Pictures of gardenia plants

Gardenia Plant Diseases: Learn About Common Gardenia Diseases

The brilliant white blooms of the gardenia are only their second best feature – that heavenly smell they produce fills the air with a scent like no other. It’s no wonder that gardeners are extremely protective of their gardenias! Unfortunately, even the most pampered plant may develop one of the common gardenia diseases. This handy guide will arm you with the knowledge to properly care for your favorite plant.

Common Diseases of Gardenia

Most common diseases in gardenia plants are caused by fungus and easily prevented by creating a well-draining environment with good air circulation. Proper watering and pruning further helps to keep gardenia plant diseases in check. Among the most common diseases of gardenia are root rot, powdery mildew, stem canker and bud drop. Treating gardenia problems like these is a task most gardeners can handle.

Root Rot

Root rot is common in plants that are chronically over-watered or are growing in poorly draining soil. A variety of fungal pathogens take advantage of the stressed plant and destroy root tissues, causing them to turn brown, black or mushy. You may notice that your plant is yellowing, with the oldest leaves affected first – it can come on gradually or cause a sudden widespread wilt in your gardenia.

You can often save plants with root rot by digging them, pruning away damaged roots and replanting them in a spot with better drainage. Be careful to only water when the top two inches of soil feel dry to the touch to prevent future problems.

Powdery Mildew

Powdery mildew results when air circulation is poor, allowing humidity to build around dense bushes or tree canopies. Unlike other fungal diseases, standing water isn’t necessary for powdery mildew spores to germinate, but they can’t survive without constantly humid conditions. Powdery mildew causes a distinct white, fuzzy or powdery coating on leaves and deformation of new growth.

Neem oil is very effective control, but you should also consider thinning the inside of your gardenia to allow for better air circulation. If your gardenia is potted or indoors, move it away from structures and other plants. Powdery mildew isn’t serious, but a chronic case can drain a plant, allowing other pathogens to invade.

Stem Canker

Stem canker only affects a small percentage of gardenias yearly, but it’s a serious disease that every grower should be aware of. These dark, oval lesions are caused by the fungus Phomopsis gardeniae when it manages to gain access through wounds. Galls may form on affected branches, but more often, widespread wilt is seen. The plant may stunt or drop leaves and buds, depending on the seriousness of the infection.

The only control is to remove the affected stems, cutting back well into healthy tissues. Disinfect your pruners between cuts to prevent spreading the disease further. As with other fungal diseases, increasing drainage, taking more care in watering and increasing air circulation can help prevent recurrence.

Bud Drop

Bud drop appears in stressed gardenias, but can be baffling to gardeners who have never seen it before. As the name implies, the primary symptom is bud and flower failure – they simply drop or dry up with few other clues. Pests and environmental problems are to blame for this common problem – check your plant carefully for tiny bugs and treat accordingly. Additionally, sooty mold can be seen on plants affected by insect pests, like aphids. Treating the pests will normally take care of the fungus. Neem oil works well for both.

If no insects are present, you may need to adjust your watering habits, fertilize more carefully or provide better protection from sudden cold spells.

Summary: Below is a series of Gardenia problems homeowners may experience.

Gardenia Leaves Turning Yellow

The Gardenia plant (Gardenia jasminoides) produces fragrant flowers and handsome foliage making it a great addition to any garden. However, maintaining gardenias is not an easy task and mishandling would put it at risk of dying. Yellowing and dropping of Gardenia leaves have several possibilities… from a nutritional deficiency, low humidity and overwatering.

Yellowing Leaves From Nutritional Deficiency

1 – If you plant has a magnesium or iron deficiency, growth may become retarded along as the leaves turn yellow or discolored.

2 – Gardenias in need of fertilizing, will exhibit symptoms of no buds or dropping buds, gardenia yellow leaves spots or yellowing at outer leaf edges and moving inwards, pale bleached look, dropping older leaves.

Same as above – If there are no flowers or buds – feed the acid-loving plants with an acid gardenia fertilizer. No feeding while the tree blooms or during winter.

Massive Leaf Drop and Yellowing Leaves

Yellow leaves on gardenia in mass followed my leaves dropping, the problem often is watering – Too Much water.

If leaf curl, gardenia leaves turning brown, dieback occurs and the soil is constantly wet. The plant should be removed from the pot immediately. Check the root ball for health, make sure pot drainage holes are not plugged.

