Gardening can not only keep you physically fit but it can also benefit your mental health. Sadly many people don’t have the time or space to take on an entire garden. If this is the case then why not start with a houseplant or two? Caring for these little plants is just as beneficial and adds a bit of colour to your home.
The Hoya is a popular houseplant. Originating in Asia and Australia it is named for Thomas Hoy, the man credited with giving the plant its popularity. Hoy was the Duke of Northumberland’s gardener in the late 18th and early 19th century.
Commonly known as the ‘wax plant’ because it looks as if it has been carved from wax these plants are striking when displayed from indoor hanging baskets or when their long stems have been trained along a trellis.
The distinctive flower of the Hoya Bella has a sweet aroma.
Adding to the colourful display are small clusters of sweet smelling flowers. In more milder climates the Hoya can be grown outdoors where they can compliment your stylish patio furniture.
An evergreen climber it suffers from relatively few pests and diseases. Additionally it is a relatively care free plant meaning that it is one of the easiest flowering houseplants to grow. This makes it an ideal starting point for beginners or nervous gardeners.
Different Types of Hoya
The exact number of Hoya species is not known, estimates place the number at between 100 and 550. While we don’t have the time to look at every species here is a brief guide to some of the most popular and commonly grown types.
Also known as the ‘Wax Plant’ or ‘Porcelain Flower’.
With its distinctive almond shaped dark green leaves the Hoya Carnosa is the most common variety. A sweet smelling plant it is usually grown as a vining plant it is said to be a great cleanser of indoor air pollutants.
The sweet, white flowers of the Carnosa, sometimes known as Milkweed.
There are a number of different variations of the Hoya Carnosa including the variegata ‘Tricolor’. This adds white and pink lines to the classic Hoya plant as well as stems of bright pink. Another variation, ‘Rubra’, sometimes called the ‘Crimson Prince’, also has a distinctive appearance. It’s variegated foliage includes cream, yellow, and pink hues.
Also known as the ‘Common Wax Flower’ or ‘Wax Vine’.
Butterflies love the shiny succulent leaves and pretty pink flowers of this variety. A lover of sunlight is flourishes on the edge of rainforests and rocky outcrops in Australia. This variety is marked with distinctive silver splashes on its leaves.
Also known as ‘Lucky Heart’ or the ‘Sweetheart Plant’
Known as ‘Sweetheart’ because of its heart shaped leaves it is a popular houseplant in south east Asia and a common gift on Valentine’s Day.
The ‘Sweetheart’ is a common gift amongst lovers.
If you purchase this variety you may find that it is a single heart shaped leaf in a pot. It may take a few years before the plant really begins to develop in size but your patience will be rewarded with plentiful vines and plentiful pink and yellow flowers.
A pretty dwarf variety. This small growing species produces slender upright branches that droop down as the plant ages. Unlike other varieties this is not a climber.
‘Bella’ has small leaves that are thick to the touch and dark green in colour. Complimenting this are the flowers, white in colour with flashes of purple at the centres.
|Common Name||Waxplant, Waxflower, Waxvine|
|Grouping||Houseplant/ evergreen climber|
|Origin||Asia, Australia, tropical climates|
|Flowering Period||Late spring to autumn|
|Watering Requirements||Sparing, when soil is dry|
|Light||Bright, indirect light|
|Temperature||At least 50°F, some like it warmer. Likes humidity.|
|Height/ Spread||18 inches by 12 ft.|
|Propagation||Stem cutting, leaf cutting, layering|
Caring For A Hoya
As we have already noted the Hoya is a low maintenance plant, this means that it dislikes being overly handled or pampered. This does not mean that you can completely neglect it. With the right care and attention your will be rewarded with a healthy plant which sprouts distinctive foliage and sweet smelling blooms during the spring and summer months.
Here is an easy to follow guide to help you care for your Hoya.
Positioning Your Plant
Hoyas like to be in a bright spot. Try to find a place where the plant will get lots of indirect light. An east or west facing window is ideal.
