The Best Fertilizer For Gardenias And Other Acid-Loving Plants

Nothing smells quite as lovely as a gardenia in bloom.  But as most gardeners know, they can present a bit of a challenge. Gardenias are a tricky plant to grow since they need very specific growing conditions when it comes to temperature, water, soil, and humidity. 

That’s why it is so important to choose the best fertilizer for gardenias.  Gardenias need very specific nutrients in order to thrive and choosing a fertilizer specifically for gardenias will give you those creamy-white, fragrant flowers you desire. 

But with so many fertilizers out there, which one is the best for gardenias?  Let’s take a look.

Our Top Pick – Espoma Holly-Tone 

Espoma is a well-known brand in the gardening world and Holly Tone has been a favorite among many gardeners due to both its quality performance and affordability.

This 5-3-3 fertilizer is an organic slow-release formula designed specifically for acid-loving plants.  The combination of feather meal, poultry manure, bone meal, alfalfa meal, green sand, potash, magnesia, and elemental sulfur provides vibrant green foliage and prolific blooms. 

This fertilizer is also packed with additional nutrients such as calcium, magnesium, sulfur, and humic acid.  These additional nutrients aid in the production of chlorophyll, an amino acid that serves as a building block for vital plant proteins.  They also aid in nutrient absorption and strong root development.

Espoma recommends applying twice a year, and in addition to gardenias, holly tone serves as an ideal fertilizer for azaleas, camellias, Dogwoods, Evergreens, Hollies, and Rhododendrons.

Pros

• Organic
• Child and pet friendly
• Low odor
• Slow-release

Cons

• Scent may attract dogs

Other Favorite Fertilizers For Acid-Loving Gardenias

Miracle-Gro Miracid

Scotts Miracle-Gro Miracid is a fertilizer that is intended for acid-loving plants like gardenias and azaleas.  The water-soluble formula contains an N-P-K ratio of 30-10-10 as well as additional nutrients such as copper and manganese. It also prides itself on a non-burning formula (when used correctly) that helps promote plant development and bud formation. 

Manganese is a plant micronutrient that assists the plant with photosynthesis and nitrogen absorption, as well as other biological processes.  Copper not only helps the plant absorb nitrogen but also plays an essential role in the prevention of pests and yellowing leaves. 

In addition to your gardenias, this fertilizer can be used on azaleas, camellias, hibiscus, holly, and orchids. 

Pros

• Formulated for acid-loving plants
• Contains extra nutrients 
• Water soluble 

Cons

• Not organic
• Must be mixed carefully
• Not pet friendly

Nelson Acid Loving Plant Food

This fertilizer formula from Nelson is intended for acid-loving plants like azaleas, camellias, and gardenias and contains both organic and man-made nutrients that lower the soil pH and supply iron. 

This mix delivers the boos your plants need initially as well as the benefits of a slow-release formula that are long-lasting.  It helps your gardenia establish strong healthy roots, dark green foliage, and big, beautiful blossoms. 

Nelson’s Acid Loving Plant Food fertilizer should be applied in early spring and then monthly throughout the growing season. When applied properly, this fertilizer will not burn or damage your gardenias.

Pros

• Available in multiple size jars
• Both fast acting and long lasting

Cons

• Not completely organic

Jobe’s Spikes

If you are looking for a fool-proof, easy-to-use fertilizer for your gardenias and other acid-loving plants, look no further than Jobe’s Fertilizer Spikes.  Each spick contains the perfect amount of pre-measured (9-8-7),  slow-release fertilizer that allows a single application to feed your plants for an entire season.  

Since the fertilizer stick is placed in the ground, the fertilizer is guaranteed to go directly to the roots of the plant with no runoff, waste, or mess involved.  Your plants are getting the exact amount of fertilizer they need to thrive. 

Pros

• Easy to apply
• Mess free
• One application per season

Cons

• Can be difficult to drive into compact soil

Dr. Earth Acid Lovers Organic Fertilizer

Dr. Earth’s fertilizers are some of the most popular among organic gardeners and have been dubbed as one of the purest organic fertilizers on the market today. 

Dr. Earth’s Acid Lovers is an organic fertilizer specially formulated for plants that prefer acidic soil.  This 3-4-3 fertilizer contains hand-crafted feed-grade ingredients such as alfalfa meal, fishbone meal, potassium sulfate, fish meal, kelp meal, and kelp flower.

Its TrueBiotic soil microbes, seven strains of beneficial bacteria, and mycorrhizae help to break down organic nutrients so that your gardenias receive optimal nutrient absorption.  Mycorrhizal fungus is a great source of nitrogen and phosphate and boosts stress resistance to drought and heavy metals that can be found in soil.  In addition to its already mentioned superpowers, mycorrhizae also help to strengthen the plant’s defenses against dangerous soil pathogens. 