Checking The Roots:

  • White healthy looking roots – remove all bad foliage, place back in the pot and fix watering issues or repot into fresh new soil.
  • Roots damaged and partially brown – remove bad roots, repot in fresh soil
  • Roots mushy and brown – discard plant

Gardenia Leaves Yellowing From Low Humidity

The symptoms of low humidity show up as: flower buds dropping, leaf tips turning brown, yellowing foliage, gardenia flowers turn brown.

Place the potted gardenia in a tray or bed of moist pebbles. DO NOT allow the pot and roots to sit in water. Spray/mist once or twice per day. In winter use a humidifier.

Gardenia Bud Drop

Question: The buds on my gardenia plant get about ready to open, then start to turn brown. What can I do to make them bloom?

Answer: This trouble is referred to as bud drop. The proper culture to prevent bud drop is difficult in a house and often occurs in spite of all precautions in a home greenhouse.

Frequent overhead watering after the buds are set may cause them to drop, but lack of sunlight is the chief cause of bud drop. With a uniform temperature of 60 to 62 degrees, good light, and high humidity, the chances of bud drop are slight.

A pot-grown gardenia should have a regular application of one ounce of iron sulfate to two gallons of water at least once a month to maintain correct soil acidity.

An alkaline soil condition will prevent the buds from opening and is one cause of bud drop. If unsure of the soil pH, gardeners usually conduct a soil test.

New Plant Bud Drop

If the buds on a new gardenia plant turn to black and drop off the issue could be all environmental. Plants moving from a nursery environment to a garden center and then to the home could “shock” the plant as it is acclimating to new surroundings: low light, warm temperatures in the home, low humidity can all contribute to bud drop.

Spray-mist on a daily basis, place plant on a tray of pebbles to increase humidity.

Sooty Mold

Question: I have three large gardenia bushes, about 12 years old. This year there is a black mold on the leaves. How can I rid the bushes of it? CAE, Texas

Answer: One “type” of sooty mold is caused by an airborne fungi. These pests usually appear when plants are chilled or wet frequently and not properly ventilated. Better light, more air, and keeping the foliage dry when watering is the best preventative. A light spray using oil emulsion such as Volck diluted one to 75 will destroy sooty mold fungi on gardenia bushes.

Question: What causes a sooty, black film on the leaf surface of gardenias?

Answer: This is the “other type” of sooty mold. This sticky secretion on gardenias is caused by whiteflies which may be controlled with a horticultural oil emulsion spray.

Syringe plants with water a few days after to wash off the dirty film. Privet and lilac are also attacked by these pests. Other pests that may infest the gardenia plant include spider mites and aphids.

Related Reading: Getting Rid Of Sticky Leaves On Houseplants

Water & Spraying

Question: I was told that a gardenia plant needs to be watered every other day and sprayed once a week with malathion. What fertilizer suits it best and how much should be applied and how often? Should it get sun or shade? TZ, Mexico

Answer: The gardenia is a sun lover but some shade during the hottest part of the day is not harmful. It needs water often enough to keep it from getting really dry when growth is active but probably not every other day.

A weekly forceful spray of water with occasional sprays of malathion should keep the plant clean and free of insects. If your plant is outdoors, a 2-inch layer of peat moss and rotted cow manure over a well-drained soil is advantageous. For healthy gardenia plants, keep the soil moist but don’t over water to avoid root rot.

If confined in a container, a 5-10-5 slow-release fertilizer could be used either dry at the rate of a level teaspoonful to a 6-inch pot or as a liquid at the rate of 2 teaspoonfuls stirred in one gallon of water. Food may be given the plant about every three weeks when growth is active.

Propagation

Question: Could you tell me how to start a new gardenia from an old one?

Answer: Tip cuttings three or four inches long are taken late in the winter and rooted in a mixture of sand and peat. Insert unrooted cuttings in 2-1/2-inch pots, and give them a bottom temperature of 70 to 75 degrees.

If kept moist and in an atmosphere that is not dry, the cuttings will root in about eight weeks.

Normally, gardenias grown outside are attacked by only a few insects and one serious disease.

Gardenia Pests

When gardenias are attacked by root-knot nematodes, the leaves become chlorotic.

These microscopic worms produce characteristic galls or swellings on the roots. Prevention consists of soil sterilization before planting but using steam or chemicals.

Care should be taken when using any chemical materials since they will kill plants (people too) when used too close. Once the plants are infested they should be destroyed as there is no cure.

Scale

The scale insect is the most common pests attacking gardenias grown outdoors.

Whiteflies and mealy bugs sometimes attack gardenias, too. The black vine weevil rarely causes trouble but is serious when it does.

Thrips can also be bothersome, especially when gardenias are grown near a field of weeds.

