Hoyas in Your Home: A Growing Obsession

Over the years, we've seen some trends in houseplants come and go here at Specialty Tropicals. Often, interest in certain categories is spurred by new species or varieties being made available to the mass market through tissue culture, which allows growers to take a small piece of tissue from a rare plant and create hundreds or even thousands of clones, all with identical genetics. Full disclosure--we were never really "Hoya people", until our customers began requesting tons of them, and now we're hooked, too!

With amazing variety, beautiful (and sometimes bizarre) foliage, and blooms as pretty and fragrant as any orchid, Hoyas are an easy-to-grow fascination for many indoor gardeners today. Learn how to grow great Hoyas at home, with. few simple steps!

The Hoya Backstory

If you're not already familiar with them, Hoyas are a huge genus of highly variable plants, mostly vines, in the family Apocyanaceae, which also includes plants like the common Milkweed that blooms in our pasture outside the greenhouses and attracts butterflies and their caterpillars. Included in the same family are familiar house- and garden plants like Oleander, Periwinkle, and a wide range of vines, succulents, shrubs, and even full-sized trees!

Though quite a few of their relatives in the Milkweed family produce potent toxins, Hoyas are happily considered completely harmless to humans and pets!

In the wild, Hoyas occur in tropical and subtropical parts of Asia, Australia, and Polynesia.

Most are vining plants that grow as epiphytes (attached to tree trunks) or

One consistent feature of Hoyas is that they bloom from a peduncle, a structure that forms at a node or stem-tip (a node is where a leaf or branch is attached to the main stem), and the same peduncle flowers over and over, so never remove those after the blossoms fall! Hoya blossoms are in the form of an open umbrella, with a convex curved shape, composed of a group of individual flowers. Each blossoms has three basic parts, which generally create a star or other geometric shape.

Hoya blossoms are often sweetly fragrant, usually more so after dark!

Some Hoya species bloom more freely than others, and while the flowers are a prized gift from your Hoya plants, their foliage can be equally fascinating, and it on display every single day for your enjoyment!

Caring for Hoyas - A Guide to Superior Growth & Beauty

Once you know the basics, Hoya care is surprisingly simple. Here are the essential elements

of our recipe for beautiful, healthy Hoya plants:

1. Potting

   Hoyas do well in standard plastic pots, provided they have adequate drainage. We don't like pots with attached saucers, because it's essential that they have excellent drainage. If you do have a pot with a saucer, or use one to prevent damage to surfaces, just make sure that any excess water that drains through is emptied promptly, within an hour or so after watering. Never use pots that don't have adequate drainage holes in the bottom, because wet roots spell doom for your Hoyas! When it comes to potting medium, Hoyas want a soil that allows for ample drainage and air circulation around the root system. Remember, most of them naturally grow clinging to tree trunks, rocks, and other other surfaces, where their roots are exposed to the air and water has ample opportunity to drain away. Our recipe for a perfect Hoya medium includes "chunky" elements like fir bark (use orchid-grade bark, not backyard mulch), perlite, pumice or coco coir chunks. Beyond that, Hoyas enjoy a medium with organic content like peat or wood fiber-peat combination. We suggest the following blend for starters: Peat or Peat-Wood Fiber Blend 1 Part Chunky perlite or pumice 1 Part Slow-Release Fertilizer (2-1-2 formula). 1 Tablespoon per Quart Soil pH for Hoyas needs to lean toward the acid side (5.5-6.5) for some species, to neutral (7.0) for others. Using a peat-based medium typically yields a finished soil with a pH of around 6.0 - 6.5, which is ideal for almost all Hoyas.

   
   

2. Watering

   As a general rule of thumb, we find that Hoyas enjoy a good, deep watering on a less frequent basis, rather than shallow waterings more often. We top-water Hoyas in both our production and retail greenhouses, because they seem to appreciate the water on their leaves, and top-watering helps flush mineral salts that may accumulate on the soil surface if you're using an unfiltered home water source. With each watering, wet the soil until water is flowing from the drainage holes at the bottom, then allow the pot to drain well in a sink or saucer, making sure that no water remains in the saucer an hour after watering. Allow the soil surface to dry well between waterings. A good gauge is to gently dig your pinkie finger into the soil and water when the soil feels dry at least an inch deep in the pot. Hoya leaves are succulent, storing some water to sustain the plant through dry spells, so they can survive a little under-watering on occasion. On the other hand, air circulation around the roots is essential if they're going to survive longterm, and root rot is a common cause of failure with beginning Hoya growers. At Specialty Tropicals, all our plants are raised with reverse-osmosis filtered natural water, but some homes may have enough mineral content in the water supply to require filtration or bottled water for your plants. If you see white crust accumulating on the soil surface, that's a sign that your water is too mineral-rich and may need to be filtered for your plants' safety.
   

