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International Hoya Association
Frequently Asked Questions  Web Page Title Graphic

   The question that arises more often than any other from new growers, is...Are there any books available? The second question from new and not so new growers is...How do I know which hoyas to buy?    The answer to the first question is...that until the past 10 years or so, there was very little literature available for the hoya grower. That all changed in the year 1992 when the "Hoya Handbook" written by the president of our organization, Dale Kloppenburg collaborated with Ann Wayman to publish the very first book on all of the known hoyas at that time. The book was an instant best seller in the hoya world and over the next few years two thousand of these books were sold. Since that time Dale has written many books about hoyas from the different localities where these plants grow.

   The answer to the second question on which hoyas to buy is found in every issue of Fraterna where many hobby growers and a few professional growers give detailed descriptions of which hoyas do well and perform the best under all kinds of different conditions. Almost all hoyas are easy to grow.

   The questions that I get the most often are these:

Q: Why don't my hoyas bloom?

A: That question crops up in almost every conversation that has ever been held concerning hoyas. You can hear every conceivable answer, most of them wrong. The truth is, that if a hoya is mature but hasn't bloomed, it is usually because it isn't getting enough light.

Q: How old do hoyas have to be before they bloom?

A: There are too many hoya species involved to give a pat answer to that question. Many hoyas will bloom in their first year of growth, some will take two years, others may need three or more years before they are mature enough to bloom. If conditions aren't right...mature or not, they may never bloom until those conditions are corrected.

Q: What can I do to correct my growing methods in order to get flowers?

A: For the majority of hoyas, the magic wand that brings on flowers is extremely bright but indirect light, no direct sun. If possible the humidity of your growing area should be kept above 40%, 60% would be even better but hard to maintain in a home. Keep a spray bottle handy and mist your plants often. Another hint that may help to bring on flowers along with your weekly use of a very weak solution of a balanced fertilizer is to give them a real jolt with a feeding of a high phosphorous fertilizer as a substitute for your regular balanced fertilizer occasionally.

Q: Which hoyas will bloom better in the shade?

A: Most hoyas will grow in the shade...most will never bloom under those conditions. The different varieties and sub-species of Hoya lacunosa seem to prefer filtered light for blooms but certainly not deep shade on a year round basis.

Q: Do hoyas bloom only in the summer?

A: Some hoyas bloom in the spring and summer, others can bloom off and on all year long. There are a few hoya species that bloom only in the fall and winter. These fall and winter bloomers are almost always grown in warm, humid greenhouses.

Q: Is there a "Magic" formula potting mix that is better than any other for hoyas?

A: Hoyas have a real advantage in that they adapt so readily to many different potting mediums that other plants would find unacceptable. Most of the pre-packaged, all purpose houseplant mixes work great right out of the sack but you may have to lighten some of them with Perlite (Sponge Rock). The main thing is to insure fast drainage so your plants don't remain wet and soggy. They must also be light enough so they don't become hard and compacted. Many hoya growers use a half and half mixture of sphagnum peat moss and Perlite with some added Dolomite lime, or a calcium source to neutralize the acid in the peat moss. Watch your plants! They will usually let you know if they are unhappy.

Q: Why is it that some cuttings will root, then sit and do nothing, while cuttings from the same plant, planted at the same time and under the same conditions will grow vigorously?

A: That is a mystery! Growth hormones within the cuttings, or lack of them is probably the cause. If you have cuttings growing well of the same plant, why not just dump those that don't grow. If it's an expensive cutting or one of a kind, and you have the patience to wait it out, they will eventually put out new growth.

Q: What is the best way to train a straggly looking hoya to a nice compact shape.

A: Wire or plastic hoops with built-in pot holders can be purchased, as well as wire, cedar, redwood and wicker trellises. These make beautiful displays when hoyas are allowed to twine around the hoops or wind in and out of the trellises. The major disadvantage to these devices is in trying to repot a plant that has spent several years entangling themselves in one of them. The best way to contain a climbing twining plant is to wrap the stems around the plant itself as it grows. Drastic pruning may be called for occasionally if the plant grows completely out of bounds.

Q: What color are hoya flowers?

A: Every color has been verified in hoya flowers except blue and black. H. Ciliata that is called the ˘black hoya÷ is an extremely dark purple. There are true oranges, greens, pink, red, many shades of yellows, some are even multi-colored, and of course many fantastic, pure sparkling whites. A few years ago, an amateur collector claimed to have found a ˘true blue÷ hoya...this hoya turned out to be ˘mauve÷ which is a light pinkish purple.

Q: Some of my hoyas have beautiful glossy foliage while others have a dull, dusty appearance, why is this?

