Hoya

FAMILY: Asclepiadaceae (The Milkweed Family)

GENUS:Hoya

SPECIES:There are 150 to 175 actual species plus many varieties.  

DISTRIBUTION: Hoyas are found in tropical Asia such as in areas of the Philippines that include 7,000 tropical islands, East Indies, Japan, Borneo, Sumatra, Java, Malaya, India, Bali, Sri Lanka, Bangladesh, Burma, Himalayas, Thailand, Indo China, Indonesia and Siam. The largest concentration of hoyas are in New Guinea, the 2nd largest island in the world… 400 miles wide by 1500 miles long with mountains up to 16,400 feet.

HABITAT: Many hoyas are from lowland tropical rainforests where they wrap around and/or hang from pockets in the high jungle trees and are semi-epiphytic (not parasitic). They like constant moisture (200 inches of rain per year for some) and high humidity. Some hoyas are more succulent than others as they go up so high in the tress that they lose contact with the ground. Some prefer limestone ledges of higher altitudes and misty mountain tops. In the tropics, they don’t have seasons – only periods of wet and dry times. Those hoyas that come from places like inner Australia have periods of drought and the monsoons may be every 3 to 5 years so they have developed thick succulent leaves.

DESCRIPTION: Hoyas are mostly enjoyed for their interesting leaves and because they make nice hanging baskets. The leaves are all shades of green, green with silver flecking, green edges with colorful centers, green center with pink and white variegation on the edges, and the veins in some make dark patterns on the leaves. The leaves can be shiny, dull, fuzzy, leathery, velvety, rough or smooth… or one side can be fuzzy and the other side smooth. Leaf size varies from ½" long to ½" wide by 8" long (H. Longifolia), to 6" wide by 6 ¾" long (H. diversifolia), to perfect heart-shaped leaves (H. kerrii), or leaves that twist and curl (H. compacta), to 10""leaves (H. polystachya). FLOWERS/BLOOMS: Hoya blooms are the prize we receive for good cultivation. They are star-shaped and many are fragrant. Usually they have 20 to 30 flowers per umbel, some will have many more (up to 60), others can have as few as 2 to 4 blooms per umbel. The size will vary from ½" to 3" in diameter.

SOIL: should be ½ sterile soil and ½ perlite or vermiculite to make a fast draining potting mix. Use small pots because the root system is small (in nature they grow in crevices where only a small amount of debris gathers). When you repot, do it when the plant is growing and increase the pot size to just a little larger than its last pot. Roots need to fill most of the pot as hoyas bloom more freely when roots are restricted.

LIGHT: needs to be bright to insure blooms. Hoyas prefer early morning sun from 7:00 A.M. to 10:00 A.M. They grow well when hung under trees for filtered light and protection from storms.  

WATER: when soil is dry about ½ the pot depth… never let the soil dry out completed. Reduce watering somewhat during the winter.

FERTILIZE: when signs of growth resume in spring. Use ¼ strength Superthrive, Superbloom or BR61 with each watering… or you can use Osmocote with low nitrogen. Always feed when roots are wet.  

PRUNE: hoyas for new growth and blooms. Long stringy growth can be cut back. Peduncles (bloom spurs) should not be pruned unless desired. A few hoya species shed these bloom spurs after blooming and form new ones each year. Do not spray hoyas with anything but water if temperatures are over 80° F (26° C).

PESTS: you must guard against are mealie bugs and aphids. Always keep a spray bottle filled with ½ alcohol and ½ water for quick kill of visible pests. Checking your plants for these bugs should be done often. For root mealies, dip entire plant and pot into a container with a solution of ½ tablespoon of Malathion to a gallon of water. If your soil is too full of mealies, take cuttings and get rid of the pot, the old soil and the roots (burn these items, never dump them into your compost pile). A fungus may develop (spots on leaves) if the plants are kept wet for too long. Spray with fungicide and repot.

Here is a list to help with some problems that may occur.

Yellow Leaves
· roots too cold
· soil too wet (or excessively dry)
· too much sun
· nitrogen deficiency
· anemia—soil mix too acid or too alkaline Plant Dropping Flower Buds
· excessive heat
· lack of humidity
· soil too dry
· hot or cold draft No Blooms
· not enough light
· improper feeding
· extremely low humidity
· pot size too largeA FEW HOYA SPECIES BY TYPE AND SIZE
Large Growing Hoyas
· H. diversifolia B
· H. obovata
· H. macrophylla
· H. latifolia
· H. polystachya
· H. kerri
· H. fraterna
· H. imperialias
· H. archboldiana
· H. macgillivrayii (formerly called H. megalaster) Bushy Hoyas
· H. multiflora
· H. cumingiana
· H. densifolia Pendant Forma
· H. bella
· H. polyneura Mini Creeper
· H. serpens Small Growing Hoyas
· H. gracilis
· H. serpens
· H. Angustifolia
· H. curtisii
· H. lacunosa
· H. camphorifolia
· H. obscura Easy To Grow
· H. fungii
· H. pubicalyx
· H. australis
· H. carnosa FLOWER COLORS range from white to ivory, yellow to tan and from pink to red, purple and cordovan brown. There are also some species with lime and mint green flowers. The flowers can also be fuzzy or waxy. The color of the blooms is not a good taxonomic characteristic because the colors often vary and the weather and growing conditions can also effect bloom colors. It is the structure of the reproductive parts of the flower that is important in distinguishing one species form another. PROPAGATION: The easiest way to propagate hoyas is from fresh cuttings taken from spring to mid-summer. Cut off a length of vine or branch at least 2 to 3 joints (nodes) long, just below the leaf node. Remove the leaves at the base of the cutting, dip in root hormone, and insert it into a moist rooting medium containing perlite, vermiculite or a half and half mixture of these two products. Use a 3" or 4" pot. Place the pot into a Zip-Lock baggie sealed all but an inch. Do not disturb until you see some growth (2o to 3 weeks). OR, hoyas can be rooted in warm water and when the cuttings grow ½" roots, plant in the above mix. A single leaf does not make a new plant…you must have leaf nodes. Growing from seed is possible but the seed must be fresh and the seed growing mix must never be allowed to dry out or you will lose your seedlings. Tiny seedlings are also very susceptible to the fungus disease called "damp-off" which can wipe out an entire seed tray of seedlings in a few hours. Spray your seed tray with fungicide before you plant your seeds and every 5 to 7 days thereafter until your seedlings are mature enough to survive on their own. CULTIVATION: Since these plants are tropical, they do not require a winter rest. 50° F (10° C) is a winter minimum for them. They grow best and are at their happiest with temperatures between 60 and 80° F (15 to 25° C). A humidity level of 50%-plus is their preference.