3. Humidity

   Hoyas are tropical and tend to grow in close quarters with other plants, which means they like their environment a bit on the humid side. At a minimum, 40% humidity, which is about the natural level in most homes, is needed for good growth, but they will enjoy a boost up to about 60%, and a few specific species enjoy even more. To increase your plants' humidity without a terrarium or mist system, the simple solution is a pebble tray. Use any waterproof container like a plastic shoebox, saucer, drain pan, pie plate, or whatever you like that is wide enough to extend beyond the leafspan of your plants. In the bottom of the container, place a layer of pebbles, marbles, glass beads, or other inert material at least one inch deep. Add water to just below the surface of this layer, then place your plants on top, so that the bottoms of the pots are dry, but evaporating water from the container can create a more humid microclimate around your Hoyas!

   
   

4. Light

   At a minimum, Hoyas prefer bright, indirect light or, as Steve likes to say, "bright shade" (which seems like an oxymoron, but is exactly what most tropical plants need!) If light levels are too low, your Hoya may begin to look pale, and it may resist flowering. Full sun, however, will often cause burns on the foliage and leave your plants looking "fried." The sweet-spot is a bright spot near a window (or under full-spectrum LED lights), where the plant is out of direct sun, at least most of the day. We say "most of the day" because many collectors do like to sun-stress their Hoyas, which may yield some amazing red and purple tones on the leaves of many species. Our best advice is to place your plants completely out of direct sun when you first bring them home, in order to let them acclimate. Then, if you want, try gradually exposing them to increasing amounts of sun, up to a few hours a day, while carefully monitoring for any burns or bleaching on the leaves. If this occurs, just back them away from the sun and let them recover, it's rarely fatal if you keep a close eye on the plants.

   
   

5. Feeding

   As with many other tropical plants, we like a two-pronged approach to feeding Hoyas. We use a pelletized, slow-release fertilizer in their potting medium with a 2-1-2 formulation to ensure steady feeding. We also apply a foliar fertilizer during their active growth months (everything but the short days of winter, depending on your latitude and exposure.) If you choose to try a different system, just make sure that it's an appropriate formulation for Hoyas and follow the manufacturer's instructions, erring on the side of under-, rather than over-fertilizing, if there's any doubt.
   

6. Temperature

   The final element of Hoya care is providing appropriate warmth. As you might guess from their tropical origins, Hoyas don't like to be chilled. Your plants will grow best and fastest in the range of 65 to 80 degrees Fahrenheit, which is conveniently within the range of most people's homes! When positioning your Hoya plant, consider whether it will be exposed to any drafts from air conditioning systems or doors in cold weather. Likewise, Hoyas enjoy some humidity, so avoid situating them directly in the path of heating vents or close to fireplaces or wood stoves.

The Joy of Propagation: Making More Hoyas at Home

Many Hoyas can be easily propagated at home, provided you have some patience. Having plants to share with friends (or just to enlarge your own indoor jungle) is one of the joys of plant-parenthood, and Hoyas are generall pretty easy to reproduce, with a few basic elements:

• Experiment with Your Propagation Medium

Depending on the species, we use various media for growing Hoya cuttings. For species with adventitious roots (the little, hair-like roots that form along the main vine, far from the soil surface), we generally use our Specialty Tropials Hoya Medium, topped with a layer of high quality long-fiber sphagnum moss. The moss holds plenty of moisture and allows the roots to take hold quickly. For others, like Hoya carnosa compacta (the Hindu Rope Hoya), we use ST Hoya Medium topped with a layer of perlite, which is a volcanic mineral that's "popped" like popcorn under heat and pressure. Perlite has a rough surface which allows roots to take hold, and it also ensures good air circulation, preventing rot while the cuttings are growing. Other species do well in plain water (change the water every week, at least), vermiculite, or other media.

• Humidity is Key

For success with Hoya cuttings, you'll need humidity on the higher end, usually 60%+, so we recommend a terrarium of some sort--but that doesn't require any special equipment. You can simply place the pots with cuttings inside a large plastic bag. Make sure that the pots don't continually sit in water, and gather the top of the bag, but don't tie or seal it, so too much moisture doesn't condense inside. Maintain this humidity at least until the cuttings are well-rooted, which may take from weeks to months, depending on the species.

• Cuttings Like Warmth

While they're rooting, make sure your cuttings stay warm and don't experience any draft or chill on a recurring basis. A heating mat, used for sprouting seeds for the outdoor garden, can be helpful if your home is on the cooler side.

