Known for their intoxicating fragrance, beautiful blooms, and glossy, bright-green, evergreen foliage, gardenia plants dot the landscape across the Southern US.
These heat-loving shrubs thrive when given the right growing conditions: tolerable winters, partial shade, and well-drained, acidic soil that contains plenty of organic matter.
Gardenias are known to be finicky plants though, and they require a considerable amount of maintenance if these growing conditions aren’t perfect.
This includes choosing the right plant food.
For that reason, I have put together this post in which we will talk about what to consider when shopping for a good fertilizer and I will also list a few of my favorites.
Table of Contents
What is the best fertilizer for gardenias?
The quick answer is that Gardenias are acid-loving plants. For that reason, when shopping for fertilizer it is important to use some that contain ammonium-based nitrogen sources. This will continue to feed the plant, but at the same time, it will not affect the overall pH level of the soil.
Here is a quick preview of our top 4 picks. Please continue reading for more information on each one.
- Jobe’s Fertilizer Spikes
- Miracle-Gro Plant Food
- Ferti-Lome Acid Loving Water Soluble Plant Food
- Jobe’s Organics Holly
Choosing the right fertilizer for your plant
As with most other plants, a key aspect in successfully growing gardenias is proper fertilization.
Certain nutrients are classified as essential for all plant growth: nitrogen, phosphorus, potassium, calcium, sulfur, magnesium, sodium, boron, chlorine, manganese, iron, zinc, copper, molybdenum and nickel.
These fifteen nutrients aid in all of the basic, yet critical, functions that occur within the plant.
Without these essential nutrients, plants cannot thrive and will begin to exhibit negative deficiency symptoms. If the deficiencies are left untreated, the plant will succumb to the shortcoming and perish.
Since plants are constantly feeding on the essential nutrients found in the soil they can deplete even the most fertile substrates over time, making it necessary for the homeowner to add plant “food” to grow strong, healthy plants.
Fertilizers add these nutrients to the soil and are classified based on the three main elements that are needed in much higher amounts than the other essential nutrients – nitrogen, phosphorus, and potassium.
Nitrogen is listed first on the fertilizer label since it is considered the most key nutrient needed for plant growth. Its main responsibility in the plant is regulating vegetative growth.
Nitrogen is assimilated in the plant into amino acids, the building blocks of protein; it is also a major component of chlorophyll and helps to keep foliage green, and nitrogen is necessary for many of the plant’s enzymatic reactions.
Phosphorus is a structural component in DNA and RNA (the genetic building blocks within plant cells) and is needed for root growth and flowering.
Potassium works more indirectly in plants than nitrogen and phosphorus. While it isn’t a component of any plant parts, it functions by activating the enzymatic reactions that occur, making it imperative for the overall health of the plant.
Gardenias have special needs compared to other flowering ornamentals and prefer to be fed with a fertilizer made specifically for acid-loving plants. If a fertilizer uses nitrates as its primary nitrogen source, applying it to the soil will gradually increase the soil pH over time.
To keep the soil pH in the appropriate acidic range for gardenias it’s important to use a fertilizer formulated with ammonium-based nitrogen sources. As these fertilizers break down the nutrients released will not affect the soil pH or will slowly continue to acidify it.
Fertilizer for acid loving plants comes in many varieties, allowing the homeowner to choose products that fit their management practices and lifestyle choices.
However, with that being said, here are my top 4 picks.
- Spike Application
- Slow release
- Only one application needed per season
Do Jobe’s Fertilizer Spikes have what it takes to be considered the best fertilizer for gardenias? We say yes, and we think you will agree.
Jobe’s fertilizer spikes are pre-measured to provide nutrients directly to the root zone of acid-loving plants.
Nutrients are slowly released exactly where they need to be and can’t be washed away by rain or irrigation, minimizing the chance of over-fertilization or nutrient runoff.
Application Tips: Insert the easy to use spikes into the soil around the perimeter of the plant to deliver nutrients right to the root zone. It is specifically designed to break down gradually over time and will feed your gardenias all season long with a single application.
- Slow Release
- Helps to keep low pH levels in the soil
- Apply every 2 weeks
Another great plant food for these acid lovers is Miracle-Gro’s Plant Food.
Miracle-Gro products are tried and true, known to be industry leaders for their proven results. Specially designed for acid-loving plants, this plant food is no exceptions.
In addition, it is rich in iron and other essential nutrients for keeping your flowers looking beautiful all season long.
It is formulated with nutrient sources to keep soil pH at a lower, acidic level instead of slowly raising the pH as some fertilizers can do.
Application Tips: Apply the product every two weeks per the label recommendations for lush, green foliage and plentiful blooms.
- Easy to use
- Water Soluble
Another option for acid-loving plants is Ferti-Lome Acid Loving Water Soluble.
This highly concentrated water-soluble formula needs to be diluted in water and then applied to plants using a watering can or hose-end sprayer.
What I like most about this option is that it is formulated to maintain a lower soil pH and is perfect if it’s necessary to add fungicides or insecticides to the plant at the same time as fertilizing – just mix the other products into the diluted fertilizer solution and apply simultaneously, reducing application times.
Application Tips: For optimum results, dissolve 1 teaspoon of in 1 gallon of warm water and apply every time the gardenias are watered.
- Certified Organic
- Water Soluble
- Contain Biozome
- Apply every 14-28 days
If you are looking for a more environmentally conscious product, Jobe’s Organics is a great option.
Certified organic, this water-soluble fertilizer is enhanced with Biozome, a combination of healthy bacteria, mycorrhizal fungi, and Archaea.
Biozome helps create optimal soil conditions by improving soil texture, water retention, and penetration – all which promote plant growth.
Application Tips: Dissolve this fertilizer in warm water per the label instructions and feed plants every 14 – 28 days during their active growing season to encourage beautiful, abundant blooms.
This is even truer when they require the soil pH to be acidic for optimum growth. Using one of the above fertilizers for acid-loving plants will help feed provide plants the essential nutrients they need and keep soil pH in the appropriate acidic range for gardenias.
Using these specially formulated products gives finicky gardenia plants the best growing conditions, and in turn, eases the maintenance gardeners need to complete/perform to keep growing conditions well suited for their plants.
When the growing conditions are perfect – tolerable winter temperatures, partial shade, and well-drained, acid soil full of organic matter – the gardener will be rewarded with stunning gardenia plants full of fragrant blossoms.
Please share with us your experience. What have you found to be the best fertilizer for gardenias?