A genus of flowering plants from the Rubiaceae (coffee) family, Gardenia species are highly praised for their exquisite creamy-white, fragrant flowers and attractive dark-green foliage.
While they are not easy to grow and known as finicky plants with particular growing requirements and high susceptibility to diseases, their beautiful flowers and glossy foliage make up for the extra attention they need.
Whether cultivated in the ground or a pot, gardenias need the right care and regular maintenance to flourish.
And this includes feeding the plants with the right kind of fertilizer at the right times.
Fertilizing is essential for gardenias to ensure healthy growth and vigorous flowering.
Best Fertilizer for Gardenia Care
The members of this genus including the ground cover Gardenia varieties are acid-loving plants. Hence, they will not benefit from an all-purpose fertilizer.
While you are allowed to use liquid, pellet, or powder fertilizer, make sure it has higher acidic content.
Use the ones specifically meant for acid-loving plants (Azaleas, Camellia, Rhododendron) or supplement with materials, like Epsom salt, tea, or coffee grounds to make it a more acidic soil pH.
Fertilizers containing additional copper or iron also promote the development of leaves and flowers.
Here are some popular and widely used commercial fertilizers for gardenia plants you’ll find at the garden center:
- Scotts Miracle Grow MirAcid
- Fox farm Grow Big
- Cottonseed meal
When or How to Fertilize Gardenias
As discussed above, fertilization is one of the most important elements of caring for gardenia plants.
While fertilization is essential to maintain a consistent supply of nutrients essential for healthy growth and blooming, too much fertilization will burn the plants.
To prevent over-fertilizing, experts recommend to only feed the plant once a month through the growing season – early spring, early summer, and late summer.
Do not fertilize gardenias in fall and winter, when they are dormant (you may fertilize in early fall when they are not dormant).
Another tip to avoid over-fertilizing is to use lesser amount than what is recommended on the packaging.
Depending on the type of fertilizer you are using, apply it diluted in water (liquid fertilizer) or mix directly into the soil (powder or granular fertilizer).
Mix one tablespoon of white vinegar in a gallon of water and water gardenia plants with it once a month helps to maintain the acidic soil pH.
Important: Always water the plant, only lightly though, before fertilizing.
Applying gardenia fertilizer when the soil is completely dry may damage the roots.
Related: Learn Tips about Gardenia Soil | Lowering Soil pH with Vinegar
Signs of Lack of Fertilizer
In an attempt to prevent over-fertilizing, sometimes people end up under fertilizing the gardenia plants, which affects the plant in many ways.
If your gardenia jasminoides are exhibiting any of the following signs, it means you are not fertilizing them enough:
Stunted New Growth
A lack of nitrogen inhibits new growth.
If any of this evergreen shrub isn’t producing new growth, it is a sign of lack of this essential nutrient due to under-fertilizing.
The plant grows best in USDA hardy zones 8 – 11.
These house plants are vulnerable to pests such as aphids, mealybugs, whiteflies, and mites when grown indoors, so they should be monitored daily, watch out for sooty mold, and infestations treated immediately.
Use a horticultural oil or insecticidal soap to control these pests.
Yellow Leaves
Leaf development, again, is highly dependent on the amount of nitrogen gardenia plants are getting from the soil.
When they do not get an adequate amount of nitrogen, then the green leaves start to turn yellow.
More on Yellowing Leaves on Gardenia Plants
And the lack of healthy leaves means the plant’s ability to perform photosynthesis will be reduced, as a result of which they won’t be able to make enough food.
Yellow, curled leaves with green veins is a sign of iron deficiency.
Prune away dead areas.
All these factors contribute to poor health and reduced growth and blooming.
Absence of Flower Buds or Flowers
The lack of nutrients in the soil makes the plants go into survival mode, during which it only uses, whatever nutrients are available, to fulfill its essential survival needs, such as the development of roots and causes bud drops.
To sum up, the lack of essential nutrients and organic matter significantly affects the health and growth of gardenia plants.
Use mulch, peat moss, and avoid extended periods of full sun to keep it healthy.
Feeding with the right fertilizers will help encourage foliage and flower development, once again, by restoring the nutrient balance of the soil.