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Holiday cacti.jpgMany of us receive plants over the holidays as gifts or buy them to bring a little green into our homes during winter. Usually these plants are in full bloom and look terrific for some time. After the flowers dry up and drop off, indoor gardeners are sometimes left wondering how to care for these plants and more importantly - how to make them bloom again! Our Extension publication Cacti and Succulents has a very helpful section on "Holiday Cacti" that explains the affects of temperature and light on Christmas cactus (Schlumbergera bridgesii), Thanksgiving cactus (Schlumbergera truncata), and  - yes - Easter cactus (Rhipsalidopsis gaertneri). All three of these plants require short days and cool night temperatures to induce budding. Read more

Favorite plants for Valentine's Day

What is Valentine's Day without expounding on some favorite, romantic plants? Roses are the traditional flower to give on this day of lovers, but as many of my gardening cohorts know, orchids are one of my favorite types of plant life.

According to Orchids of Minnesota by Welby Smith, estimates note upwards to 23,000 P1210761.JPGspecies of orchids in the world (7-10% of flowering plants). In Minnesota, we have 42 wild orchids that migrated here - a surprise as we think of orchids as fragile plants and tropical. But think of our state flower - the showy lady's slipper (Cypripedium reginae) - it is an orchid and grows in ditches along our roads! These are some tough organisms - and I find them a real pleasure to grow. Today it's easy and inexpensive to buy orchids - especially moth orchids (Phaleanopsis or "phals" ). I admit to buying one of my most reliable phals at IKEA! (it was my first and pictured here in full bloom).

I have found the limitations for growing orchids as houseplants similar to other houseplants: light, water, and patience - especially true in the case of orchids. Growers also need to appreciate the whole plant - not just the blossoms - as healthy leaves and firm, strong roots mean flowers are in the future. Most orchids perform best in a bright window in the winter months and filtered sun in the summer. Moth orchids are more tolerant of lower light situations indoors (another good reason for trying one). Keep leaves clear of dust too using a soft damp cloth.

Let your orchid dry out between watering and use rainwater, melted snow, or RO water (reverse osmosis and refillable at many grocery stores). Don't use tap water as it is usually softened and treated. Add a dilute amount of orchid fertilizer each time you water and flush plants once a month with clear water to eliminate salts that have collected. Note that plants growing in sphagnum moss will hold salts in the moss, soorchid6.JPG fertilize less often. Once a plant has finished flowering, leave the flower stem on the plant till it turns brown as sometimes they re-bud. After blooming, the leaves may appear wilted and dull, but continue good care and they will return to their thick, green condition. Celebrate new leaves and the crazy silvery roots as they indicate a a healthy plant and more flowers to come.

Take a look at our publication Phalaenopsis and Paphiopedilum species: Easy orchids to grow as houseplants. A great field trip for any orchid enthusiast - beginner or expert - is to the Como Park Conservatory, the conservatory at the U of MN Landscape Arboretum or, if you need a greenhouse shopping experience (as I recently did on a -20 degree day), visit Orchids Limited in Plymouth MN.

Recently, a new Extension Master Gardener intern told how orchids grew everywhere in her homeland. All I could do was sigh.... Enjoy these pics and happy Valentine's Day!

Yes, You Can Grow Oranges in Minnesota!

Mary H. Meyer, Extension Horticulturist

Mary Meyer

Photo 1: Calamondin orange trees need maximum light, such as the south facing window, shown here. Photo taken January 4, 2014

"Oh my! How do they expect me to grow an orange tree in Pennsylvania?" my Grandmother Rena Anderson exclaimed as she unwrapped her Plant-of-the-Month gift on a summer day in the 1960's as we sat in her screened porch amid her many plants. She laughed and potted the tiny plant. Today I enjoy this same orange tree in an even colder Minnesota climate and yes, it produces oranges!

The calamondin orange ( Citrofortunella mitis) is a tough houseplant IF you have enough sunlight and can keep it watered in well drained soil. My plant spends May-October in an unheated porch with large south facing windows and the rest of the year in a corner of my living room with south and west facing windows (Photo 1).

In other words: the brightest light we can supply in Minnesota. Over the nearly 50 years since my grandmother received it, I have moved it through 5 states, 12 homes and many repottings. In October 1986, the orange tree was the last thing I put on the moving van in Philadelphia and the first thing I took off when the van doors opened in Plymouth, Minnesota a few days later.

I am attached to the orange plant as it was my grandmother's, and she was one of my plant mentors. But this orange can fill my porch or living room with a sweet orange blossom fragrance and it sets fruit well enough, that most years, I can make marmalade.

