The publications in this collection do
not reflect current scientific knowledge
or recommendations. These texts
represent the historic publishing
record of the Institute for Food and
Agricultural Sciences and should be
used only to trace the historic work of
the Institute and its staff. Current IFAS
research may be found on the
Electronic Data Information Source
site maintained by the Florida
Cooperative Extension Service.
Copyright 2005, Board of Trustees, University
L. S. Osborne, R. W ei1y In EIR'T ha el
University of Florida IFAS
Agricultural Research and EBumtin'1Ceter \popka
AREC-A Foliage P1 nt Research Note RH-198 -L
.F.A.S. Univ. of Florida
Wax plant belongs to the genus Hoya, a member of the milkweed family,
Asclepiadaceae. Wax plants grown in the foliage plant industry are primarily
cultivars of one species Hoya carnosa. The preferred common name of the
species is wax plant, but wax vine and porcelain flower are occasionally
used. The fleshy leaves and flowers, which are covered with a semi-glossy
layer of waxy substances, account for the common names given to the group. A
few other species, such as H. australis, H. bella and H. multiflora, are
produced by a few nurserymen.
The wax plant is a semi-woody vine with nearly oval or ovate-shaped
leaves 2 to 3 inches long arranged oppositely along the stems. The flowers
develop in clusters 2 to 3 1/2 inches in diameter. The individual flowers
(florets) are attractive and consist of five white to pink symmetrical outer
lobes, about 5/8-inch across, and an inner structure which is red or partly
red. The inflorescences develop from the ends of spur-like branches along
the vines. These spurs increase in length slowly with each successive cycle
Wax plant is a minor foliage crop, constituting approximately one
percent of the total product mix grown in Florida. Although the plant is
well adapted to interiors with 125 foot-candles or more of light for
approximately 10 hours per day, it is not a favorite of many growers because
of its lengthy production schedule. It is most commonly grown in 3-inch
square pots, but a few producers offer 4-inch and larger pots. The plant is
most attractive when finished in hanging baskets which display the trailing
habit of the vines and the attractive flowers which appear periodically on
Wax plant is propagated from cuttings which are harvested from stock
vines. Normally single-node cuttings are made with a cut approximately 1/4
inch above each pair of leaves, leaving a longer stem section.below the
leaves to anchor cuttings which are usually direct stuck. Cuttings root in 3
to 4 weeks and a single shoot usually develops from one of the buds on each
cutting approximately 4 to 6 weeks later. Roots form along the stem section
below soil level with the greatest number of roots developing at or near the
node (point where leaves are attached to the stem). Cuttings should be
positioned so the node is at the soil surface to ensure maximum rooting.
Assistant Professor, Entomology; Professor, Foliage Extension Specialist;
and Associate Professor, Plant Pathology, respectively, Agricultural
Research and Education Center, 2807 Binion Road, Apopka, FL 32703.
Avoid sticking cuttings too deep as shoot development will be inhibited or
prevented if buds are positioned below the soil surface.
Wax plants develop best under l1ght intensities of 1500-2500 foot-
candles and temperatures of 68 to 75 F. Summer rooting and growth of wax
plant can be reduced if temperatures are excessively high due to poor venti-
lation or inadequate cooling. If greenhouses are run very cool in winter,
plants will become dormant. An acceptable production temperature range is 68
to 90 F.
After cutting material is harvested from stock plants, water management
becomes one of the most critical factors in propagation. As long as
greenhouse relative humidity is high (75 percent or more), the unrooted
cuttings should not be misted frequently. Simply apply enough water overhead
to keep the soil surface moist, not soggy. After roots develop to the bottom
of the pots, the watering frequency should be reduced to permit the potting
medium to nearly dry before the next irrigation.
Most wax plant growers prefer liquid fertilizer application over incor-
porated slow release products so the fertility level of the potting medium
can be adjusted as the crop irrigation frequency is changed. Fertilizers
with a 2:1:2 or 3:1:2 ratio with microelements added are a good choice.
Apply fertilizer at the rate of 2.8 pounds of nitrogen per 1000 square feet
Potting media should contain a high percentage of organic material, such
as fibrous peat, to provide good water holding capacity and some coarser
particles, such as pine bark, perlite and calcined clay to assure good
drainage and aeration. Several of the commercially available preblended
soilless mixes are suitable for growth of high quality wax plants.