If you wish to place the plant in a south facing window then hang a sheer curtain or net curtain in the window to prevent the plant being exposed to too much direct light. While Hoyas like light too much direct, bright light will damage the foliage and harm the plant.
Hoyas like lots of bright, indirect light
If your plant doesn’t flower or stops flowering it is probably a sign that it isn’t getting enough light. Try placing it in direct light for a few hours every day. If you are unable to provide a natural source of light a grow lamp will provide a good alternative. You don’t have to purchase anything too fancy, a regular standard lamp will do the job just fine.
Once you have found your ideal place try not to move the plant. Many growers believe that you should never move, or even touch, your Hoya when it is in flower.
Hoyas don’t require too much watering. If you are watering your plant too often then leaf drop may strike. If this happens simply reduce the frequency with which you water your plant.
If you are unsure how often to water your plant it is usually best to wait until the soil is almost completely dry before watering. Remember that your plant will need to be watered more in the growing months, spring and summer, than at other times of the year.
Knowing how much water to give your plant can also be difficult. The most reliable method is to hold the plant in it’s pot over an empty basin or sink and water it until the water begins to drip from the bottom. This is a sign that the soil has taken on as much water as it can.
If the soil becomes too waterlogged or you allow the plant to sit in water for a prolonged period the plant’s roots may become too wet. If this happens the roots will be unable to absorb oxygen, vital for keeping the plant healthy, and may develop root rot.
While it is not always possible try to water your plant in the morning. This allow the plant to soak up moisture through the day and for the leaves to dry before temperatures fall. Wet leaves in cold temperatures is a breeding ground for rot and disease.
Many people like to use tap water that has been allowed to reach room temperature. This is because cold water can stress the plant and cause it to lose its leaves.
Also it is recommended, if you have time, to let the tap water sit in an open container for a couple of hours before watering. This gives the chemicals present in the water, that are potentially harmful to plants, time to dissipate. If you are worried about the water in your taps a water purifier is easy to use and will give you peace of mind.
Generally you will need to feed your Hoya every three to four weeks in the spring and summer. It won’t require feeding during the dormant winter months.
If you notice that the leaves and stem of your plant become pale increase feeding to once every two weeks. If new growth seems darker than usual and with short stems appearing between the leaves then reduce feeding to every six weeks.
Regular feeding of your plant will reward you with lots of pretty flowers.
The easiest way to feed your houseplant is with a general purpose, water soluble houseplant fertiliser. Remember to water the plant before applying the fertilizer. Adding fertiliser to dry soil can burn the plants roots. The dilution rate is commonly 1 teaspoon per gallon of water but this can vary so check the label before feeding.
If you are worried about how much or often to feed your plant remember that too little fertilizer is far safer than too much.
Finally, once your plant is established about a month before it is due to flower switch to a high phosphorus fertilizer. This will encourage it to produce stunning floral displays.
Temperature and Humidity
A tropical plant, in the growing season (spring and summer) Hoyas like a medium to warm location, about 50°F. Some varieties prefer it to be even warmer so always check the plant care information on the label. If you are growing your plant indoors temperature is not a problem as most homes are between 60 and 70°F.
If your Hoya is an outdoor plant remember to bring it inside or into a greenhouse when temperatures begin to fall.
Hoyas also like it humid. Some people like to mist their plants frequently. Not only does this help to keep the leaves clean but it also increases the humidity levels around the plant. If you choose to do this be careful not to mist when the plant is budding or in flower. This can damage the flowers.
It can be particularly difficult to maintain humidity levels in the winter months because central heating can make our homes very dry. An indoor humidity monitor or air quality monitor will help you to monitor humidity levels around your plant.
Terrariums can help to maintain temperature and humidity levels as well as adding interest to smaller plants that are yet to flower.
If you want to make sure the humidity levels around your plant remain high then stand the plant pot on a tray of gravel or lightweight aggregate and fill it with water. Keep the water level slightly below the surface of the gravel so that the plant pot isn’t standing in the water. Not only will this maintain humidity levels but it can form part of an attractive display.