Here is a brief history of some recent orange harvests:

Calamondin Oranges ------------- Harvest Date

112-------------------------------- January 9, 2011
52-------------------------------- November 25, 2012
25-------------------------------- September 21, 2013
27--------------------------------January 5, 2014

Mary Meyer

Photo 2: 112 oranges were harvested from the tree in January of 2011.

Here is what I have learned from, yes, only 1 orange plant, over the years:

Bright light for several hours every day is necessary for citrus to do well in Minnesota. Moving the plants outdoors in the summer really helps. Gradual exposure to direct sunlight in the summer is important, as leaves that develop indoors are not able to grow outdoors unless they are acclimated; they easily get sunburned.

Adequate water is also essential. Citrus leaves are thin and easily wilt. Regular watering is essential for good growth. Just as important is good drainage, water should never stand at the bottom of the container. For many years, I used a plastic container, so I did not have to water as often, however today the plant is in a clay pot and it prefers the better air exchange for the roots.

Citus requires a lot of nitrogen and iron to grow well, and iron is often unavailable in high pH soils, which tends to happen over time with the alkaline water we use on indoor plants. Yellow foliage is a common sign of iron deficiency in citrus and means you need to add a fertilizer that has available or water soluble iron. Throughout the summer, I use a readily available, water soluble fertilizer, such as 20-20-20 once or twice a month. In the winter, I rarely use fertilizer. And about once a year, I use an iron supplement to keep the foliage a healthy green color.

After a few years of treating mealy bugs, I gave up on insecticidal soaps, which will control most insects and used a stronger systemic control that eliminated the mealy bugs. However, I did not eat the citrus for two years. Careful, regular inspection is necessary to prevent insects from becoming a problem, especially if plants are exposed to other plants or outside conditions.

Meyer lemons are also fun to grow and will produce a few lemons in Minnesota. I bought two plants a few years ago and they have produced about 5 lemons in total. These lemons take a long time to ripen (months) and are a pale orange instead of yellow when ripe. These semi-sweet lemons are a cross between a lemon and an orange, so they are much milder than regular lemons.

The tree was brought to the United States from Beijing, China in 1908 by Frank Meyer, a plant explorer of the U.S. Department of Agriculture, (no relation to me :(). The plants can be gangly and leggy plants; you should prune them after harvesting the fruit, to keep the plants in a manageable size and shape. Growing conditions are similar to calamondin oranges, however be sure to purchase plants from a reputable garden center so you do get the true Meyer, or Improved Meyer lemon.

A fun fact about citrus plants is they can have evergreen foliage, flowers, immature and mature fruit all at the same time. For Minnesota, it is fun to have fragrant flowers, and developing attractive fruits over the months when we often see too little green.

I have two daughters, and I may have to propagate my orange from a softwood cutting in the spring so they each have a plant to enjoy in their homes.

But for now, I plan on harvesting Grandma Rena Anderson's calamondin oranges for many years to come.


Growing Citrus Indoors in Minnesota


Four Winds Growers in California is one supplier for indoor citrus plants:

Karl Foord - University of Minnesota Extension

It is not often that a plant can through a visual color change indicate its need for water, however the aerial roots of tropical epiphytic orchids indeed do. Epiphytes are plants that grow on other plants or structures but are not parasitic (Photo 1).

Photo 1: Epiphytes on Tree

They derive their moisture and nutrients from air, rain and nearby debris. Most of the orchids used as house plants are tropical epiphytes.
The roots of these plants not only serve to anchor the plant to trees or stone, they also function as water storage units capturing water during rain events. The roots have a unique structure that enables them to absorb and store water. Phil Gates, a botanist at Durham University in the UK, has a blog entitled, Beyond the Human Eye - An insight into a microscopic world, invisible to the unaided human eye. He has sectioned and photographed an orchid root (Photo 2).

Phil Gates

Photo 2: Sectioned orchid root

The xylem vessels that conduct water from the roots to the leaves consist of the ring of bright yellow cells at the bottom of the photograph. Surrounding the xylem vessels is a layer of blue packing cells. Exterior to the packing cells is a row of hexagonal cells beyond which are a layer of dead cells called the velamen layer. The velamen layer functions as a sponge soaking up water as the aerial roots are exposed to rain or mist. Interestingly the velamen layer changes color based on water content and is an excellent indicator of the plant's water status. Dry velamen reflects light and is white or silvery (Photo 3),

Phil Gates

Photo 3: Dry orchid root

but when the velamen absorbs water the green tissue underneath becomes visible and the root takes on a green or mottled green color depending on the species (Photo 4).

