCA website contains a far more extensive list of toxic and nontoxic plants for both home and garden.

Should your pet become seriously ill from eating a plant, promptly contact your vet or the  ASPCA hotline,888-426-4435.

Pets frequently out grow their plant-loving stage as they mature, although avoiding the most toxic plants will give you peace of mind  and keep your friend from temptation.

Any suggestions for keeping pets safe around house plants? We’d love to hear from you.

Submitted by Linda McDonnell, Denver Master Gardener, with thanks to models Ivy and Chance.