A: Trying to diagnose what ails a plant without seeing the plant and the conditions under which it is grown is impossible. Any number of things can cause a plant to look dull, including natural aging of the leaves. Some hoya species just donĂt have glossy foliage to begin with, while others may have leaves and branches that are the texture of velvet or suede and by their very nature are not glossy. If the foliage on a plant that used to have a high gloss seems rather dull looking, check the new growth, unless it has an insect infestation or a disease of some sort, the new leaves should all have a high gloss. Make out a checklist and write down these questions: Have your plants ever had glossy foliage? Have they ever been allowed to dry out to a point of wilting? Have they been kept so wet that the roots have started rotting? Is your humidity extremely low? Are these plants sitting in a draft of cold or hot air, such as from a furnace or air conditioner? Have they been examined for an insect infestation? Answer all of these questions, and you can probably come up with an answer. It is sufficient to say briefly that anything that affects a plants root system will also affect the appearance of the foliage. Low humidity is a slow agonizing death for all tropical plants and normally shows up first in the appearance of the foliage. Low humidity also favors a spider mite attack which can cause foliage to appear dull and dusty looking.

Q: What kind of fertilizer or plant food do hoyas need for growth and bloom?

A: LetĂs re-phrase that question to read...What chemical elements can we provide that will help our hoyas (or any other plant) to make its own food. Without getting too technical, itĂs only necessary to say that all ˘green growing things÷ manufacture their own food from sunlight and water. All we can do as their human overseers is to insure that they have access to the essential chemical elements that their natural habitats normally provide for them. The most important supplemental elements are nitrogen, phosphorus and potassium. These three ingredients are vital components of a healthy plant. Without all of them in proper balance, a plant canĂt repair itself or build new cells for growth. Here I should also add that there are several trace elements in very small amounts that are important so when you are purchasing plant food, be sure that what you select states on the package or container that trace elements are included.

Q: What are the symptoms of a hoya that is deficient in nitrogen?

A: The lower or older leaves will usually turn yellow or pale, sickly looking green, dry and drop off; some may become brownish/orange. The new growth will rob the older leaves of any chlorophyll that is retained but there is not enough to support the new growth so it remains stunted, pale and often curled and distorted. The fastest remedy for a plant in this condition is a foliar feeding with a tablespoon of fish fertilizer mixed in a gallon of very warm but not hot water. Mist the entire plant very lightly with this solution. You want just a frost of mist on the leaves. Do this every week for several weeks, then go back to your balanced fertilizer. You will see a definite improvement in a very short time.

Q: What is meant by the expression Foliar Feeding?

A: Foliar feeding is a method of getting nutrients into a plant through the foliage instead of the roots. In nature, epiphytes get a large portion of their nutrients through their leaves when rain and mist washes debris, such as bird droppings, dead leaves etc. Down from higher up in the tree tops. We try to duplicate nature by using devices that apply needed nutrients as a very fine mist from a sprayer.

Q: Are there any hoyas that have a natural immunity to pests such as mealy bugs and aphids?

A: Nature has devised some clever ways for different plants to ward off attacks by insects and also from larger animals. This is usually accomplished through chemical means (the plant sap is poisonous or contains a chemical that stings). Some plants have developed millions of tiny thorns, others have developed huge, wicked looking and very dangerous barbs. Hoyas don't have any of these obvious weapons, unless itĂs chemical. There are some hoyas that never seem to be bothered with mealybugs. H. Micratha is one that I don't recall ever seeing with mealybugs or aphids. H. Obscura and H. Plicata are two that seldom have aphids but will occasionally have a few mealybugs. Wouldn't it be great if we could make up a brew of stewed, immune hoya leaves to spray on our other hoyas!

Q: What causes hoya buds to dry up and drop off without opening, or fall off within a few hours after opening?

A: Usually hoyas that dry up and drop their buds have been allowed to become too dry between waterings. Hoyas will also drop their buds if the potting mixture is constantly kept too wet. However they donĂt dry up in this case but become yellow and spongy, or brown and mushy. Your buds that open but fall off soon after are probably placed where a cool draft is hitting them, maybe from a fan.

Q: Can you tell me which hoyas grow wild in Hawaii?

A: There are no hoya species known to have evolved naturally in Hawaii. The hoyas that grow there now, have been lovingly planted by the ˘wild÷ but human hands of a couple of hoya collectors that live there.

Q: What is the best way to remove hard water spots from hoya leaves?