Phil Gates

Photo 4: Wet orchid roots

The Fingerprint of a Virus

Michelle Grabowski, University of Minnesota Extension Educator

Cyclamen are popular plants to brighten the home during the winter months. Flowers come in multiple shades of pink, red, lavender and white. When the blooms are spent cyclamen have interesting white patterns on their leaves, varying from an almost complete white horseshoe to regularly spaced white blotches depending on the cultivar. These leaf patterns are normal for cyclamen and make them an interesting foliage plant.

INSV 2 K.Snover-Clift NPDN.jpg

Photo 1: INSV symptoms on cyclamen. Photo by K. Snover-Clift, NPDN .

Patterns that indicate a problem

Gardeners should beware, however, of leaf patterns that occur on some leaves but not others. The natural white color patterns on cyclamen leaves should be fairly consistent on all of the plant's leaves. If you are noticing unusual color patterns on some leaves but not others, this may be a symptom of a common viral infection.

Cyclamen are one of many hosts to the plant virus Impatiens Necrotic Spot Virus (INSV). This virus was first discovered on impatiens plants showing dark colored ring spots on its leaves. Since then it has been discovered that INSV can infect over 300 species of plants. Many flowering house plants, annuals, vegetables and even weeds can be infected with INSV.

The symptoms of INSV vary from plant to plant and even between cultivars. Some plants have random brown dead spots on leaves or streaks on stems. Others are stunted, wilt and die. Many have ring spots on leaves. Cyclamen infected with INSV have random brown spots, often with one or more brown rings around them. In many cases, multiple yellow to brown rings form on infected leaves, looking almost like a fingerprint. These types of ring spots are characteristic of viral infection.

How did my plant get infected?

INSV K.Snover-Clift NPDN.jpg

Photo 2: INSV symptoms on cyclamen. Photo by K. Snover-Clift, NPDN .

INSV is transferred from plant to plant by western flower thrips (Frankliniella occidentalis), a common insect pest found in greenhouses. Thrips larvae that feed on an INSV infected plant pick up the virus. The virus survives within the thrips and the adult thrips are able to transmit the virus to any plant that they feed on for 5-10 minutes. Once infected with INSV, thrips carry the virus with them for the rest of their lives. Infected house plants could have been infected at the time of purchase or thrips carrying the INSV virus could have been brought into the house on the cyclamen or other plant.

What can I do about INSV?
Unfortunately plants infected with INSV can never be cured. They will carry the virus with them for the rest of their lives and can pass it to other plants if western flower thrips are present. Therefore it is best to destroy infected plants to prevent the spread of the disease. Plants infected with INSV can be thrown into the compost pile because the virus will not survive without a live host plant. If thrips are a problem on this or other houseplants, steps should be taken to control them. Many cultural and chemical control strategies are available to manage thrips and can be learned by reading the UMN extension publication 'House Plant Insect Control'. Remember, only thrips that have fed on an INSV infected plants will be able to transmit the virus, so the presence of thrips alone does not mean that plants are infected with INSV.

The best management strategy is to avoid bringing home plants that are infected with INSV or western flower thrips. Before purchasing a cyclamen, inspect both the upper and lower surface of the leaves for unusual yellow to brown spots, especially ring spots. Thrips may be difficult to see without a hand lens since they are only 1/16th of an inch long and very thin. Tapping the leaves of a plant over a white piece of paper can knock off some insects that you will then be able to see moving across the sheet.

Unfortunately plants recently infected with INSV may not show symptoms for a week up to a month. It is therefore possible to purchase a healthy looking infected plant. To avoid future problems, keep the new plant separate from other plants in the house for about 2-3 weeks. This will allow time for symptoms of the virus or thrips feeding to develop without allowing the problem to spread to other house plants.

For more information about general cyclamen care, read the UMN extension publication 'Cyclamen care'.

Cool Plants for the Holidays

Carl Hoffman, University of Minnesota Extension Horticulturist

Be it reasons relating to the economy, an elevated environmental consciousness, or merely a reason to wear a new Snuggie™, we are lowering the temperature in our homes. We can easily compensate for the cool temperatures, but what about our plants? As we enter the holiday season, many of us plant lovers like to use blooming plants to brighten and add seasonal cheer to the interior of our homes. Nearly all of the holiday favorites will perform well for a while, but then will begin to languish. We are fortunate, however, that there are some blooming holiday plants that actually thrive in cool, or even cold, temperatures. Generally, temperatures above freezing, but below 50° F are considered cold, and temperatures between 50° F and 65° F are considered cool. Even some plants, like the poinsettia that prefer warmer temperatures will do quite well in a cooler environment if they are kept from cold drafts and are not overwatered.


