Caren White is a Master Gardener and instructor at Home Gardeners School. She has been associated with Rutgers Gardens for over a decade.
The first time that I saw a hoya, I thought that it was fake. The leaves were too shiny and the flowers too fuzzy to possibly be real. I realized my error when I saw nectar dripping from the flowers.
What are Hoyas?
Hoyas are a species of flowering vines that are native to Southeast Asia and Australia. They get their nickname, wax plant, from their leaves which have a waxy appearance.
The species most commonly grown as a houseplant is Hoya carnosa. It has been in our homes for 200 years and earned the Royal Horticultural Society’s Award of Garden Merit. This hoya species is known for its sweetly scented pale pink flowers with red centers. The flowers produce a nectar which insects find irresistible when the plants are placed outdoors.
Hoya carnosa vines grow between 2 and 4 feet long. They can climb, but are most often grown in hanging baskets so that they can drape gracefully over the sides.
The flowers are star shaped. They grow in clusters known as umbels. The blossoms are covered in tiny hairs. They emit scent in the evening to attract pollinators that are active at night.
How to Grow Hoyas
Hoyas are only hardy in zones 10 – 12. Most of us grow them as houseplants. They prefer full sun, but will tolerate a little shade. Plants that don’t get enough sunlight won’t flower so if your hoya is not flowering, move it to a sunnier spot.
Well-drained soil is a must because the vines are prone to root rot. Try adding some potting soil formulated for orchids into your potting mix. You can also use perlite in your potting soil to help with drainage. Allow the pots to dry out between waterings so that the roots are not constantly sitting in wet soil.
Fertilize your plant monthly during the growing season using a balanced fertilizer or a fertilizer formulated to promote flowering. There is no need to fertilize during the winter when the vines stop growing.
In colder growing zones, you can bring your hoya outside during the summer. Move your vines outdoors in the spring when night time temperatures are consistently above 60⁰F. Bring them back into the house in the fall when night time temperatures fall below 60⁰F.
How to Prune Hoyas
Hoyas can become unwieldy and benefit from a little pruning. They can be pruned any time, but right after they finish flowering is best. The plants bloom on “old wood”, meaning the flowers develop on last year’s growth. Any growth produced during the current year as a result of pruning will not have any flowers until the following year. So if you prune before the plants bloom, you will be cutting off parts of the vines where flowers would have formed resulting in few or no blooms that year.
You should never prune any of the spurs. The spurs, also called peduncles, are where the flowers form. They get longer every year, eventually reaching a length of 12 inches. If you remove a spur, no more flowers will be produced until it grows back. New spurs will not flower for the first year or two.
How to Grow Hoyas From Stem Cuttings
Make your cuttings when the plant is actively growing in the spring or the summer. Take a 4 inch cutting from the tip of a stem. Remove the leaves from the bottom 2/3 of your cutting. Make sure there are at least 3 leaves remaining. Dip the cut end in rooting hormone to speed up the process of growing roots. Then gently push the cutting at least 1 inch deep into a container filled with moist, well-drained soil. Cover the cutting and the container with a plastic bag to create a humid environment. Place the container on a sunny window. Check the soil every 3 days to make sure that it is not drying out. Roots should begin growing within 3 to 4 weeks. You will know that roots have developed when the plant starts to produce new leaves. Plants without roots cannot grow new foliage.
How to Grow Hoyas by Air Layering
Air layering is a type of propagation that allows you to root a “cutting” that is still attached to the plant. This is best done in the spring on a stem that grew last year or in mid- summer on a stem that started growing in the spring.
The first step is to “wound” the stem. This is where the new roots will develop. Using a sharp knife, gently scrape away the top layer of the stem. Your cut should be 1 to 1 ½ inches long. Then wrap moistened sphagnum moss around the entire stem where you made the cut. The moss will act as the “soil” for the roots to develop in. Wrap plastic wrap around the moss to hold in the moisture, fastening it securely with string, rubber band or tape.
You should start to see new roots develop in 3 to 4 weeks. When you see roots all the way around, you can sever your cutting from the main plant. Plant your new vine in a container or hanging basket filled with well-draining potting mix.
© 2019 Caren White