Black scale can be a real pest. Each scale is about the size of a small split pea, dark brown to black and nearly hemispherical with a conspicuous H-shaped marking on the back.

The honeydew secreted attracts fungi which in turn give the leaves and stems a black, sooty appearance. This also attracts ants which help spread the scale.

In Florida and the Southeast the scale pest is the Florida waxscale, reddish or brown and the size of a pinhead.

Orthezia sometimes attacks gardenias grown outdoors; they are small, long and white, with long stripes on their backs. You will need a hand lens to see them.

All the scales are sap-sucking and some inject a poison. The soft brown scale can be a serious pest at times. too. It is greenish brown, oval-shaped, rather flat and about 1/8 inch long. It infests leaves and limbs and produces a honeydew as does the black scale.

The treatment for all scale is a summer oil spray applied at two-week intervals using a 2 percent oil, Malathion can be used as well but I prefer oil.

Water plants well one half-hour before spraying and again syringe with water an hour after spraying.

Thrips

Thrips and the tobacco thrip are also common gardenia pests. Injury is manifested by a silvering of the leaf because the thrips suck the plant juices. You will need a hand lens to see them on the underside of the leaves as they are very small flying insects.

Clean up all weeds which harbor them.

Mealy Bug

The citrus mealybug is usually found on greenhouse gardenias, but sometimes attacks those grown outside.

A hard, sharp syringing with a small spray of water usually keeps them under control in many vegetable gardens. Otherwise, use a 2% percent summer oil and a teaspoonful of Malathion to each gallon of water.

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White Fly

Whiteflies are quite small, about 1/16 inch long. The adults are pure white and when disturbed fly away from the underside of the leaf where they feed. The larvae look like very small mealy bugs. Both adults and immature stages are found together. For outdoor control use organic neem essential oil sprays (natural) or Malathion (chemical).

Red Spider Mites

Tiny red plant spider mites sometimes attack the plants in late summer, especially when the air gets – hot and dry. You will need a hand lens to see the reddish spider mites which can be controlled by regular hard syringing with cold water.

Do not become alarmed by our mention of all these insects – your plants may never be attacked by any of them but it is best to be aware of them if they do.

Gardenia Pest Management

There are plenty of natural ways you can use to get rid of gardenia pests. One of the most effective and safest ways is by making use of diatomaceous earth or food grade DE. This natural pest control substance help eradicate a wide array of insects.

Some essential oils such as neem oil help solve common pest problems. Peppermint oil wards off squash bugs, parasitic wasps, mites, tomato hornworm caterpillars, beetles and more. On the other hand, cedarwood, hyssop and pine essential oils keep slugs and snails away from your gardenia plants.

Introduction of beneficial insects that feed on vegetable garden pests will also help solve the infestation.

Gardenia Diseases

The one disease most often found is phomopsis canker, a fungus disease (ficus trees get this as well).

The first symptom of this disease will be a shrinking of the stem at the soil line. This gradually enlarges and the whole stem swells and becomes rough and cracked.

The leaves become pale green, then yellow and many fall. Since the disease enters plants only through wounds, use all possible care not to injure the stem when planting or pruning. There is no known cure so dig and destroy (burning is best) infected plants.

Leaf Spot On Gardenia

There 2 possible causes for leaf spots on gardenias. One is Bacterial Leaf Spot which is caused by bacteria–either Pseudomonas or Xanthomonas. Bacteria causes small, round ovoid spots on young, tender leaves. As the spots enlarge, the center is at first pale yellow and later becomes reddish-brown surrounded by a yellow halo. Margins of the lesions are thickened and water-soaked in appearance. Spots may coalesce to form large, irregularly shaped spots. Severe infection may cause defoliation. To control, avoid overhead watering.
The second common problem is Leaf Spot caused by the fungi–Cercospora or Phyllosticta. These fungi cause spots of various sizes on leaves throughout the year. Spots may be small, dark-brown necrotic areas surrounded by a yellow halo. In severe cases, premature leaf drop may occur. Control is obtained by spraying with a foliar fungicide. You can cut off the affected leaves to keep the problem from spreading or you can use a fungicide on your plant to prevent the disease from spreading to new leaves.
In either case, the damage that has occurred is irreversible. You will want to remove and properly dispose of affected plant parts.