Photo 2 - C.Hoffman.jpg

Photo 1: A bench full of solid and bicolor Cyclamens. Carl Hoffman.

There are not many of us that keep our homes below 50° F, but if we did, cyclamens would be happy. The florist cyclamen, Cyclamen persicum, prefers night temperatures of 40° to 50° F and daytime temperatures below 65° F. These plants, with their large backswept petals in colors ranging from pastel pinks and lilacs to deep red and snow white, make beautiful, showy accent plants. The flowers are borne on upright stems that extend above attractive heart-shaped, silver mottled leaves. To prolong the blooming period, select a plant that has only a few flowers open, but many buds.

Cyclamens grow from tubers. They will rot easily if improperly watered so they should be watered from the bottom or, when watered from the top, use care to keep water from the crown of the plant. Allow the surface of the soil to dry slightly before you water, but do not wait until the plant begins to wilt. If placed in a room with cold to cool temperatures, bright light and when watered properly, cyclamen plants can be expected to remain attractive for up to two months.


Thumbnail image for Photo 3Azalea - C.Hoffman_med.jpg

Photo 2: Azaleas in perfect bloom stage for bringing home. Carl Hoffman.

Indoor azaleas (Rhododendron sp) with their masses of double or semi-double flowers in colors including white, pinks, salmons, reds and bicolors make a commanding holiday accent. With optimum temperatures of 45° to 55° F at night and up to 68° F during the day, azaleas will remain attractive for a month or more. When selecting an azalea plant for your home, do not be tempted to purchase a beauty in full bloom, but rather one that has a few flowers open and color showing in most of the buds. Azaleas need to be kept constantly moist and should be watered thoroughly whenever the soil in the pot feels dry to the touch. Azalea plants will drop their leaves if allowed to get too dry or if they are placed in a room with low humidity. For maximum performance, place your azalea where it receives at least four hours of bright, indirect light each day. An indoor azalea in full bloom is truly a living bouquet.


Orchids immediately bring to mind the tropics and warm temperatures, and thus are often overlooked when we are looking for cool temperature plants. However, orchids are an extremely diverse group of plants and there are representatives that will fit nearly every indoor condition, including cool temperatures. Once considered humid greenhouse plants that were difficult to grow under home conditions, there are species that actually require less care than some of our more common indoor plants. Improved breeding techniques have increased their availability and lowered their cost so that we can now readily enjoy these exquisite, long lasting flowers in our homes. Photo 5 - J.Hennek.jpg

Photo 3: Paphiopedilum Satin Smoke.Jayme Hennek, Stearns County Master Gardener

There are at least seven genera of orchids that are classified as cool temperature orchids. Of these, I suggest that you try a Cymbidium or Pahiopedilum orchid for the holidays. A Cymbidium orchid plant in bloom with a huge spray of beautiful waxy flowers will make an outstanding accent or gift. There are both standard and miniature forms of Cymbidiums. Their narrow leaved foliage and large sprays of flowers need room, making the miniatures a better fit in most homes. Paphiopedilum or lady slipper orchids are terrestrial orchids and require less light than many of the other orchids. There are two main groups of Paphiopedilums: those with variegated or mottled leaves which require warmer temperatures, and those with green leaves which require cool growing conditions. Their beautiful flowers with their distinctive pouches may last two months or more under good conditions. Because Paphiopedilums grow naturally on the forest floor, they require a potting medium that contains some peat moss with the bark, and less light than do the Cymbidiums.

Christmas cactus

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Photo 4: Christmas cactus in full bud. Carl Hoffman.

The Christmas cactus (Schlumbergia) is a beautiful plant that enjoys bright indirect light and cool temperatures, particularly when in bloom. Warm temperatures or drafts will cause the flowers and buds to drop prematurely. Purchase a plant that has many buds that are showing color and then place it where it receives bright light without high temperatures. Purchasing a Christmas cactus can be a long time investment as I have seen specimens that have been in families for 30 years or more. Hybrids have been developed that produce flowers in colors ranging from red, pink, magenta, white and even yellow. They are not true cacti, but are epiphytes similar to many bromeliads and orchids. The soil should be kept moist, but allowed to dry slightly between waterings.

Christmas cactus plants can be frustrating because the flowering period is affected by both day length and temperatures and it may be difficult to get them to bloom during the holidays. To initiate flowering, they require short days of less than 12 hours of light and temperatures of less than 68° F. At temperatures of less than 55° F, the buds will form regardless of day length. If your room only drops to 60° or 65° at night, you need to cover the cactus or put it in a dark closet for at least 12 hours each night to trigger blooming. Unfortunately, a plant grown at temperatures above 70° F probably will not flower regardless of the day length.