• Don't Rush!

When rooting plants from cuttings, it's always tempting to repot as soon as new growth is visible, but Hoyas have fairly delicate, fibrous roots, and will thrive better if you allow them to grow a good bit, even becoming somewhat rootbound, before transplating them out of their original containers.

What Could Possibly Go Wrong?

Hoyas are generally pretty easy to grow with the basic conditions outlined above, but there are a few common bugaboos to watch out for: Pests:

Mealybugs are by far the most common pest on Hoyas in the home environment. These small scale insects are covered in a wooly coat and look like bits of cotton. They usually appear in the leaf axils (where the leaf meets the main stem), undersides of leaves, and near the soil line at the base of the plant. Mealybugs are most often brought into the home with newly-purchased plants, and they can spread like the measles if not stopped, infesting all your susceptible plants in short order. Besides piercing stems and drinking sap, Mealybugs leave behind fecal deposits that look like soot on leaves and stems. If enough of them infest your plant, you'll often see mishapen new leaves as a result of their impact. To prevent this, be sure to inspect your plants up-close every week or so. As an easy way to remember, we always do this when watering. If you see evidence of Mealybugs, immediately separate any infested plants from the rest of your collection, then evaluate how many you're dealing with. A few insects can easily be removed by hand, using a cotton swab dipped in 70% isopropanol (rubbing alcohol from the drugstore.). Just place some alcohol in a separate container, then dip a swab until it's saturated with alcohol, and press it against each Mealybug you see. The alcohol instantly dehydrates and kills the insect, and will also kill any eggs or larvae it touches. When you dab them with alcohol, you'll see that the wooly coat melts away, revealing a tiny insect that looks almost like a small brown seed. Use the swab to wipe these away, and be sure to use a clean cotton swab for each plant, at least. In case of a really bad infection, you may be faced with having to discard one plant to save the rest. In this case, our "last-ditch advice" is to purchase a spray can of 70% alcohol or place some in a clean spray bottle and spray your plant until it is saturated and dripping. Because the larvae hide in the soil and around the edge and seams of the pot, we recommend a spray on the soil surface, and wiping down the pot with an alcohol-soaked paper towel. After treatment, continue to quarantine affected plants for at least a week, until there is no sign of recurrence. Aphids

Like Mealybug, Aphids are sucking insects whose mouthparts are designed to tap into plant stems and drain their sap. Aphids tend to appear on the newest, most succulent growth, and they appear as tiny, often translucent, insects, clustered on the stems near the tips of the plant. They can be removed with the cotton-swab method in the case of a few, or by spraying the plant with neem oil (follow manufacturer's instructions for mixing, and add a drop or two of basic dish detergent to increase saturation) or insecticidal soap. Follow quarantine procedure to ensure they don't recur, before adding affected plants back to your main collection. Spider Mites It's often said that Spider Mites, with their thin wispy webs on the undersides of leaves, are tied to low humidity levels, but recent studies have demonstrated that isn't so. What we do know is that they'll cause leaves to appear listless and dry, often with speckled or grayish undersides. They also result in distorted new growth. To treat for them, use neem oil or insecticidal soap, or in case of recurring infestations, try a granular systemic pesticide designed for application to the soil surface. As always with pests, separate any affected specimens from the main collection until they're clear of Spider Mites.

Mealybugs Aphids Spider Mites

Disease:

By and large, Hoyas are pretty resistent to disease, which is just one more thing that endears them to us! Of the things that can happen, root rot is probably most common, and almost always is the result of the potting medium staying wet between waterings. To prevent it, be sure you're using a medium that allows for good drainage and air circulation, empty any water from under the pots, and allow the plants to dry somewhat between waterings. In the home environment, once every week to ten days is often a good schedule for watering them.

Another issue that may appear in the more succulent Hoya species is edema, which is swelling that leaves the foliage feeling "pulpy" or "flabby", and is the result of inconsistent watering habits. To correct it, be sure you're following a consistent cycle of thorough waterings separated by a long enough spell to let the pots dry at least an inch below the soil surface. A few viral, bacterial, and fungal diseases can affect Hoyas, but these are pretty rare in the home collection.

Being a Good Plant-Parent: Educate Yourself

For more information about individual species, we recommend you explore the websites for some societies dedicated to Hoya lovers. The American Hoya Society and The American Hoya Society are both excellent resources.

I'm All Set...Now Show Me the Hoyas!!

For a wide assortment of healthy, easy-to-grow Hoyas, from the common to some of the rarest in the world, visit us online: www.specialtytropicals.com