Gardenia Diseases & Other Problems

With their wonderfully fragrant blossoms and lustrous, dark green leaves, gardenias (Gardenia angusta, previously known as G. jasminoides) are popular shrubs with many southern gardeners. Their positive qualities compensate to a large extent for the fact that gardenias are somewhat high-maintenance plants with fairly specific cultural requirements. To learn more about growing healthy gardenias, see HGIC 1065, Gardenia. In addition to problems resulting from improper growing conditions, gardenias are also susceptible to several diseases, insect pests and other problems. For information on insects and related pests that attack gardenias, see HGIC 2059, Gardenia Insects & Related Pests.

Diseases

Gardenia (Gardenia angusta) exhibiting above-ground symptoms of root rot.
Steve Jeffers, ©2009 Clemson Extension

Root Rots: Various fungi, including Phytophthora species, Rhizoctonia species and Pythium species, cause root rots in gardenias. In South Carolina, Phytophthora is identified most often as the pathogen. As the disease name indicates, root rots are characterized by a decay of some portion of the roots.

Above-ground symptoms of root rot include leaf yellowing (oldest leaves first), leaf drop and wilting. Depending on how extensively the roots are affected as well as which roots are affected, the plant may appear generally unhealthy for an extended period of time, or wilt suddenly and die. In addition, the symptoms may be present on only one side of the plant or may affect the plant as a whole.

When above-ground symptoms indicate root rot, roots should be examined as soon as possible. A healthy root system will have white feeder (non-woody) roots present. With root rots, the feeder roots may be brown and rotting, or missing completely. The outer tissue (cortex) of rotting roots can be easily removed by pulling, leaving behind the threadlike core or stele (conducting tissue).

Disease development is favored by any factor that encourages wet soil conditions, including poor drainage and over irrigation. Planting too deeply also contributes to the problem.

Control: The best management practice for root rot problems is prevention. Check the roots of nursery stock before purchasing. Make sure there is adequate drainage in the area where you want to plant. If the area drains poorly, creating a raised bed can help.

If a plant has already died from Phytophthora root rot and a replacement is wanted for the same location in the landscape, it is best to choose a plant that is known to have resistance.

Powdery Mildew: The fungus, Erysiphe polygoni, causes powdery mildew on gardenias. Fungi that cause powdery mildew typically grow on the surface of a plant sending only their haustoria (specialized organs for absorbing nutrients and water) into the plant cells.

Signs of infection include a whitish to grayish colored, powdery, fungal growth that can occur in spots or patches, which sometimes enlarge to cover the entire leaf or other plant structure. The fungus is mostly found on the upper leaf surface, but also may be found on the lower leaf surface. The disease typically appears in the summer and reaches its peak in late summer. Over time, these patches of fungal growth may darken and form small, rounded, reproductive structures called cleistothecia. They begin as pinhead-sized, round structures that are whitish and then darken to yellow-brown and finally to a brown or black color.

Powdery mildew of gardenia primarily affects young leaves and shoots, and symptoms of infection typically include deformed leaves and buds, leaf yellowing, and leaf drop.

Control: Properly space plants to allow for good air circulation which reduces the humidity level needed by the fungus to infect. Prune out diseased tissue, and rake up and destroy fallen leaves.

If needed, apply fungicides as a preventative against powdery mildew. Fungicides are most effective against powdery mildew when used early in the disease development process. Recommended fungicides include myclobutanil, thiophanate-methyl, chlorothalonil, propiconazole, triforine and horticultural oil with baking soda. Some control may also be obtained by applying sulfur or neem oil. See Table 1 for products.

Canker on main stem of gardenia (Gardenia angusta).
Joey Williamson, ©2010 HGIC, Clemson Extension

Stem Canker: In general, cankers are dark, oval or elongated stem lesions that may be sunken with a raised edge. With time, the canker may develop into a gall (a swollen area resulting from infection). Cankers are most often found on stems (especially near soil level) of a gardenia; however, leaves and roots are also susceptible. They are caused by the fungus, Phomopsis gardeniae, which gains access to the plant through wounds. The fungus remains localized near the canker and with high humidity will produce spores that are easily spread by rain or overhead irrigation. The fungus survives the winter within the canker.

Depending on where the canker develops, the first symptom that often is noticed is wilting of the leaves on part or all of the plant. Leaves on affected branches often become a duller green color, may yellow and then drop. Flower buds on affected branches may drop without opening. Overall stunting of the plant is common.

Control: The most important aspect of controlling this disease is to prevent injury to the gardenia. Infected stems should be pruned out, taking care to disinfect pruners in a 10% bleach solution (1 part bleach to 9 parts water) or 70% alcohol solution between cuts. Avoid stressing an affected gardenia further by over- or under-fertilizing, or over- or under-watering. Irrigate at the base of the plant to minimize moisture on plant surfaces as well as spread of spores. Affected plants that are growing poorly should be removed and destroyed. Any new gardenias should be planted in a different location. In a home landscape, fungicides are generally not practical or effective control options.

