Obsessing Over Orchids

Confession time.  I am more than a little obsessed with orchids. Why not?  They are drop-dead gorgeous, the Grace Kelly of floral displays. Here’s their dirty little secret: some can be deceptively easy to grow. Phalaenopsis (fayl-eh-nop-sis) are the easiest to grow.  Also called moth orchids, their round faces float above arched stems making them the darlings of home décor magazines.   

Close-up photo of the flower petals of the Phalaenopsis orchid, also known as the moth orchid.
Phalaenopsis (moth orchid). Photo credit: UME-HGIC

And they are ever so undemanding. Just give them bright indirect light, very little water and a room with normal temperatures and they will be quite happy.  Honest. Plus – drumroll, please – Phalaenopsis orchids bloom for two to three months starting right about now.  Yes, that long. 

I have a gaggle of orchid gals lined up on a table in my office, many of whom I’ve had for years.  Last year’s birthday orchid (thanks, Dusty) bloomed off and on for six months. Just.  Don’t. Overwater.  That’s the primary cause of their demise.  All they need is a gentle weekly spray of water in the sink. A tablespoon or two of water a week will do. Why?  They are epiphytes. In the wild, they attach themselves to tree trunks and absorb the moisture and dissolved nutrients running down the bark during rain. They’re adapted to drying out in between rains because the root velamen acts like a sponge and holds moisture for a time.   Those dangling “legs” growing up, down, and around are aerial roots.  That’s what you spray.  

In the wild, orchids drape themselves over tree bark and branches.  They don’t need soil.  The orchids we buy are in a special chunky bark potting mix that offers support and holds a bit of moisture. It’s okay to moisten that mix a bit and let it drain to boost the humidity.  It’s also okay to add a bit of specialized orchid fertilizer to boost your orchid’s health and bloom time. Do you need a special orchid pot with decorative holes? Nope.  But it does look kinda cool when those roots come rambling out aka Audrey in Little Shop of Horrors.  

Two types of the Phalaenopsis orchid, also known as the moth orchid. One orchid has alternating flower petals that are light green and light maroon in color. Each petal has faint green veins. The other orchid has white petals with small maroon dots.
Phalaenopsis varieties. Photo credit: Marcia Toder, UME Master Gardener- Washington Co.

The most challenging thing about Phalaenopsis orchids is deciding which one to try.  Petite or full-size?  Fiery magenta, buttery yellow, or pure white?  With or without contrasting veins, sepals, or spots? Stroll through any orchid display, and you’ll soon wear a slap-happy grin.  Stay focused by looking for solid, deep green leaves, robust aerial roots, perky blooms, and many buds to maximize bloom time. Where should you look? Garden centers often have handsome plants, but I’ve found quite nice specimens at home improvement and grocery stores.  

Once hooked, you might venture into other orchids such as Dendrobium, Cymbidium, Cattleya, or Lady Slippers.  Forms vary from 6-inch ruffled blooms to cascades of tiny stars.  And oh, the fragrances. Be dazzled by all the myriad colors and forms of orchids by visiting a public garden exhibit.  Two outstanding collections are a day trip away. The U.S. Botanic Garden in D.C. has an annual orchid show, “Orchids: Masters of Deception,” from February 14 to April 27.  And world-class Longwood Gardens offers an immersive experience with a floor-to-ceiling orchid display in their conservatory.

It’s easy to go overboard on orchids.  And yes, there are support groups.  The American Orchid Society’s website is a good place to learn more, as is our webpage. So, be bold. Try an orchid. It may become a delightful new obsession.

By Annette Cormany, Principal Agent Associate and Master Gardener Coordinator, Washington County, University of Maryland Extension.

This article was previously published by Herald-Mail Media. Read more by Annette.

Q&A: Are These Red Leaves Too Stressed?

Photo of several plants in a terrarium. The focus of the photo is a plant with oval leaves that are red with white veins. This plant is Dischidia ovata, commonly called watermelon dischidia or hoya.
Photo credit:  Miri Talabac
Photo caption:  Dischidia ovata in a terrarium under intense light.

Q:  I have a Hoya whose leaves have turned quite red. While pretty, I want to make sure I’m not stressing the plant too much. How can I tell?

A:  If growth is progressing normally and there aren’t any other concerning symptoms (like leaf drop beyond the typical shedding of old leaves, or stunted growth), then I would say you’re at a tolerable level of stress for the plant. Reddening foliage is sometimes referred to as “sun stress” by houseplant growers, and it’s the plant’s natural response to intense light by generating sunscreen pigments to protect the leaf tissues.