A: One teaspoon of vinegar (white or red) mixed in a pint of warm water will remove most water spots. Dip a soft cloth in this solution and rub each leaf gently in a circular motion, rinse with clear water and dry with another soft cloth. If you want a real shine to your leaves, try mixing one teaspoon of mayonnaise (not salad dressing) with three tablespoons of warm water. Apply to each leaf with a cottonball or soft cloth, then wipe dry. This formula does not clog the pores of your leaves like commercial leaf shine products and your leaves will absolutely glisten.

Q: Will hoyas grow and bloom under fluorescent light?

A: Absolutely! In fact many of the small growers are happier and do much better under artificial light than in natural light.

Q: If I grow hoyas in a light garden with fluorescent light, how many hours a day do I need to keep the lights on?

A: An absolute minimum for growth is twelve to fourteen hours per day. If youĂre pushing for bloom they will need about sixteen hours. Do remember that all plants need a period of darkness such as is provided in their natural habitat.

Q: What size pot is best to plant hoyas in?

A: That would depend entirely on how big the plant is that your planning to pot. If you are planting rooted cuttings, a 4÷ pot is usually sufficient for up to a year, or longer if itĂs a small growing plant. Pot sizes for plants that are being potted up to a larger size should be at least 1÷ but no larger than 2÷ larger than the root ball of your plant.

Q: What's the story on pruning hoyas..should we or shouldn't we?

A: An ˘old wives tale÷ that makes the rounds quite often, says ˘never prune hoyas or you will cut off the bloom spurs. That is partly true! You will cut off bloom spurs, however, the other part of the story is..when you prune (cut back) a plant, you will force many new branches and these new branches are usually loaded with new bloom spurs. Go ahead and prune your plants and be prepared for a bushier, prettier plant with lots of flowers.

Q: When is the best time of the year to repot hoyas?

A: Just as a plant is getting ready to go into a period of active growth (early spring to mid-summer) is an ideal time to repot. There may be times that for one reason or another you might have to consider repotting at some other time. This normally doesn't affect hoyas one way or another. They usually come through it with flying colors.

Q: Some books say to use phosphorus for flower production, others say potassium..which is correct?

A: Actually both of these elements help to promote flower production, however, all the fertilizer products on the market that claim to be ˘blossom boosters÷ have a higher middle number, which is always the phosphorus analysis.

Q: What is meant by the term ˘asexual reproduction÷ in plants?

A: The term asexual reproduction refers to the vegetative method of multiplying plants using parts of the same plant, such as by stem or leaf cuttings, or by planting bulblets, rhizomes or by dividing the plant itself.

Q: I have ten large hoya plants that have been in 8" baskets for over four years. I have never used fertilizers on them because I donĂt want them to get any bigger. They don't look very healthy anymore and a friend says they are suffering from a lack of nutrients. What does that mean and what are the symptoms of lack of nutrients?

A: Your friend is probably right! After four years in a pot most potting mixes would be pretty well depleted of any nutrients that your plants originally had access to. The chemical element that is depleted the fastest in any gardening, indoors or out, is nitrogen. The older leaves turn yellow or a very sick looking pale, grayish green and usually drop off in huge numbers. Any new growth is pale, stunted and often curled and distorted. A phosphorus deficiency shows up first in the leaf edges, tips and veins of a plant. These areas turn dull red or bronze beginning with the older leaves first. Any new growth is stunted or stopped entirely. The leaves will eventually turn a garish blue green, then purple mottled with brown and yellow. With a potassium deficiency the leaf tips and edges turn tan, bronze or sometimes even dull red, followed by crinkled, burned leaf edges. The leaf blades will turn yellow, beginning with the older leaves. New growth is stunted with shorter than normal distance between the leaves. These are the three main chemical elements that your plants need to help them manufacture their own food. When plants are severely deficient in any of these three components, it is safe to assume that all the other needed chemical elements are deficient also. If you have any halfway healthy looking growth still on these plants, I would recommend that you take some cuttings from these healthy parts and start some new plants. Then start a regular feeding program for your old plants, using a balanced fertilizer such as Peters 20-20-20 formula or any other good brand that has all the required trace elements included in its ingredients. Your original plants may not recover but if they are large and valuable plants itĂs always a good thing to at least try.

Q: The botanical names on some of these plants are real tongue twisters, is there a sensible reason behind some of these names?

A: Many botanical names are descriptive of a prominent part of a plant. Sometimes itĂs the foliage e.g. Hoya carnosa, which means fleshy or of fleshy consistency. Other names will refer to a description of the flowers e.g. Hoya pauciflora (few flowered) which usually has only one or two flowers. The flower parts e.g. Hoya pubicalyx (pubescent or fuzzy calyx), or maybe even a flower color e.g. Hoya purpureofusca (reddish brown flower). These descriptive names are often very helpful to taxonomists in identifying a plant, much more so than naming them in honor of a person or a place where they were discovered. The names really aren't that difficult if they are broken into syllables and pronounced slowly.