Production schedules vary considerably depending upon cultivar,
temperature and degree of water management. The flat-leaf, all-green types
grow more than twice as fast as plants with variegated, reflexed leaves and
short internodes. It takes approximately 5 to 11 months to produce a
finished 3-inch pot of wax plant with a 6 to 8-inch long vine from an
unrooted, single-node cutting. One or two cuttings are stuck per 3-inch pot
and 3 to 4 single-node cuttings stuck per 4-inch pot.
There are several cultivars of Hoya carnosa which are grown by
commercial growers. Those cultivars of wax plant listed in the "1984-1985
Florida Foliage Locator" (1) are as follows:
Horticultural name Common name
Hoya carnosa Wax plant (
Hoya carnosa 'Argentea Picta' (P.P. 3307) Hindu RopeWa
Hoya carnosa 'Compacta'
Hoya carnosa 'Mauna Loa' (P.P. 3054) 'Lura-Lei'
Hoya carnosa 'Compacta Regalis' (P.P. 3306) Hindu Rop-'
oya carnosa 'Krinkle 8' (P.P. 3008) Krinkle 87
Hoa carnosa 'Krinkle 8 Variegata'
Roya carnosa 'Rubra' (P.P. 3105) Krimson Princess(
Hoya carnosa 'Tricolor' (P.P. 2950) Krimson Princess
Hoya carnosa 'Variegata' Variegated wax plant
Hoya purpurea-fusca 'Silver Pink' Silver pink wax plant
Hoya are relatively disease-free compared to many other foliage plants.
Since their leaves are thick and waxy, most fungal pathogens do not infect
them readily. Most diseases of Hoya occur when cuttings are in the rooting
process with leaves in contact with the potting medium and conditions are
wet and warm.
1) Botrytis blight (Botrytis cinerea)
Symptoms Botrytis infections are typified by large grayish areas on leaf
margins and sometimes centers. Tissue in the center of plants is
commonly infected since moisture levels in these areas are highest.
The dusty gray to tan spores of the pathogen form on infected and
dead tissue and can be easily seen with a 10 x hand lens. Affected
leaves collapse and turn mushy. This disease is primarily a problem
during the cool and relatively darker winter months in Florida.
Control Many plants other than Hoya spp. can also be infected with
Botrytis cinerea and control measures should be extended to all
susceptible hosts. Examples include lipstick vine, African violet,
English ivy and many flowering crops. Benomyl (Benlate) is registered
for control of Botrytis blight on ornamentals. Other fungicides which
are not registered for Hoya spp., but will control Botrytis blight are
vinclozolin (Ornalin) and iprodione (Chipco 26019). Reducing moisture
levels surrounding foliage by limiting water applications and increas-
ing air movement and therefore drying are recommended cultural controls.
2) Stem and root rot (Phytophthora, Pythium and Rhizoctonia'spp.)
Symptoms Stem and root rot on Hoya spp. sometimes goes unnoticed until
symptoms are quite advanced. This is probably due to the waxy nature of
the plant which retards wilting even when many roots are rotted.
Lesions on the stems are usually brown to black and can be mushy or dry.
Roots are gray to black and can also be mushy or dry. If plants are
infected with Rhizoctonia solani, leaves can also be infected and the
weblike red-brown mycelium of the pathogen can spread across the soil
surface and leaves.
Control Depending upon the cause of the stem or root rot, a- fungicide
may be chosen for control. Since symptoms caused by these organisms are
similar and fungicides used for their control differ, the exact
organisms involved in each disease must be accurately determined.
Pythium and Phytophthora spp. are controlled with soil drench applica-
tions of etridiazol (= ethazol, Truban) or etridiazol and thiophanate
methyl (Banrot). Rhizoctonia root rot can be controlled with soil
drench applications of Banrot or benomyl (Benlate). If both types of
organisms are involved in the disease, then applications of Banrot aid
in control. Reduce water applications to plants suspected of stem or
root rot disease and be sure to start with fresh potting medium, pots
and pathogen-free cuttings for each crop.
PHYTOTOXICITY OF FUNGICIDES USED ON HOYA CARNOSA
Chipco 26019 50WP Ornalin 50WP
Daconil 4.17F Subdue 2E
Fungo 50WP Truban 25EC
Pesticides were tested at recommended rates and intervals.
MAJOR INSECT AND MITE PESTS
The major arthropod pests of wax plants include aphids, fungus gnats,
mealybugs, mites, scales, and thrips. Mealybug, mite, and scale infestations
are typically the result of bringing infested plant material into the green-
house. Aphids and thrips have the ability to fly and thus invade the green-
house from weeds and other infested plants. In the control section for each
pest, a few of the many registered and effective pesticides will be listed.