Galls on roots infested with root-knot nematodes (Meloidogyne spp.).
Clemson University – USDA Cooperative Extension Slide Series, Bugwood.org

Nematodes: Various nematodes (microscopic roundworms) feed on the roots of gardenias. Above-ground symptoms of root damage resulting from nematode feeding include wilting during hot, dry weather, oftentimes with recovery at night. Leaves may show yellow mottling and other indications of a nutritional deficiency. Over time the plant may become stunted and exhibit dieback of branches.

Below-ground symptoms depend on which nematode species are feeding as well as how many are feeding. Root damage can include stunting, discoloration, excessive branching and/or the presence of galls (small swellings of plant tissue).

Control: To confirm the presence of nematode damage, root and soil samples should be tested. Depending on the amount of root damage, gardenias may benefit from more frequent applications of water and fertilizer. In addition, mulching is helpful. Severely affected gardenias should be removed and destroyed.

There are no nematicides available to homeowners for treating the soil to control nematodes. If nematodes are a problem in a particular area, plant in a different location or choose a plant that is resistant to the nematodes present.

Other Problems

Sooty mold present primarily on previous year’s foliage.
J. McLeod Scott, ©2010 HGIC, Clemson Extension

Sooty Mold: A charcoal-black, powdery or velvety coating on leaves and other plant parts is the result of growth of one of the commonly occurring sooty mold fungi. The good news is that despite its appearance, the fungus is not infecting plant tissue and is not causing disease. It grows on the surface of the plant and gets its nourishment from honeydew that is excreted by sap-sucking insects such as aphids, some scales, whiteflies, leafhoppers, mealybugs and others. As these insects suck plant sap, they are unable to digest all of the sugar that they ingest. The excess is excreted as sugary liquid called honeydew. For information on controlling the insect pests whose feeding habits result in sooty mold problems, see HGIC 2059, Gardenia Insects & Related Pests.

Diagnosis of sooty mold is made simple by the fact that the black fungal growth can be removed by wiping with a moist paper towel, or in some cases, by peeling it off to reveal an undamaged plant surface.

While mainly a cosmetic problem, when sooty mold is severe it can reduce the vigor of plants by blocking sunlight necessary for photosynthesis (food production). On the other hand, insect feeding can seriously damage a plant. Between insect feeding and reduced photosynthesis, the plant may be more susceptible to other insect, disease, and environmental problems.

Control: Since the cause of the problem is insect activity, control measures should be directed at the insects rather than the fungus. Important first steps include identifying the plant that is infested and the insect that is causing the problem. When identifying the infested plant, always look at plants growing above the gardenia as well as the gardenia itself. With a sufficiently heavy infestation of sap-sucking insects, the sticky honeydew may drip from an infested plant to non-infested plants growing below (as well as onto objects such as lawn furniture, decks, cars, etc.).

Bud Drop: When a gardenia is stressed, unopened flower buds may drop from the plant. Potential stressors include infestations of thrips or aphids, root feeding by nematodes, too much fertilizer, over-watering, under-watering, poor soil drainage, insufficient light, unusually cool weather, rapid drops in temperature or very hot, dry weather.

Yellowing Leaves: As an evergreen shrub, it is normal for older leaves of a gardenia to turn yellow and drop. This typically occurs during early spring before new growth appears. If chlorosis (leaf yellowing) occurs at other times of the year and there is no evidence of insect pests or disease, and the remaining leaves look healthy, then there may be an environmental or cultural factor causing yellow foliage. As with bud drop, several stressors, including insect infestations, nematode feeding, over-watering, under-watering, poor soil drainage, insufficient light, soil temperatures below 70 °F and poor nutrition may cause leaf yellowing and drop.

Gardenia (Gardenia angusta) exhibiting iron chlorosis (yellowing between the veins) on newer foliage.
Meg R. Williamson, ©2010, Plant and Pest Diagnostic Clinic, Clemson University

Iron Chlorosis: Gardenias are acid-loving plants that grow best in a soil with a pH of 5.0 to 6.0. Iron is an essential nutrient that plants use to produce the green pigment, chlorophyll. While iron is rarely deficient in soil, if the soil pH is above 7.0, the iron may be in a form that is not available to the plant.

When a gardenia does not get the iron it needs, its leaves generally turn pale green to yellow. Young leaves may turn completely yellow except for the veins and nearby tissue which remain green. Older leaves may only be yellow along the edges. Overall, the plant may become stunted.

