Gardenia
Sources last read 14 September 2026.
Difficult One of the harder ones, and one of the reasons the diagnosis tool exists.
Also called Cape Jasmine, Cape Jasmine Gardenia, Cape jessamine, common gardenia and jasmin.
Gardenia is toxic
- Toxic to cats. Toxic principle: Genioposide, Gardenoside. Clinical signs: Mild vomiting and/or diarrhea, hives. ASPCA
- Toxic to dogs. Toxic principle: Genioposide, Gardenoside. Clinical signs: Mild vomiting and/or diarrhea, hives. ASPCA
- Not assessed for people. RHS publishes no harm statement for this plant. That is not a finding of safety: none of the sources read for this site gives an answer either way. Treat it as unknown.
What the sources say about its care
- Light
- Partial shadeRHS · read 13 September 2026
- Water
- Moist but well-drainedRHS · read 13 September 2026
- Humidity
No source read publishes a humidity figure for any plant on this site. What follows is general guidance for foliage plants.
ASHRAE recommends indoor relative humidity between 30% and 60% 30–60%Penn State Extension · read 13 September 2026- Temperature
How cold this tolerates, not what it prefers. No source read for this site publishes a preferred range for a plant indoors.
H1C — 5–10°C 5–10 °CRHS · read 13 September 2026- Soil
- Clay, Loam, Sand; pH Acid or NeutralRHS · read 13 September 2026
- Toxic to cats
- ToxicASPCA · read 13 September 2026
- Toxic to dogs
- ToxicASPCA · read 13 September 2026
- Harmful to people
- No statement of harm to people is published for this plant; that absence is not evidence it is safe.RHS · read 13 September 2026
How it usually goes wrong
- Buds form and fall before they open
Buds on the gardenia stop swelling, turn pale at the base and fall, usually a few at a time over a week or two.
Sudden changes in light, warmth or watering cause buds to be abandoned, because a bud is expensive and the plant cannot tell whether conditions will recover. Its source describes partial shade.
Telling it apart: When the buds dropped. Within days of a move or a dry spell is the change; buds that drop with nothing changed point at uneven watering or pests on the buds.
RHSDiagnose leaf drop on this Gardenia- Crisp margins that appear in winter
The gardenia shows browning on many leaves at once, all at the margin, with no spots or soft patches anywhere.
Leaf margins are the end of the water supply, so they are the first tissue to run short when the air takes more than the roots can send. Penn State Extension cites 30% to 60% as the recommended indoor range, and a heated room in winter sits below it.
Telling it apart: Whether it crumbles or smears. Crisp is water lost; soft and dark is cold or rot.
Penn State ExtensionDiagnose brown tips and edges on this Gardenia- Growth slows and what does arrive is thin
Nothing browns and nothing drops; the gardenia simply makes less, and what it makes is stretched and thin.
A plant stretches when the light is short of what it evolved for. Its source describes partial shade, and a room darker than that sets the plant reaching.
Telling it apart: What the newest growth looks like beside the oldest. Light changes what arrives next; feeding changes what is already on the plant.
RHSDiagnose leggy growth on this Gardenia- Yellow, limp leaves at the base
The lowest leaves of the gardenia go yellow and translucent at the stalk and drop with a light pull, while the compost stays wet.
Soil described as moist but well-drained is a drainage instruction as much as a watering one. Compost that stays saturated suffocates the fine roots that do the drinking.
Telling it apart: The soil, not the leaf. Wet compost under yellowing leaves points one way and dry compost the other, and the leaves alone will not tell you which.
RHSDiagnose yellowing leaves on this Gardenia
Not sure which it is? Ask the diagnosis questions for Gardenia.
Routine care
- Feeding
- Avoid feeding in fall, because it triggers a flush of growth that frost can damage.NC State Extension · read 13 September 2026
- Propagation
- Gardenias can be increased from seed, stem cuttings, layering or grafting.NC State Extension · read 13 September 2026Increase from seed or from greenwood or semi-hardwood cuttings.RHS · read 13 September 2026
- Pruning
- Prune gardenias in spring to keep their shape; flowers form on new growth.NC State Extension · read 13 September 2026
- Pests and diseases
- Can be troubled by gardenia pests, including citrus whitefly, aphids, thrips, whiteflies, barnacle scale and banded greenhouse thrips.NC State Extension · read 13 September 2026Under glass, mealybugs and glasshouse whitefly can occur. Diseases: glasshouse grey moulds can occur.RHS · read 13 September 2026
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Photographs
About the plant
Gardenia jasminoides, commonly known as gardenia and cape jasmine, is an evergreen flowering plant in the coffee family Rubiaceae. It is native to the subtropical and northern tropical parts of the Far East. Wild plants range from 30 centimetres to 3 metres in height. They have a rounded habit with very dense branches with opposite leaves that are lanceolate-oblong, leathery or gathered in groups on the same node and by a dark green, shiny and slightly waxy surface and prominent veins.
From Wikipedia, CC BY-SA 4.0 · read 13 September 2026
- Native range
- E. Himalaya to C. & S. China and Indo-China, SC. & S. JapanWorld Checklist of Vascular Plants, June 2026 release, CC BY.Kew WCVP · read 13 September 2026Southern China, Taiwan. Japan, and VietnamNC State Extension · read 13 September 2026China, JapanRHS · read 13 September 2026
- Climate
- subtropicalWorld Checklist of Vascular Plants, June 2026 release, CC BY.Kew WCVP · read 13 September 2026
- Growth form
- Perennial, Shrub; habit dense, mounding, multi-stemmed, roundedNC State Extension · read 13 September 2026Bushy (evergreen)RHS · read 13 September 2026
- Size
- Height 48–96 in; width 48–96 inNC State Extension · read 13 September 2026Height 1-1.5 metres; spread 1-1.5 metres after 5–10 yearsRHS · read 13 September 2026
- Flowering
- Flowers cream/tan, gold/yellow, white; blooms in spring, summerNC State Extension · read 13 September 2026Flowers white in summer and autumnRHS · read 13 September 2026
- Uses
What sources record people using this plant for. A traditional or medicinal use listed here is a record of use, not advice to eat it or treat anything with it.
The fruit yields a yellow dye for coloring food and clothing, and Chinese herbal medicine uses it too.NC State Extension · read 13 September 2026
Common problems with Gardenia
More of the Rubiaceae family
Plants with similar care
Barberton daisyEdges of the leaves brown while the middle stays sound
Dendrobium orchidA thin dry rim that crumbles between the fingers
Florist's cyclamenBuds that yellow and drop on a leafy plant
Indian azaleaDry, bruised edges after a cold, windy spell
- No photograph yetZebra plantBrown, papery patches on the leaves nearest the glass
Sources
- ASPCA · read 13 September 2026
- Kew WCVP · read 13 September 2026
- NC State Extension · read 13 September 2026
- Penn State Extension · read 13 September 2026
- RHS · read 13 September 2026
- Wikipedia · read 13 September 2026
What this does not cover
The figures above are what published sources say, not measurements of the plant in your room. They say nothing about your pot size, your water, the season, or how far from the glass the plant stands, and those decide more than any figure here does.
Humidity has no species figure because no source read for this site publishes one, and the only temperature published for this plant is a cold floor. The simulator fills those gaps with general figures for its kind of plant, marked as general and listed on how we read sources. Where a toxicity row says the plant was not assessed, that is the absence of a finding and not a finding of safety.
If something is already wrong, the diagnosis tool asks about the soil, the window and the watering, which is where the answer usually is.