Repotting Your Hoya
Unlike other plants the Hoya likes to be a bit rootbound. This encourages the production of flowers. Despite this the plants will, eventually, outgrow their containers. The most obvious sign that it is time to repot your plant is when roots begin to poke out of the drainage holes at the bottom of the pot.
The best time to repot is in early spring before the growing season has begun in earnest. Many growers also avoid feeding the plant for 5 or 6 weeks after repotting. This helps to give the plant some time to get established in its new pot.
When you come to repot your plant don’t go for a massively large pot. Too much space will stunt growth. As long as it is clean something slightly bigger than the initial pot, or even the same size, will be fine.
Remove the plant from it’s old pot. Gently shake off any dirt that is clinging to the roots.
Take care when repotting not to damage your plant
Next put some fresh potting mix or all purpose compost into the new pot. When positioned your plant should not be any lower than it was in the original pot. Hoya plants like some airflow around the plant. This helps to avoid rot and decay.
If you are unsure what type of soil or compost to use remember that Hoyas dislike heavy soil. A moist, well-drained light soil with some added perlite is ideal.
Some growers like to make their own mix. If want to mix your own try a mix of one part pine bark to two parts peat moss. Adding a bit of dolomitic lime can help to reduce the acidity in the mix. Perlite will then lighten the soil and help to improve drainage.
However this isn’t necessary. You can purchase good quality potting soil from any garden centre. If you think this soil is too heavy add perlite to lighten it. If you want to read more about the different types of soil and compost available this is a good guide.
When you are happy with the position of the plant add more compost or potting mix. While you want to fill the pot try not to pack in so much that it becomes compacted. Also try to leave some space between the compost and the top of the pot to allow for watering and growth. After you have planted your plant water in well and return the it to its usual spot.
To learn more about repotting house plants this is a useful guide.
Some varieties of Hoya such as Carnosa are strong climbers and need to be trained around a trellis or similar support. Others such as Bella prefer to be grown in a hanging basket so that their stems can drape down.
Whatever variety you choose to grow some pruning and training will be required.
The best time to tidy up your plant is at the end of February, just before the growing season begins.
Don’t be tempted to use your blunt kitchen scissors, this can do more harm than good. Instead use either a bonsai pruning shears or a regular pruning shears. Either will allow you to make neat, precision cuts.
To prune carefully remove any wilted, damaged or dead leaves and branches. These are easy to identify as the will be yellow or brown in colour. Also prune anything that looks chalky or dusty. This could be an early sign of disease and removing it will stop the spread.
After this any pruning you choose to do is only for appearance. While the Hoya is a hardy plant pruning should be done with caution. Remember that new flower growth can occur on older flower stems, sometimes called spurs. These will flower year after year so be careful not to remove any flowering spurs.
Also try to resist the temptation to remove too much of your plant’s trailing length. These arms are not only an attractive feature but are also vital to helping the plant grow.
Cuttings and Propagation
Propagation is easily done from stem cuttings. The best time to do this is in the spring or early summer. While I will now explain how to take successful cuttings the RHS has a good in depth guide to propagation here
Take a cutting from the previous years growth. Stem cuttings can also be taken from the plant’s new growth. The cutting should have a few leaves and be a couple of inches long.
Place the cutting in a small pot with moist fresh potting soil. Some people like to dip the cut ends into a rooting hormone before planting but this is not necessary.
Put the pot in a warm and bright area. Water regularly so that the soil doesn’t dry out and make sure the humidity levels are good. You should see new shoots in a month to six weeks.
A propagation chamber lowers the risk of shock after planting cuttings and is worth a try if you’ve had a hard time with your cuttings. If you don’t want to invest in one a homemade version is just as good and can be made from a plastic food container like these.
You can also root the cuttings by placing them in a vase of water. A clear vase will enable you to see roots sprouting within a few days. However be careful as when you transplant the cutting to soil the plant may go into shock.
Placing the cutting in water will encourage roots to sprout.
Either of these methods will, if successful, produce a flowering plant within two years.