Control: Ideally, soil pH problems are corrected prior to planting. Since this option is often not available, the first step for solving a suspected iron deficiency problem is to take a soil test to determine the soil pH. If the existing pH is identified as being too high, instructions are provided in HGIC 1650, Changing the pH of Your Soil on how to lower soil pH as needed.

In cases where the soil pH was raised above 7.0 due to the application of lime, water soluble sulfur or aluminum sulfate can be applied to the soil beneath the shrub. However, in soils with a naturally high pH, applications of these materials may not result in a permanent lowering of the soil pH.

In lieu of changing the soil pH, annual applications of chelated iron can be applied to the soil or directly to gardenia leaves to provide the necessary iron. Another iron source that can be used for foliar applications is ferrous sulfate (FeSO4·2H2O). When foliar applications are used, the addition of a couple of drops of dishwashing soap per gallon of water will help wet leaves and aid absorption. These soil or foliar applications will have to be applied multiple times during the growing season if the underlying soil pH problem is not resolved. Reapplication time should be determined by observing the leaves for the reappearance of symptoms. See Table 2 for brands of iron-containing products.

Once the soil pH has been corrected, it can be maintained by using a slow-release fertilizer that is designed for acid-loving plants, such as Vigoro Premium Azalea, Camellia & Rhododendron Food (10-8-8); Scotts Evergreen Flower, Tree & Shrub Continuous Release Plant Food (11-7-7); Lilly Miller Azalea, Camellia & Rhododendron Food (10-5-4); Hi-Yield Azalea, Camellia, Gardenia & Evergreen Fertilizer (4-8-8); or Espoma Holly-tone (4-3-4). Also, be sure not to apply lime near a gardenia. Keep in mind that lime can leach from cement and brick mortar and affect the pH of the surrounding soil.

Table 1. Fungicides for Gardenia Disease Control.

Pesticide Active Ingredient Brand Names & Products
Chlorothalonil Hi-Yield Vegetable, Flower, Fruit & Ornamental Fungicide Concentrate
Ferti-lome Broad Spectrum Landscape & Garden Fungicide Concentrate
Ortho MAX Garden Disease Control Concentrate
Bonide Fung-onil Concentrate
Tiger Brand Daconil
Southern Ag Liquid Ornamental & Vegetable Fungicide
GardenTech Daconil Fungicide Concentrate
Horticultural oil1,2 Ferti-lome Horticultural Oil Spray Concentrate
Bonide All Seasons Spray Oil
Southern Ag ParaFine Horticultural Oil
Monterey Horticultural Oil Concentrate
Summit Year Round Spray Oil Concentrate
Myclobutanil Spectracide Immunox Multi-Purpose Fungicide Concentrate; & RTS3
Ferti-lome F-Stop Lawn & Garden Fungicide Concentrate
Monterey Fungi-Max
Neem oil Southern Ag Triple Action Neem Oil Concentrate
Ferti-lome Rose, Flower & Vegetable Spray Concentrate
Garden Safe Fungicide 3 Concentrate
Garden Safe Neem Oil Extract Concentrate
Monterey 70% Neem Oil Fungicide/Insecticide/Miticide
Bonide Neem Oil Concentrate
Natural Guard Neem Concentrate
Propiconazole Ferti-lome Liquid Systemic Fungicide II Concentrate; & RTS3
Bonide Infuse Systemic Disease Control Fungicide Concentrate; & RTS3
Banner Maxx Fungicide
Sulfur2 Southern Ag Wettable or Dusting Sulfur
Bonide Sulfur Plant Fungicide (also wettable for spray)
Hi-Yield Wettable Dusting Sulfur
Safer Brand Garden Fungicide Concentrate
Thiophanate-methyl Cleary’s 3336 WP Turf & Ornamental Fungicide
Southern Ag Thiomyl Systemic Fungicide
1Add 3 tablespoons of horticultural oil to a gallon of water with 3 tablespoons of baking soda for powdery mildew control.
2Never apply a horticultural oil spray within 2 weeks of a sulfur spray, and do not apply horticultural oils or sulfur when the temperature is above 90 °F or to drought-stressed plants.
3RTS = Ready to Spray (hose-end applicator)
With all pesticides, read and follow all label instructions and precautions.

Table 2. Iron-containing Products to Correct Iron Chlorosis in Gardenia.