Norfolk Island Pine

As I was walking through a favorite greenhouse, I decided that I would be remiss if I did not include a non-blooming plant, the Norfolk Island Pine (Araucaria), on my list of cool temperature holiday plants. This conifer with its whorls of flat branches covered with short, dark green needles can be an accent plant even may even serve as a replacement for the family Christmas tree.

Norfolk Island Pine can be a beautiful focal plant in your home if you have a place where it receives bright light for at least part of the day. They will tolerate lower light for a while, but if not returned to bright light, the branches will droop and the new growth will be weak and pale colored. The most common problems Norfolk Island Pine face indoors are browning needles and dropping lower branches. Usually they can be attributed to hot dry air, low humidity, or allowing the soil to dry excessively before watering. Too much fertilizer can also contribute to needle drop and branch loss. It can be difficult to control the humidity in the home, but careful watering will help compensate for low humidity. Keep the soil moist, but not saturated, and water the plant whenever the soil surface feels dry. Like many of our indoor plants, the lower light intensity and the cooler temperatures of winter make it imperative that these plants are not overwatered.

We can readily see that a home with cool room temperatures need not be a home without blooming plants during the holidays. Well known favorites like cyclamens, azaleas and the long time favorite Christmas cactus welcome the cooler temperatures as do some of the newcomers like orchids. Of course, we can always add the "enjoy and toss" plants like poinsettias, hydrangeas and mums for more temporary bursts of color.

For more information on growing these or any other indoor plants go to


David C. Zlesak, University of Minnesota Extension Educator

Taking plants from the relatively low light and moderated temperatures of the home environment and plunging them suddenly outdoors in bright sunlight, wind, and temperature extremes can result in severe injury. Depending on the extent of the injury the plant may be capable of recovering relatively quickly, after multiple weeks, or in extreme cases not at all.  As plants grew indoors, the tissues that they produced were adapted to those environmental conditions.  With a gentle transition period, plant tissue can adapt to some degree when conditions change.

Plants use environmental cues to help them adapt their tissues to their current growing conditions.  For instance, leaves produced in shade typically have more surface area and are thinner in order to better intercept light and best invest energy resources into the most efficient type of tissue.  Leaves grown under brighter light are often thicker with additional layers of photosynthetic cells within them and have a more developed waxy cuticle layer in order to better conserve moisture.  Higher light levels are often associated with greater heat and therefore a greater potential for water loss. Leaves grown under higher light conditions also are typically higher in pigments like carotenoids and anthocyanins that serve in part to defend leaves from damage from excessive light, especially UV light.

Tracy Walsh
Preview Event is Feb. 12; Exhibit Opens Feb. 13

art4-1_600px.jpgChaska, Minn. (Jan. 8, 2008) – Escape the icy blasts of winter and feast your eyes on some exquisite tropical beauties at the Minnesota Landscape Arboretum’s “Totally Orchids – Delight at First Sight” exhibit, opening Friday, Feb. 13, in the Arboretum’s Oswald Visitor Center.

Garden Calendar for February

David C. Zlesak


Photo 1: With increasing light levels, houseplants can use more nutrition. David Zlesak

Continue to the planning process for your 2009 garden. As you decide the plant materials you would like to have this season consider how you will obtain these plants. Some may not be readily available and you will need to start them from seed soon or orders should placed soon for seed and nursery stock to help ensure you get what you want. Many catalog suppliers have discounts or other incentives for those that order early.

The Moth Orchid Takes Off!

Christopher Currey University of Minnesota Graduate Student

Moth orchids (genus Phalaenopsis) have been taking the potted plant world by storm for the last decade. They are now second only in total sale value to poinsettias, yet per pot they are the most valuable crop on the market today. The advent of advanced tissue culture and production methods has brought the plant out of the elite Victorian glasshouse to the shelves of nearly every retailer, allowing them to become the most accessible orchid on the market today. Combine this accessibility with their ease of growing in the home environment and you have a wonderful, rewarding tropical orchid for the everyday home gardener.

Winter Carnival Orchid Show


Escape to the Tropics January 24 & 25, 2009

During the Saint Paul Winter Carnival, winter and all it's glory, snow, ice and frigid temperatures, are celebrated. One event stands out and gives attendees a way to escape to the tropics without even getting on a plane, the Winter Carnival Orchid Show at the Marjorie McNeely Conservatory January 24 and 25.

Unexpected Insect on Houseplant

Jeffrey Hahn, Asst. Extension Entomologist


Photo 1: Tobacco budworm. Jeff Hahn

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