Leaf cuttings can be taken by snipping the leaf off just below the petiole and planting it in a pot or vase of water to root. This is the slowest way to propagate Hoya it can take a couple of years before any significant growth appears.
Finally air layering is the easiest, and quickest, way to propagate a Hoya. Simply pin a tendril down at the joint into some fresh, moist compost or rooting medium. When roots form in the new pot sever the stem. You are now able to repot your new plant.
The Hoya rarely produces viable seed because of this they are rarely grown from seed.
Pests, Diseases And Other Problems
Unlike other plants the Hoya is not prone to pests or disease. However there are a few things you need to watch out for.
While pests will attack the Hoya it is not their first choice of plant so infestations are uncommon.
The most common problem will be aphid infestations. However these can easily be contained with a insecticide spray. Fungus gnat and mealy bugs can also be a problem but, like aphids, are easily dealt with by the application of an insecticide.
If you wish to stay away from chemical deterrents applying either warm soapy water or neem oil to the leaves will have a similar effect.
Ants and red spider mites are sometimes attracted to the Hoya. Both can both be deterred by the occasional application of malathion spray.
The worst possible pest is the root- knot nematode. Instead of trying to combat the pest it is easier to simply salvage as many leaf and stem cuttings as you can and begin again. Discard the soil and destroy the infected roots to prevent further spread.
The most common disease to afflict the Hoya is sooty mold. This is a black mold that appears on leaves that have been made sticky by plant sap or nectar. While this disease is sometimes caused by aphids often the flowers often produce so much sweet nectar that it causes this disease itself.
Sooty mold may be unsightly but it is also easy to deal with. Simply wipe the leaf clean with a damp cloth.
Botrytis blight can also affect the plant. This will first appears as a grey coloured fungal patch on the centre of the plant. As it progresses leaves will become mushy or collapse. The application of copper fungicide, such as Bonide Copper Fungicide, will alleviate this problem.
The final disease to be aware of is root rot. This dreaded affliction is caused by excess moisture in the soil encouraging the growth of fungus. This is often the result of overwatering.
The most obvious signs of root rot are if your plant starts to wilt or brown or black lesions appear on the leaves or stem. If you notice any of these spray the soil and the plant with a copper fungicide.
Prompt application should reduce the effects of root rot. If the plant recovers in the future try to leave more time between watering. However if the roots also turn black or mushy then your plant is almost certainly beyond redemption and should be disposed of. If possible take cuttings of any healthy looking parts of the plant, this will allow you to start again.
Leaf drop, the blackening of leaves and the dieback of stems: these are often indicators of poor drainage or overly wet compost. In the winter months it can be a sign that the plant is too cold. If this is the case increasing the temperature or humidity levels will help. If the plant is small enough placing it inside a cloche or small greenhouse can keep it warm. If you don’t wish to invest in a mini greenhouse a homemade version using a ventilate food storage container will do the job just as well.
Treated correctly your will have scores of stunning blooms.
Wilting or die back of above ground growth: These are often signs of overwatering or too much fertilizer being applied. The latter can leave the soil too salty meaning that the roots are unable to absorb moisture. To solve either problem simply water or feed your plant less frequently.
Failure to flower: try placing the plant in a sunnier spot or under an artificial light for a few hours every day. If the plant is young you may need to wait until next year before it flowers. This will give the plant time to grow into its pot- Hoyas like to be slightly rootbound.
If your plant has flowered in previous years it may be that you have pruned the plant too heavily and removed the flower spurs from which the flowers grow. Applying a phosphorus fertilizer will stimulate growth.
With a little care and attention your plant will reward you will fragrant and attractive flowers and lots of interesting foliage.
And that is how you care for a Hoya plant. While this may sound like a lot to take on these plants are fairly robust so if you make a mistake it is not the end of the world. Remember if you are not sure it is better to under water or feed than overdo it.
With a little time, care and attention you will have a flourishing plant that will not only be an attractive addition to your home but also benefit your health and well being. It may even inspire you to start your own garden.