Brand Names & Products Containing Iron Percent Iron & Comments
Ironite Mineral Supplement (1-0-1) 4.5% iron, plus 6 other trace elements; granules
Southern Ag Iron Granules 20% iron from ferrous sulfate; granules
Hi-Yield Copperas 19% iron from ferrous sulfate; granules
Southern Ag Essential Minor Elements 5% iron from ferrous sulfate & chelated iron, plus 7 other trace elements; granules
Southern Ag Chelated Liquid Iron 5% iron (chelated) for soil application or foliar spray
Hi-Yield Liquid Iron & Other Micronutrients 2.5% iron from ferrous sulfate for soil application or foliar spray, plus 3 other trace elements

The Worst Place For Your Gardenia

Steve Bender

Like most of you, Grumpy loves a gardenia. If there is a plant on Earth whose flowers emit a more powerfully sweet scent, I haven’t smelled it. Thus, I have a gardenia in my yard, my next-door neighbor does too, as does just about everybody else up and down the street.

From observing this, I have come to the following conclusion. There are many places to plant a gardenia, but the absolute worst is right in front of your house. The photo above shows the reason.

A gardenia bush typically opens its main flush of blooms over several weeks in late spring and early summer. Flowers unfurl alabaster white into perfectly shaped corsages. The problem is, blooms don’t stay white for long. After a week or so, the oldest blooms turn yellow and then brown and remain on the shrub even as new flowers open. The photo reflects the result. Is the gardenia half-alive or half-dead? It doesn’t really matter—it’s not an attractive sight and surely not one you want to occupy a featured spot in front of the house.

You could pick off the blooms as soon as they start to fade, but who really does that? A really bored person, that’s who. Thus, it behooves all of us to select a place for gardenia where we don’t have to do that—maybe the backyard, the side yard, or a courtyard. Any place but out front. That way, we get to enjoy the weeks of perfume without worrying that the neighbors think we don’t take pride.

WATCH: Grumpy Gardener’s Guide to Gardenias

I’m sure many of you reading this already have gardenias planted out front. No need to feel ashamed and wear bags over your heads. You can always move the plants to a better spot this fall. Or don’t. But if you choose the latter, be prepared to field questions like this: “Why is your gardenia dying?”

General Information on Gardenia Plants and Their Species

Images of gardenia plant and pictures

Having a gardenia flower at home is what practically everyone dreams of. Why? It really amazes everyone with its colorful blooms and fragrant scent. You can find the images and pictures and ascertain it’s true. However, being very tender and finicky, these plants require a lot of attention. So, knowing basic care instructions is essential.

Today gardenias are considered to be a perfect choice for a beautiful bonsai. They make a big impression, only if one knows how to care for gardenia. Generally speaking, it is highly important to plant it near a window or deck, where you can always enjoy its fragrance. The flower grows from 2 up to 8 feet wide and tall, though lots of things depend on the variety.

Many flowers grow into a round shape and have glossy, dark green leaves and fragrant white flowers, which bloom from spring to summer. Forget about planting them near a foundation or concrete wall, as the pH level there is too high for perfect growth.

Gardenia Care Guide: Tips and Recommendations to Follow

Care for gardenia is a special aspect to pay attention to, as these flowers are cold sensitive and may die during winter time. That’s the primer reason why they are mainly grown outdoors only in places where winter months are tolerable. At times they are placed into pots and moved in for winter.

Speaking about the main rules of outdoor caring for gardenia, it is highly important to keep in mind that these bushes prefer being kept in partial shade. They also like moist and well-drained acidic soil. Regular watering is of primer importance during cultivation, even after the plant finished putting out its blooms. After the flowering ceased, start pruning the bush to keep it in a good condition. When the bush is healthy, it’s much easier for it to withstand winter weather.

There are many species and types of gardenia like star, jasminoides, thunbergia, etc. The indoor growing of these bushes can be quite successful as well. However, it should be pointed out that they require high humidity and bright light, when indoors. The most troublesome days for them are winter days, meaning their dryness doesn’t provide enough humidity, which becomes a real problem. If you face the same problem, move the tree to south-facing windows and supplement them with grow lights to improve light condition.

Dry air triggers flower dropping, and to increase humidity you should use a humidifier or you can group the plants on trays of wet pebbles. Don’t mist them to avoid possible problems with fungal leaf spots and yellow leaves.

Make sure the soil is organic and loose. It must be moist, but don’t be too enthusiastic not to overwater it. Monitor it on a regular basis and water it regularly, when you see that the top is already dry. The plant that is inside your house should always receive cool night time and warm daytime temperatures.

