Plant Palette

Plant Palette

Hoya

Photo of Jennifer Schultz Nelson

Jennifer Schultz Nelson
Extension Educator, Horticulture
jaschult@illinois.edu

I've always been a big fan of flowering plants for indoors, but all too often these plants require a level of care that I cannot provide consistently. That doesn't stop me from buying them of course, having convinced myself that I will certainly find the time to provide them the proper care they need. Then reality strikes, and I am busy beyond belief and I forget to water my plants. Or I forget to fertilize them. More often than not I forget both. I'm left with dead or dying plants and essentially money wasted.

I've written about a number of "indestructible" houseplants this year that tolerate neglect quite well. These plants combine extremely well with a busy schedule.

For me the ultimate in indestructible houseplants are ones that flower. The most spectacular example that I have had success with is blooming in my kitchen as I write this—a gorgeous orange-flowered Clivia. This plant requires that you not water it all winter long in order to have blooms in the spring. How perfect! It actually needs me to forget about it for awhile. That I can handle!

Another plant that I have recently purchased because of both its reputation of being indestructible and having flowers is the Hoya. There are actually two to three hundred different species of Hoya found in the world, native to tropical Asia, Australia and Polynesia. Many of them are cultivated as houseplants in more temperate parts of the world. Hoya carnosa, which produces porcelain-like light pink flowers, is probably the most common species grown as a houseplant.

Hoya are either shrub-like or vining, with succulent shiny or hairy leaves. Looking at their leaves, it's easy to see how they earned their common name wax plant. Each leaf is perfectly formed, as if sculpted from wax. Leaves vary widely in size, but typically come to a point, and may be wrinkled or variegated.

Like most indestructible houseplants, Hoyas will tolerate low levels of light indoors. Also like most indestructible houseplants, tolerating low light does not equal thriving in low light. Without appropriate lighting, a Hoya will be a nice green vine indoors, but will not grow very fast, and will probably never flower. A healthy looking green plant is a great addition indoors, but in my opinion flowers would be even better.

Once you see the gorgeous flowers that Hoyas are capable of producing, you may reconsider settling for just a green plant. The flowers are borne in clusters called umbels. Each flower is on a small stalk radiating from a common point, much like an umbrella. The one feature that all Hoya flowers have in common is that they are all shaped like five-pointed stars.

Hoya flowers come in all shapes and sizes. Individual flowers may be only four to five millimeters in diameter, to well over three inches. Depending on the species, umbels of flowers may contain only one flower, to over fifty.

Just like the leaves, Hoya flowers may be shiny or hairy. Colors range from white, to pink, purple and brown. A true red Hoya is rare, but breeders are getting closer and closer to this goal. Blue flowers are not found in the Hoya genus.

Bright indirect light and age of the plant appear to be key elements in getting Hoyas to bloom. Sources quote that a plant needs to reach a minimum age in order to bloom. This is probably not so much about age per se as it is about size of the plant, and how rootbound it is in its pot. Many sources recommend infrequent repotting of Hoyas. Most likely this means that constricted roots are a stress on the plant that helps trigger it to flower. Bright indirect light is another trigger. Fertilizing with a balanced fertilizer during active growth may also help induce flowering.

After Hoyas are finished blooming, it's important to resist the urge to remove the spent blooms. These should be left intact, as new blooms will emerge from that same location year after year. Some people find that the scent of Hoya flowers is too strong and overpowering for indoors, and so move their plants outside when in bloom if possible.

Proper watering is essential for Hoyas. They need to dry out completely between watering. In winter, this means a lot of time will pass between watering. Expect to water more frequently in spring and summer, which is also their period of active growth.

I currently own two small specimens of Hoya. They were not labeled with specific cultivar names, so my best guess is one is a variegated cultivar of Hoya carnosa, which has shiny oval-shaped leaves, and some cultivar of Hoya compacta, which has twisted leaves that hang down and resemble ropes. One common name for this Hoya is Hindu Rope Plant. Neither has flowered yet, but I have the perfect space for them on my north-facing front porch this summer. So hopefully this year they will get a little closer to flowering. In the meantime they sure are nice looking plants that don't mind being neglected now and then.

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