Q: What are the tiny little little black flies that fly around potted plants?

A: These are probably fungas gnats; they lay eggs in the potting mix. The eggs hatch out into tiny; almost microscopic worms that feed on the peat moss and often on the roots of your plants. A very small amount of a systemic pesticide watered into your plants every five weeks or so, will get rid of them.

Q: What is meant by a species being published?

A: In order to be a valid, recognized species a herbarium sheet with a dried 12 inch or so piece of the foliage along with the dried flowers must be sent to a herbarium complete with description in Latin and then published, or made public to a wide or varied audience..for instance through recognized botanical periodicals or bulletins.

Q: Do hoyas go dormant in the winter?

A: As with most tropical plants, hoyas don't go through a true dormancy, however, when temperatures drop accompanied by dark days with very little light, they will slow down and show no apparent activity until conditions improve. Plants that are grown under artificial lights, and with even temperatures continue to grow and even bloom through all seasons.

Q: Most of the tip ends of the new growth on my hoyas dies off. What causes this?

A: The three major causes of stem tip burn..and that's what it is!..(1) low humidity..(2) overfertilizing..(3)..stems touching a cold or hot surface. There are other causes but check into these first. My bet would be on overfertilizing along with low humidity.

Q: Do hoyas need a temperature drop at night?

A: Some hoyas definitely need a temperature drop at night to stay happy and bloom well. Others donĂt seem to care one way or the other. It apparently has a lot to do with their native habitat. Many hoyas live where the temperature seldom varies more than a few degrees between day and night..summer or winter.

Q: Where do most hoyas come from originally?

A: The largest number of hoya species have been collected in that vast area of the tropical world known as Indonesia. There are also numerous hoyas scattered through many of the South Pacific Islands as well as tropical and semi-tropical areas of India and China. Some species of hoyas with the largest flowers are from Australia.

Q: What are the symptoms of overfertilizing?

A: The first obvious sign is a buildup of fertilizer salts that rise to the surface of your potting mix in the form of white, crusty looking powder. In clay pots these salts are visible on the outside of the pot and around the inside rim close to the soil line. If this condition is not corrected by thorough leaching (rinsing out) of the potting medium, or a complete repotting, the roots will suffer severe chemical injury. The leaves of your plants will have dry, rusty, crinkled edges from chemical burns..and the main stem often swells and splits open near the soil line due to chemical injury of the plants plumbing system. This usually leads to the death of your plants.

Q: Where can I get hoya seed?

A: Hoya seed is not easy to come by. As far as is known, none of the hoya dealers have seed available. Sometimes there will be individuals who have a bumper crop of seed pods on their plants after a summer outside where they can be pollinated by bees, flies, moths or whatever. Your best chance for obtaining hoya seed would be to get acquainted with other hoya hobby growers.

Q: What is the best way to plant hoya seed?

A: There are special seed planting mixes available at most garden centers. Peat moss that is packed into nylon net and compressed into thin pellets that swell to the size of a 22÷ pot when moistened are known in America by the brand name of Jiffy 7 pellets, and are also excellent for planting seed. The immediate concern in growing plants from seed is to prevent the fungus that causes the damp-off disease which attacks seedlings at the soil line. Mix a solution of a good fungicide and use this mixture to dampen your seed mix or to activate the Jiffy 7 pellets. It is best to water your seed flats slowly from the bottom to prevent washing out the tiny seedlings before they are firmly rooted.

Q: What are the tiny white worms that are usually found on leaves along with aphids?

A: Aphids go through a gradual change from the nymph stage to the adult stage by molting or shedding their skins. As they grow, the skin does not grow with them but instead splits open and the aphids simply walk out of their old skin. Microscopic examination reveals that the ˘tiny worms÷ referred to here are actually the transparent skeletons, or mummies that are left behind by the aphids as they outgrow them.

Q: Sometimes when I water the plants in my greenhouse, centipedes will come scurrying out of the pots. Do they damage plant roots?

A: Centipedes are insect predators, and feed on beetles, grubs, slugs and snails that normally invade garden plants outdoors. Since centipedes don't usually hang around inside greenhouses and especially not down inside pots, IĂm wondering if the bugs you are seeing might not be symphilids or millipedes. These usually feed on decaying matter such as fir bark and peat moss but are not above eating large chunks out of plant leaves.


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