Basic Growing Tips. What You Should/Shouldn’t Do

As it has already been mentioned, these bushes like humidity a lot, and misting the leaves quite often causes a number of problems. Water droplets lead to the appearance of leaves with fungal growth. This is mainly the problem faced by those, who plant the flower outside. Never place it under the plants that may drip into its leaves and make sure that they aren’t placed too close together, because lack of air leads to occurrence of fungal problems.

Always check whether the top inch of the soil is dry (just poke a finger) to know when it is necessary to give your plant a good soak. Drain out the water that normally accumulates under the pot. The best way out is growing the flower in a pebble filled tray: water can be poured over the pebbles, thus ensuring enough humidity and moisture without any excessive liquid being absorbed into the soil.

We’ve already mentioned that the knowledge on how to grow these bushes is connected with enough light they get. Outdoor plants prefer sun combined with shade during hot summer days. Indoor ones mustn’t be placed in direct sun, but in a room that receives much bright, but indirect sunlight.

Gardenia Diseases and Pests to Be Concerned About

Gardenia problems are what every gardener faces, while picking this flower one of the main in his garden. Diseases and pests are common today, and though coping with them may be a very hard task to do, it is still possible.

Perhaps one of the best ways to protect the bushes is to keep them healthy and do everything possible to prevent over-crowding. If you allow too much moisture to sit on leaves and do not maintain proper moisture and temperature levels, you cause the appearance of insect problems. To the commonest insects these plants are vulnerable to belong:

  • scale
  • aphids
  • thrips
  • mealy bugs
  • whiteflies
  • spider mites

Among the most serious malums there are:

  1. Leaf spot. Fungi trigger the occurrence of spots of different sizes. They may be small or big, dark-brown necrotic areas that are usually surrounded by yellow halos. In most severe conditions there occur premature leaf drops. To control the condition you can spray them with a folia fungicide.
  2. Canker. This is another common issue that is mainly identified by a main stem swollen below/near the soil line. The bark soon becomes corky and has many cracks. The stem part that is above the canker is yellow. In case the level of humidity is too high, there may be a yellowish substance seen on the surface. Usually, if the plant is affected, it dies very slowly. To prevent spreading of the disease, it’s better to place other bushes in different locations.
  3. Sooty mold. It leads to appearance of thin black layers of the fungus over the upper surface of the leaves. Leaves curling also accompanies the condition.
  4. Bacterial leaf spot is accompanied by round spots on young leaves; soon they become yellow and reddish-brown, surrounded by a yellow halo. When the infection is severe it leads to defoliation. It is important to avoid overhead watering. To prevent further spreading, make sure you use sterilized pots and soil.
  5. Bud drop. This is an abnormal dropping of buds that takes place during periods of low light intensity or high night temperatures. Of course, in some cases bud drop is a quite normal condition. To avoid the condition, keep the soil moist during flowering, but not wet.

Planting Gardenia from Seeds and Cutting

How to plant a gardenia? The primer rule you should remember is that you should start transplanting either in spring or fall, spacing each plant 3-6 feet apart. To begin with, test the soil in order to determine pH level. In case it is necessary, add the required amount of sulfur, as it’ll reduce the pH level to 5-6. In case the soil is in a rather poor condition, amend the soil you’ve removed from the whole with compost. After placing the seeds, fill the hole ½ full with soil, water it well and eliminate air pockets. Let the liquid drain and fill the remainder of the hole with soil and water.

Propagation through cutting is popular as well. When to transplant? In spring or autumn. Use the cuttings that come from a new growth for the year. They should be neither too woody nor too soft. The best variants are bendable and green stems. The stems should be at least 3 inches long. How to prune them? Cut just below a joint. Lower the end into a root hormone, pull it out and insert into a jar with soil, water the soil and keep it watered for about 6 weeks till the root grows. Transfer it either outside or into a large pot.

Gardenia Bonsai – a Perfect Choice for Your Garden

Gardenia bonsai is a very challenging tree that requires attention and ample care to remain healthy. Extreme temperatures cause the leaves to burn and bloom to follow. This is the primer reason why the plant should better be kept inside in a sunny location, but away from direct sunlight. When winter comes, the tree will manage to survive only if placed indoors.

The surrounding soil should always be moist, but not saturated. This will help to avoid roots rotting. You should monitor the wetness of the soil regularly (esp. during summer months), and water more than once per day if necessary.

Use fertilizer once per month, when it is not in bloom (from late spring till mid fall). The tree thrives if the given fertilizer is designed for acid-loving plants. This will keep the levels of soil at pH of 5.0 to 6.5. Aiming at protecting the plant from insects? Twice a year apply chelated iron powder mixed with water.

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