Some species or cultivars of Hoya and their Dischidia cousins can turn ruby-red or rose-blushed if grown in bright light. I’ve grown cuttings propagated from a single Watermelon Dischidia, Dischidia ovata, in different light levels, and some will stay green in lower light and others turn varying degrees of red in higher light. In one case, under a bright spotlight over a terrarium, the plant turned completely ruby on every surface exposed to light. Even across a single leaf, areas in shadow can remain green while the rest blush red, as they did when I peeked beneath one leaf that was partially covered by another.

I have a ‘Sunrise’ cultivar of Hoya in a pot hanging underneath the edge of LED grow lights. The half of the plant growing close to the lights is red, and the half receiving much less light on that outer half is green. If anything, I’d say that the redder side grows more vigorously.

Other houseplants can also redden if grown at the higher end of their light level preferences, such as certain begonias and bromeliads. In other cases, over-lit foliage bleaches to a paler or yellower color, so not every indoor plant can adapt to stronger light.

Sometimes you just might need to experiment to see how a plant reacts, and keep in mind that other factors (nutrient availability, soil moisture level, ambient temperature and humidity) which might be causing plant stress can complicate your assessment of how a plant is faring based on light level.

By Miri Talabac, Horticulturist, University of Maryland Extension Home & Garden Information Center. Miri writes the Garden Q&A for The Baltimore Sun and Washington Gardener Magazine. Read more by Miri.

Have a plant or insect question? The University of Maryland Extension has answers! Send your questions and photos to Ask ExtensionOur horticulturists are available to answer your questions online, year-round.

Proper Care Extends the Beauty of Holiday Plants

red poinsettia plants
Well-kept poinsettias can bloom for up to 8 weeks.

Poinsettias and amaryllis and paperwhites, oh my. These holiday beauties add grace to our homes but need proper care to keep up their show. 

Caring for Poinsettias

Poinsettias are the divas of holiday decor. Their colorful bracts – modified leaves that change color – deliver an instant “wow” factor. But like all divas, they can be challenging.  

They like bright, not direct, light and prefer daytime temps between 60 and 70 degrees and nighttime temps in the mid-fifties. They hate drafts, so keep them away from heat vents, fireplaces, doors, and windows.   

Water them only when the soil is dry. Let the water run through the bottom of the pot. Good drainage is crucial.  

Foil wraps are pretty but problematic. So poke a hole in the foil for drainage and set your poinsettias on a pretty plate or tray. A well-kept poinsettia will bloom for six to eight weeks.  

I toss my poinsettias at the end of the season (cue the gasps), but determined, thrifty, or thrill-seeking gardeners keep them going from year to year. Here’s how it’s done.

Cut back your poinsettias in early May to 3 inches and repot them into a soilless potting mix. 

Move them outdoors after all danger of frost has passed, usually mid-May. Start them out in the shade and introduce more sun over several weeks. When the new growth is 2 inches tall, start fertilizing every month.  

Pinch or prune out the tips of branches when the new growth reaches 4 inches and again after the new growth reaches 2 or 3 inches. Stop pinching in early September.

Bring your poinsettias inside in late September before the nighttime temperatures dip below 60 degrees. Cut back on fertilizer and put the plants in bright light.  

Now comes the fun part.  

Poinsettias need a period of darkness since shorter days trigger their “flowering.” So, put yours in a dark closet or box for at least 14 hours every day until Thanksgiving. 5:00 p.m. to 7:00 a.m. works well.   

Next, bring your poinsettias back into full-time light and get ready to enjoy another show.  

Caring for Paperwhites

Another holiday favorite, paperwhites deliver a sweet perfume from dozens of white shooting star-like blooms for a month or two. 

If you received paperwhite bulbs as a gift, choose a shallow pot for forcing them into bloom. Put an inch of sterile potting mix or gravel in the pot. They grow well in both. 

Tuck the bulbs in tight, pointed ends up. Add soil or gravel until half the bulbs are covered. Water thoroughly and often to keep the bulbs moist.  

Put them in a cool, well-lit room until the shoots are an inch tall. Then move them to a warmer spot.  If their stems topple, support them with thin stakes or chopsticks tied with raffia or ribbon.  

Paperwhites bloom only once, so toss the bulbs after you’ve enjoyed their show. Sorry, no encores.

Amaryllis

Amaryllis is another holiday bulb that delivers drama. For tips on planting and care, snag our fact sheet.

red and white amaryllis flowers
Amaryllis delivers drama with clusters of colorful flowers up to 6 inches across. 

Enjoy all your holiday plants and time spent with friends and family in this most special time of year.   

By Annette Cormany, Principal Agent Associate and Master Gardener Coordinator, Washington County, University of Maryland Extension.

This article was previously published by Herald-Mail Media. Read more by Annette.

