Polka Dots Are Back

Paphiopedilum bellatulum in the Fuqua Orchid Center

Of course they are. The slipper orchids in the Fuqua Orchid Center were rocking the dots weeks before polka dots made a big splash at September Fashion Week in New York.

Scary spotted slippers in London. Photo by Mark Leibowitz

Paphiopedilum bellatulum (top) scores extra points with us for having gorgeous spotted flowers and leaves. We love the downy texture of the flowers and flower spike. It grows natively in the crevices of limestone outcrops in Myanmar, Thailand and southwest China. 

Autumn is a great time to see a cool-weather flush of flowers on the slipper orchids (with and without spots) in the Orchid Display House and the Tropical High Elevation House.

Coryanthes, you make me crazy.

The fabulous but frustrating Bucket Orchid (Coryanthes)

Coryanthes are the most difficult plants I have ever grown. Clearly they are worth the effort--a fragrance that is almost edible, a grotesque (and let's face it, slightly pervy) appearance, a clever pollination mechanism, a symbiotic relation with two species of ants. But absolutely maddening in cultivation, at least in our greenhouses. The plants grow robustly for a year or so before I start to notice the subtle signs of decline: no new shoots appear, a few leaves are shed, and finally, the entire plant is leafless. If I remove the plant from its pot the root system is dead. Coryanthes make me want to bang my head against the wall.

Why? Coryanthes must be the orchid world's biggest mollusk magnets. While the adjacent pots of Phalaenopsis remain mollusk-free, it's rare to find a Coryanthes pot in any of our greenhouses that doesn't harbor at least a couple of slugs, and even worse, their minute evil cousins, the bush snails. Forget the metaldehyde, iron phosphate, beer, copper strips. It seems nothing kills these guys except the bottom of my shoe. And I have actually learned to enjoy crushing bush snails between my thumb and forefinger.

So, this summer I have applied a draconian solution--removing all the organic medium surrounding the roots and attaching our Coryanthes, young and old, to slatted cedar slabs as the new roots emerge. This is indeed a radical step since Coryanthes love moisture, plus it flies in the face of conventional wisdom which recommends mimicking an ant garden stuffed with acidic organic matter. But on these slabs the slugs & snails have nowhere to hide. And the mild but regular drying will make the Coryanthes a less appealing refuge for egg laying. That said, it's still a very humid greenhouse.

Look at those gorgeous root tips! Completely unmolested by slugs.

If the slabs look familiar to you it's because they are in fact simply the bottom of the classic cedar hanging basket sold by the major orchid supply houses. I think most people hang these slabs vertically, but I have decided to use them as rafts in order to retain a bit more moisture around the Coryanthes roots.

Time will tell whether or not this is a good cultural approach for Coryanthes.

Where do I cut my Dendrobium after it blooms?

Wondering where to cut your Dendrobium orchid spike after it flowers? You are not alone!  We get lots of questions about Dendrobium spikes. Dendrobiums are very diverse anatomically and I suspect many folks simply aren't sure where the spike ends and the stem begins. So I am going to show you two common types of Dendrobium and where to cut their spikes. It's pretty simple.

Look familiar? The most common type of Dendrobium available commercially are the myriad colored hybrids that have Dendrobium phalaenopsis in their pedigree. They have erect stems ranging from one to two and a half feet tall. Their leaves are carried on the upper half of the stem.

The Dendrobium pictured above is ready to have its spike removed. Notice that the flower spike originates near the apex of the stem just above the last leaf. The spike itself has no leaves or bracts.

After your Dendrobium has finished flowering remove as much of the spike as possible without cutting into the leafy stem. Check my earlier post for more about cutting tools.

Old stems will not flower a second time, but DON'T remove them, at least not yet. Your plant needs them. A strong plant consists of minimum of three mature stems. The best time to remove surplus stems--typically the oldest stems that are leafless and yellowing--is when you are repotting. Once the plant is unpotted you can easily cut the horizontal rhizome that connects the upright stems and remove the portion with shriveled stems.

I love the Dendrobium nobile hybrids like Dendrobium Red Emperor 'Prince' (above) --they are some of my favorites for using in our annual Orchid DAze display; and I'm pleased to see that they are becoming more popular and more common in the retail market. You may have bought one last year at our Gently Used Plant Sale.

Notice that the Dendrobium nobile flowers are not carried on a single tall spike. Instead they are produced on short spikes of two to four flowers that appear at each node along the stem. It's easier to see the short spikes after the flowers have fallen (below).

The short spikes turn an unsightly brown (see above) after the flowers have fallen, so I like to remove them with a razor blade, cutting as close to the stem as is reasonably possible.

Dendrobium nobile and its hybrids are a bit trickier to grow than their cousins, the Dendrobium phalaenopsis hybrids--but they are SO worth it! Check here for How to Grow Dendrobium nobile.

Wondering where to cut your Phalaenopsis spike? Find out here.
click here to find out where to cut your Cattleya spike.
To find out where to cut your Oncidium spike, click here.

Where do I cut my Cattleya after it blooms?

I'm glad you asked! It's important to know where to cut your Cattleya spike after it flowers. Cattleya anatomy is a little quirky and it is easy to make a mistake. The good news is that there's really just one bit that requires an introduction--the bud sheath. Once you are able to recognize a bud sheath, deadheading a Cattleya or its close relative Laelia is a snap.

So grab your favorite cutting tool and follow along!

1. Locate the bud sheath. Have a look at the photo above. Both flowers are supported by a vertical spike. The upper part of the vertical spike is visible emerging from the top of a green bud sheath.  The sheath is sealed on two sides and open at the top. The lower part of the spike is faintly visible in silhouette through the backlit bud sheath.

The purpose of the bud sheath is to protect the young flower buds as they develop. It remains in place even after the flowers are spent. Bud sheaths are green or papery brown. Cattleyas and laelias are stealth bloomers--in many species the bud sheaths appear months before blooming, with the buds emerging just a week or so before opening. The flowers often take me by surprise.

2. Look carefully! If no flowers or old spikes are visible, carefully examine the bud sheath to make sure that it is an old sheath. You don't want to accidentally remove a sheath full of young buds.  Gently squeeze the sheath to make sure that there are no buds inside. The color of the sheath is not a reliable indicator. Some orchids, like the Laelia pictured above and below, have sheaths that remain green after the flowers are spent. Others produce bud sheaths that turn papery brown while the buds are still developing inside.

Each mature shoot--the pseudobulb, leaf and bud sheath--produces just one flush of flowers during its lifetime.  If you can still see the old spike with its spent flowers you needn't look for a second flush of buds inside the sheath. The show is over. It's time to remove the spike and sheath.

3. Find the spot where the bud sheath meets the stem. The bud sheath and its flower spike originate at the top of the stem (pseudobulb) and they are surrounded by one or two leaves.

4. Position your cut as close as possible to the base of the leaf. 

5. Make the cut through the sheath and spike.

6. Examine your plant for more old sheaths. Any pseudobulb that matured recently could have a sheath. You can use the same cutting tool to remove all the old sheaths on that plant. That's it! Don't forget to safely discard or clean your cutting tool before cutting another plant.

Why is it important to remove old sheaths?

Prompt deadheading of cattleyas and laelias is a high priority in our greenhouses. Old bud sheaths often fill with water and bacteria, becoming bags of icky aqueous goo. You can get away with being lazy about deadheading your Oncidium, but not your Cattleya.

Wondering where to cut your Dendrobium? Find out here.
Click here to find out where to cut your Oncidium spike.
Go here to learn where to cut a Phalaenopsis spike.