User avatar
Francis Barnswallow
Green Thumb
Posts: 696
Joined: Fri Sep 03, 2010 7:28 pm
Location: Orlando

What's wrong with my mom's gardenia plant?

This is what it should look like.

Image

We've had this plant for awhile now and still no flowers and it has these spots on the leaves. The flowers that do start to form immediately turn yellow and fall off.

Image

Here's a close up of a spot on leaf.

Image

Any idea what's going on with this plant or what is causing these spots on the leaves?

imafan26
Mod
Posts: 13962
Joined: Tue Jan 01, 2013 8:32 am
Location: Hawaii, zone 12a 587 ft elev.

Some of the leaves look like sun scald. If water stayed on the leaf after the sun came up, it could scorch and leave the brown spots later. Gardenia flowers are not long lasting so if the gardenia fades in a few days it probably does not mean that much.

Gardenias are an understory shrub or tree that likes a rich evenly moist soil. It will wilt if it does not get enough water. It is also a very heavy feeder, likes acidic conditions, and needs to get micronutrients especially iron to avoid chlorosis. It is best to either put the plant under a tree that can give it dappled light or in a spot that gets morning sun in hot summer areas. It can grow in full sun once it is acclimated. Try not to get the leaves wet in the late morning. Either water early in the day so the leaves can dry before the sun gets really hot or later in the evening but try to avoid hitting the leaves in the evening. I give my Aimee Yoshioka which sounds alot like your First Love, slow release fertilizer osmocote every three months and supplement with miracle grow for acid loving plants. Flower bloom, spring and early summer. They need to be deadheaded, as they do not always fall off cleanly. Mulch under plants to preserve moisture and they also need very good drainage. When in season they will produce a profusion of fragrant blooms for many weeks.

https://www.ctahr.hawaii.edu/oc/freepubs/pdf/of-32.pdf

User avatar
applestar
Mod
Posts: 30514
Joined: Thu May 01, 2008 7:21 pm
Location: Zone 6, NJ (3/M)4/E ~ 10/M(11/B)

Can you use the flowers for the yellow food dye or is that only certain cultivar or species?

imafan26
Mod
Posts: 13962
Joined: Tue Jan 01, 2013 8:32 am
Location: Hawaii, zone 12a 587 ft elev.

I've never tried to use gardenia for dye.

Turmeric can be used to dye cloth and food. It is what makes curry yellow and can also be added to rice dishes and will turn rice yellow. It will also stain your fingers, cutting board and counter if you are not careful.

Annato is another plant that colors food. It is also called the lipstick plant. It was actually used during the war as a lipstick substitute. The seed is red but the annato oil can be anything from yellow to yellow orange

Gardenia is not edible, but I looked it up, the seed pods are used to dye cloth yellow. The only gardenia I know of that makes large pods is the tree gardenia.

I have a native gardenia nau. I topped it at 5 ft it was heading toward twenty and it is only a few years old.
It does produce pods with yellow pulp. I have not seen Aimee Yoshioka, gardenia radicans, or veitchii produce pods.
https://nativeplants.hawaii.edu/plant/vi ... _brighamii

User avatar
rainbowgardener
Super Green Thumb
Posts: 25279
Joined: Sun Feb 15, 2009 6:04 pm
Location: TN/GA 7b

But what Francis was talking about:

The flowers that do start to form immediately turn yellow and fall off.

doesn't sound like normal blooming and fading, it sounds like bud drop. Right, Francis? The flowers drop before they open up? Bud drop is common in gardenias:

"The most irritating problem encountered with gardenias is "bud drop,"when flower buds abort just before blooming. Common causes include low humidity, over-watering, under-watering, insufficient light high temperatures, rapid temperature fluctuations, cold drafts or change in plant locations. In other words, gardenias are temperamental!

Bud drop, the abnormal dropping of buds, occurs during periods of high night temperatures or during periods of low light intensity. Some bud drop is a natural condition. Every effort should be made to keep the soil uniformly moist, but not wet, during flowering."
https://www.uri.edu/ce/factsheets/sheets/gardenia.html

That same article mentions several fungal leaf spot diseases of gardenias including this one:

Rhizoctonia Leaf Spot (fungus--Rhizoctonia spp.)
Leaves infected with this fungal leaf spot disease have tan to brown spots up to 1/4 inch in diameter. Spots are circular and zoned. The disease begins on the older leaves and spreads upward when the plants are watered excessively or when air circulates poorly because of overcrowding. Diseased leaves should be destroyed and sterilized soil should be used. Disease-free plants should be used for propagation. Avoid wetting foliage when watering.

Your bottom picture the spot clearly looks "zoned."

I would treat it like a fungal infection.

imafan26
Mod
Posts: 13962
Joined: Tue Jan 01, 2013 8:32 am
Location: Hawaii, zone 12a 587 ft elev.

The spots do look zoned and could be fungal infection as well. Necrotic areas left after they have been sunburned can be infected with fungal disease.

Gardenia here rarely get fungal infections. Glossy green leaves help with that. Even powdery mildew is not that common if the plant has good air circulation. They do have a lot of pest problems aphids on the leaves will encourage black sooty mold. Premature bud drop here is usually caused by the western flower thrips and very hot weather. If the plant is healthy enough and gets enough water, even with the thrips the flowers will open but the edges will brown quickly.



Return to “Flower Gardening & Garden Design”