For a complete listing, please consult the references at the end of this
report. Because of the numerous varieties grown in the greenhouse, a small
group of plants should be tested for phytotoxicity prior to treating the
entire crop. The list given in this section should be used only as a guide to
the sensitivity of this plant to pesticides.
Symptoms Aphids are pear-shaped, soft-bodied insects which vary in color
from light green to dark brown. The aphid most often observed feeding
on wax plants is the Oleander aphid, which is bright yellow with dark
brown appendages. Infestations frequently result from insects flying
into the greenhouse from infested milkweed or Oleander plants. These
infestations often go undetected until honeydew or sooty mold is
observed. Aphids can cause distortion of new growth or, in extreme
cases, infested plants will be stunted.
Control There are a number of materials that will control aphids; for
example, Orthene 75S, Vydate 2L, and Mavrik. Milkweed and Oleander
should be removed from around the greenhouse.
2) Fungus Gnats
Symptoms Small black flies are observed on the soil surface or on
leaves. The larvae are small legless "worms" that inhabit the soil.
The larvae spin webs on the soil surface which resemble spider webs.
Damage is caused by larvae feeding on roots, root hairs, and lower stem
tissues. Feeding damage may predispose plants to disease.
Control Reduce the amount of water applied to each pot where possible.
Soil drenches and soil-surface sprays with Vydate 2L will effectively
control the larvae.
Symptoms Mealybugs appear as white cottony masses in leaf axils, on the
lower surfaces of leaves and on roots. Honeydew and sooty mold are
often present, and infested plants become stunted and, with severe
infestations, the plant will die.
Control Systemic materials are preferred. Examples of chemicals which
have systemic activity are: Dimethoate, Disyston, Metasystox-R, and
Orthene. Bendiocarb appears to be as effective as some of the systemic
materials. Control of root mealybugs is accomplished with soil drenches
with an insecticide. Diazinon and Vydate are the only insecticides
registered for this purpose, but both can cause some phytotoxicity.
When pesticides are applied to the soil, care must be taken to assure
that the pots have good drainage and that no saucers are attached or
phytotoxicity may result. Prevention is the best control. Plants
should be grown in clean soil and pots on raised benches.
Symptoms This plant is attacked by broad mites, which are very small
and go usually unnoticed until plants become severely damaged. Terminal
growth is the preferred feeding site and causes the inhibition of new
growth, necrosis of the vegetative shoot apex, followed by abscission of
affected plant parts.
Control Kelthane and Pentac are effective controls for broad mites. The
critical point in any control program is thorough coverage with the
pesticide. The best control program is prevention by minimizing the
possibility of introducing mites into the growing area.
Symptoms Infested plants become weakened or stunted and die. Scales can
be found feeding on leaves, petioles, or stems. Their shape, size, and
color are variable and many are hard to distinguish from the plant
material on which.they feed.
Control See Mealybugs
Symptoms Infested leaves become curled or distorted, with silver-gray
scars or calloused areas where feeding has occurred.
Control Many materials are registered and effective at controlling
thrips such as Vydate 2L.
PHYTOTOXICITY OF INSECTICIDES AND MITICIDES TO HOYA CARNOSA
Pesticides were tested at recommended rates and intervals.
1. Anonymous. 1984-1985 Florida Foliage Locator. Florida Foliage
Association. 160 pp.
2. Chase, A. R. 1983. Phytotoxicity of some fungicides used on tropical
foliage plants. ARC-Apopka Research Report, RH-83-2.
3. Short, D. E. 1978. Phytotoxicity of insecticides and miticides to
foliage and woody ornamental plants. Extension Entomology Report #57.
4. Short, D. E., L. S. Osborne, and R. W. Henley. 1983. 1983-84 Insect
and related arthropod management guide for commercial foliage and woody
plants in Florida.
5. Simone, G. W. 1983. Fungicides for use on ornamentals 1983-84.
Extension Plant Pathology Circular 484-B.
Mention of a commercial or proprietary product or of a pesticide in this
paper does not constitute a recommendation by the authors, nor does it imply
registration under FIFRA as amended. Pesticides should be applied according
to label directions. Those pesticides listed in the control sections for each
disorder, but not listed in the phytotoxicity charts HAVE NOT been tested for
plant safety.at the University of Florida.