Q&A: What Causes Aloe Leaves to Turn Yellow?

potted aloe vera plant
Aloe vera plants.

Q:  I have an aloe indoors that is developing some yellow leaves. Do I need to feed it or change something else about how I take care of it?

A:  Leaf yellowing is a difficult symptom to trace back to a particular issue since in general it can be caused by overwatering, under-watering, under-fertilization, too little light, too much light, pest feeding, and a few other factors. With indoor succulents, too much light is a rare problem, and accidental over-watering is relatively common, which is why I presume low light and soil moisture are the conditions needing evaluation first.

A leaf that turns yellow is one a plant is probably about to shed, so even if the original issue is resolved, be aware that it won’t usually green up again. That’s okay, as long as the shedding isn’t excessive (and if it is, it might be too late to fix); plants can reabsorb some of the resources stored in the leaf before it dies and falls. It’s also perfectly normal for any plant to shed its oldest leaves from time to time since they have limited usefulness to the plant as they age or succumb to cumulative injuries or stresses.

Succulents like aloe thrive in bright light while indoors, so it’s possible yellowing has begun because the plant is running low on stored energy that has allowed it to tolerate insufficient light so far. (Plants make their food from light, so while occasional fertilization can supplement their nutrition, it’s not a substitute for receiving enough light.) While indoors, aloe grows best where it gets either several hours of direct sunlight close to a window or is placed under plant grow lights that can supplement or replace natural light (if window light is insufficient).

Succulent roots should get fairly dry between waterings, though each watering still needs to be thorough so all of the potting mix is well-moistened each time to eliminate dry pockets. Extra water should freely drip out of the bottom drain holes of the pot. Feel the soil about an inch deep (or more, depending on pot size) and only water when it’s become pretty dry to the touch at that depth. Be sure to empty any drained water in a saucer promptly so the pot doesn’t sit in water, as this can kill roots. Root rot can result in leaf yellowing because there are not enough healthy roots left to support all of the plant’s foliage. As with other triggers for shedding, the oldest, lower leaves are usually sacrificed first.

If you haven’t fertilized the plant in several months, it might benefit from a light dose. Normally indoor plants don’t need fertilization during the fall through winter, but if a plant has been nutrient-deprived for a while, it may benefit from replenishing those nutrients in the soil. The precise fertilizer formulation doesn’t matter much in this case, though nitrogen is likely the nutrient of greatest importance (the N in N-P-K ratios) for overall plant health and leaf color, so it can be chosen as the highest number of the three (such as 3-1-2 or 10-5-5 as arbitrary examples). Regardless of the type of fertilizer chosen, follow package instructions about how to dose it. You’d probably only need one dose (maybe at most two) to last the plant through the winter since it won’t exhaust those nutrients quickly. If you suspect scale, mealybugs, thrips, or mites are causing damage, get them under control first, since you don’t want to feed the pests extra nutrients with the fertilization.

Indoor plants grow slowly (if at all) in winter, and succulents tend to be slow growers in general, so it may take some time for the aloe to show any improvement, which is fine as long as it isn’t declining further in the meantime.

By Miri Talabac, Horticulturist, University of Maryland Extension Home & Garden Information Center. Miri writes the Garden Q&A for The Baltimore Sun and Washington Gardener Magazine. Read more by Miri.

Have a plant or insect question? The University of Maryland Extension has answers! Send your questions and photos to Ask ExtensionOur horticulturists are available to answer your questions online, year-round.

Celebrate a Gardener’s Holiday

Amaryllis (Hippeastrum sp.) is a pleasure to watch unfold.

Celebrate your green thumb this holiday season with everything from décor to gifts.

Bring the garden indoors with plants, plants, and more plants. Start some amaryllis bulbs or paperwhites. Bank poinsettias in a bay window. 

Top a delicate cyclamen with a gardening cloche or delight in the blooms of a Christmas cactus or orchid. These plants will add beauty and satisfy your need to play in the dirt.

Moth orchid (Phalaenopsis sp.). Photo: Pixabay

To keep your plants lush and lovely throughout the holiday season, check out the care tips in our Home and Garden Information Center fact sheets. Here are a few to get you started:

Go natural for decorations. Snip some holly or evergreen boughs and stuff them in baskets and pots. Add some winterberry or curly willow branches for flair. Fill a pottery bowl with pinecones.  

Native winterberry jazzes up holiday arrangements.
Photo: M. Talabac

Jazz up outside containers with evergreens and colorful branches for some welcoming eye candy.  

Weave yarrow, baby’s breath, statice, hydrangea blossoms, and other dried flowers into wreaths, swags, and arrangements. Stuff an antique pitcher with an armful of Lunaria’s silvery seed pods.  

