How to grow hoya

What are hoyas?

Hoyas, or wax flowers, are native Indo-China, Indonesia and Australasia. They are tender, so must be grown indoors in the UK, either all year round or throughout the cooler months. They like plenty of light, warmth and some humidity, either in a bright room or warm conservatory. 
 
The small, white, star-shaped flowers are shiny and waxy, held in domed clusters, and are highly fragrant, especially at night. For successful flowering, hoyas need plenty of light and careful watering, as they may drop their buds if the compost is too dry or too wet or if light levels change, so don’t move them while in bud. After flowering, you may get a second flush if you leave the flower stalks in place.
 
In the wild, hoyas often grow as epiphytes, on tree branches or in bark crevices, rather than in the ground. As they have less access to moisture, they have developed semi-succulent, leathery leaves that can store water. They are climbers or trailers, so as houseplants they are usually grown up a support, such as a wire loop or tripod of canes, or allowed to trail from a hanging planter or high shelf. Some species can grow quite large, but can be pruned annually to keep them smaller if necessary.  

Choosing hoyas

There are many hoyas to choose from, including:

• Hoya carnosa AGM – a vigorous climber or trailer, with fleshy leaves and clusters of fragrant white or pink flowers with a red centre. If left unpruned, it can get quite large, so could be grown up a trellis in large conservatory. There are several cultivars, including ‘Tricolor’ AGM with trailing stems of white-splashed leaves 

• Hoya lanceolata ssp. bella AGM – more compact, with downy trailing stems and fleshy leaves, ideal for a hanging planter or trained around a wire loop. Pendent clusters of scented, white flowers with lilac-pink centres

• ​Hoya linearis AGM – a trailing species with slender stems covered in narrow fleshy leaves and white fragrant flowers. It’s ideal in a hanging planter

Buying hoyas

Hoyas are available from houseplant retailers and tropical plants specialists. 

For tips on choosing good quality plants, see our guides: 

Hoyas can be kept in their original container for several years, until the roots fill the pot. Spring is the best time to repot them.
 
Choose a pot that’s only a few centimetres larger than the rootball, to avoid overpotting. If the new pot is much bigger, the compost will stay wet for longer, which can cause the roots to rot.
 
Use a sharply draining, well-aerated compost, such as an equal parts (by volume) mix of orchid bark, peat-free multi-purpose compost and coarse perlite. Alternatively, use cactus compost with added perlite.
 
See our guides to repotting:

Location

Hoyas like a bright position, but out of hot sun in summer, as this can scorch the leaves. Position them away from radiators or heaters, and out of cold draughts.
 
Hoyas can be moved outdoors in summer to a warm, sheltered spot, to add exotic flowers and fragrance to a doorstep or patio. But never move plants once flower buds have formed, as they may drop the buds if light levels change.

Temperature

Hoyas are tender and enjoy average room temperatures in spring and summer, at 16–24°C (61–75°F). If moved outside in summer, take care to harden them off first, and bring them back indoors before night temperatures fall below 16°C (50°F). 
 
They should be kept cooler and drier over winter, as they go into a semi-dormant state. Provide a minimum night temperature of 10°C (50°F) for Hoya carnosa AGM and 16°C (65°F) for H. lanceolata ssp. bella AGM. 

Watering

Water hoyas regularly throughout the growing season, from spring to autumn. Keep the compost moist but not waterlogged – always let the water drain away, otherwise the roots may rot.
 
From October to February, hoyas are relatively dormant and need only moderate watering. Wait until the compost is fairly dry, but never let it completely dry out. Damp conditions in winter can rot the roots and kill the plant.

Humidity

Hoyas dislike dry conditions during the growing season, so raise the humidity, particularly in warm weather, by
standing the container in a saucer of damp gravel or clay pellets. Keep the water level just below the surface of the gravel, so it doesn’t saturate the compost. 

Feeding 

Hoyas only need light feeding. In spring and summer, apply every couple of weeks – a balanced orchid feed (preferably free from urea) is ideal. Flush out the pots with plain water every few months to prevent a build-up of salts. Hoyas shouldn’t be fed for five to six weeks after repotting.

In autumn and winter, reduce feeding to once a month until growth resumes in spring.

Deadheading

Resist the temptation to deadhead hoyas – if the flower stalks are left in place, more blooms will often sprout from the stumps of previous clusters.

Pruning hoyas

Light pruning in late winter/early spring will help to keep these vigorous plants to a manageable size. Always wear gloves when pruning hoyas, as the milky sap is toxic and can irritate skin. 

Simply prune out any overcrowded or weak shoots at the end of February. Make your cuts just above a side-shoot or leaf.

Hoyas don’t respond well to hard pruning, so plants that have outgrown their space are best replaced.

Training hoyas

Hoyas are climbers or trailers – so provide support such as a wire loop or tripod of canes if you want them to climb, or position in a hanging container or on a high shelf or mantelpiece if you want them to trail. 

Hoya carnosa AGM is a particularly vigorous climber and if you have space in a large conservatory, you could train it along horizontal wires attached to a wall. 

You can make new hoyas for free by layering and taking cuttings in spring or early summer. Wear gloves, as the milky sap is a skin irritant.

Layering

• Fill a container with peat-free cuttings compost

• Choose a strong, low-growing shoot. Bend it down into the new container, and peg it into the compost. Remove any leaves that are in contact with the compost

• Keep the compost moist until the shoot has rooted

• Once well-rooted, sever it from the parent plant

Semi-ripe cuttings 

• Take cuttings from the previous year’s stems in spring or early summer

• Stand the cuttings in a glass of water and they should form roots in two or three weeks

• Once they have plenty of roots, pot them up into peat-free cuttings compost and keep well watered

Hoyas are tender plants and require suitably warm, bright, humid conditions, along with regular, careful watering and feeding in spring and summer, to grow and flower successfully. They can be tricky to keep happy, so look out for the following issues:

• Dropping leaves, blackening leaves and dieback – probably due to poorly drained or waterlogged compost, or being too cool in winter

• Wilting and die-back of stems – often caused by overwatering or overfeeding. Too much fertiliser can lead to high levels of salts in the compost, which can prevent roots absorbing water

• Root rot – from overly wet or poorly drained compost. Plants won’t usually recover, so take cuttings as soon as you notice this problem

• Failure to flower – may be due to insufficient light

Also check plants regularly for sap-sucking insects, including: 

• mealybugs

• glasshouse whitefly

• scale insects

See the following guides for more tips:

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