Take a walk through a meadow with your clippers and a big basket and discover an abundance of interesting grasses, seed pods, and natural forms to enhance your holiday decorating.  

Leave them natural or dust them lightly with a bit of gold or silver spray paint for a bit of holiday sparkle.  

Next, add a few purchased decorations that mirror your passion for gardening. Tie tiny copper watering can ornaments onto your tree. Use zinc or copper plant markers as gift tags.  

And just for fun, decorate a child’s holiday tree with brightly colored kids’ gardening gloves and tools you can later donate to a school garden.

Gifts for gardeners are a breeze. Give hand-softening soaps and lotions. Wrap a bunch of fresh holly in festive tissue. Pot an amaryllis bulb or other plant in a handsome pot.  

Look for classic garden jewelry with blossoms cast in silver or gold. Or give a gift from your garden such as homemade pesto, a rooted houseplant cutting, or seeds collected from a favorite plant.   

Are you crafty? Indulge your artistic side to create homemade gifts with a gardener’s touch. 

Lavender sachets made from homegrown lavender make lovely gifts. 

I give friends tins filled with lavender cookies made with lavender from my garden. I delight in friends’ gifts of hand-stitched sachets, dried flower bunches, and potted herbs.  

I can hear the guys out there saying, “Enough with the girly stuff, whatcha got for me?” Tools, dudes.  And yes, we gals like tools, too. 

Check out your local garden centers, then hit the catalogs. Two of my favorites are Lee Valley and Gardener’s Supply. Both have quality tools and other garden gear.  

And in my book, you simply cannot go wrong with a gardening book. New or used, your favorite reads and references will help to grow your gardening friends’ libraries and know-how. 

Whether yours is a homemade or store-bought holiday, make your home and gifts a beautiful reflection of your passion for gardening.  

By Annette Cormany, Principal Agent Associate and Master Gardener Coordinator, Washington County, University of Maryland Extension.

This article was previously published by Herald-Mail Media. Read more by Annette.

Fine-tuning your indoor plant lighting choices

This is the final article in our four-part series about indoor plant lighting. You can also read the first, second, and third articles.

You may see two other details provided in lamp specifications aside from the terms introduced in my last installment. They are not critical factors but can influence your satisfaction with how the lights look by themselves, and how plants, decorative pots, and other objects look underneath them.

The appearance of plants under the lights is not only important for aesthetics, like seeing the true colors of blooms, but also for detecting leaf discoloration, which can be a key symptom of malnutrition, light stress, or pest or disease damage.

Color Rendering Index (CRI)

While this doesn’t affect actual light intensity, it does impact our perception of how colors will look under a light and is a matter of personal preference.

On a scale of 0 to 100, the higher the CRI value a lamp has, the more accurate the colors will look compared to viewing in natural light. At the low end of the scale, colors are lackluster (desaturated) and less distinguishable from each other. Since incandescent, fluorescent, and LED lights all produce light by different means, they have different CRI ranges, though improvements in technology are closing this gap. Ideal ratings are in the 80s and above, with the 90s considered “high CRI.”

Continue reading

Indoor lighting options: terms, types, and measurements

terrarium plants under LED lights
Terrarium under LED lights. Photo: M. Talabac

This is the third in our four-part series of articles about indoor lighting for plants. You can also read the first, second, and fourth articles.

Artificial light sources come in several forms, all relatively easy to acquire. Costs can vary wildly, and some are more electrically efficient than others. The variety of available options allows you to customize setups to your needs and the preferences of your plants. Before you dive into an overwhelming list of web search results, here are traits of the basic categories:

Light-Emitting Diode (LED)

  • best energy-efficiency in terms of light produced per watt consumed (especially if the light has the ideal spectrum)
  • coolest to the touch except for high-powered units, which usually have small built-in cooling fans
  • can be expensive for high-quality fixtures, though costs are decreasing
  • light output does not dim significantly over time, though diodes do have a finite lifespan
  • reach full brightness immediately or very quickly when turned on
  • diodes can either be exposed or under a frosted or textured cover to help diffuse the light
  • diodes are directional, meaning they don’t emit light in every direction the way a fluorescent tube does, so reflectors aren’t usually needed
  • more even light output from one edge of the fixture to the other
  • can be round like a spotlight (with a cluster of diodes) or straight strips (or strips inside a tube) with one or more rows of diodes
  • some replacement “tubes” can be used in place of fluorescent tubes in a fluorescent fixture, but you must check with the fixture’s manufacturer for compatibility as mixing components is a matter of electrical safety
terrarium LED spotlights
Terrarium LED spotlights. Photo: M. Talabac
LED panel lights
LED panel. Photo: M. Talabac