In addition to gardenias, this formula is ideal for azaleas, camellia, rhododendron, maples, and blueberries. 

Pros

• Organic
• Child and pet-friendly
• TruBiotic technology

Cons

• Its smelly

Yum Yum Mix

Yum Yum Mix is another organic fertilizer that was created by Santa Fe landscape design expert Donna Broner.  Her 2-1-1 fertilizer is especially good for the nutrient-poor alkaline soils found in New Mexico and other areas of the southwest. 

Yum Yum Mix is made from alfalfa meal, dry molasses, cottonseed meal, green saint, humate, kelp meal, and rock phosphate. This fertilizer is great for plants that love acidic soils and is also safe to be used for growing vegetables. 

The impact this fertilizer has on the microorganisms in the soil draws earthworms and other soil microbes as it breaks down minerals and other organic matter. 

It is also vegetarian-friendly as it does not contain any animal products such as blood or bone meal.

Pros

• Organic 
• Child and pet save
• Vegetarian-friendly

Cons

• A bit smell

A Little Bit About Gardenias

These heat-loving creamy-white flowers are native to the tropical regions of Africa, Asia, and Australia.  Best known for the pleasant fragrance of their beautiful white flowers, they are not exactly the easiest shrubs to grow. 

Gardenias thrive in humid, tropical conditions with warmer days and cooler nights. Not only do they need a precise nutrient mix, but they also need moist, well-draining, acidic soil, and bright, indirect light for optimal growth. 

Plant Features And Requirements

One of the main reasons gardenias are so difficult to grow is because of their unpredictable needs which vary from area to area.

Sun Exposure

The sun exposure requirements directly correlate to the climate you are in.  Gardenias prefer a moderate amount of sunlight.  Too little or too much will hinder plant growth.

As a general rule, gardenias should receive morning sun and afternoon shade in warm climates and can tolerate full sun in cool climates but the roots should be insulated with a layer of mulch.  Gardenias grown in containers should receive indirect sunlight and those grown indoors should get 6-8 hours of direct sun. 

Temperature Requirements

Gardenias love humidity and have very strict temperature requirements.  They thrive in areas where daytime temperatures reach 65℉-70℉ and evening temperatures remain just above 59℉.  Temperatures exceeding 70℉ can cause blossoms to quickly drop.

Soil Requirements

Since gardenias are acid-loving plants, the soil they are grown in should be pretty acidic with a pH of 5.0-6.0. The soil should be kept moist but should never be overwatered.  Nutrient-rich soil mixed with peat moss and manure is ideal and the plant should be mulched to maintain a steady soil temperature and lock in moisture. 

Gardenia Varieties

Gardenias have several different varieties that are categorized by the gardenia’s distinct features. 

Large Cultivars

• Aimee
• Belmont
• Fortuniana
• Miami Supreme
• Supreme

Medium Cultivars

• ​​August beauty
• Chuck Hayes
• Coconut Magic
• Daisy
• Frostproof
• Heaven Scent
• Jubilation
• Pinwheel
• Veitch
• Celestial Star

Dwarf Varieties

• Buttons 
• Crown Jewel
• Four Seasons
• Golden Magic
• Kleim’s Hardy
• Radicarn
• ScentAmazing

Hardy Varieties

• Belmont
• Chuck Hayes
• Daisy
• Frostproof
• Heaven Scent
• Jubilation
• Kleim’s Hardy
• Pinwheel
• Celestial Star
• ScentAmazing

Acid-loving Plants

Gardenias, as well as all acid-loving plants like hydrangeas and blueberries, prefer fairly acidic soil with a pH of around 5.5.  Certain fertilizers, such as blood meal, cottonseed meal, and fish emulsion, can help the soil to maintain a low pH.  There are a variety of fertilizers available geared specifically toward acid-loving plants such as azaleas, rhododendrons, blueberries, heathers, and of course, gardenias. 

Signs Your Gardenia Plant May Need Fertilizer

Since gardenias can be so finicky when it comes to care, it is often difficult to tell if the problem is a lack of fertilizer or one of many other issues.  The best way to know for sure is to have the soil tested at least once a year. 

There are, however, other signs that may indicate your gardenia plant is lacking nutrients.  The lack of nutrients can be caused by many things. 

Insects, especially larvae from the black vine weevil can cause root damage, preventing the plant from absorbing the nutrients it needs to thrive.  Excess sodium in the soil can also be an issue. There are a few signs you may notice that indicated fertilizer application may be necessary.

Yellow Leaves

When leaves do not get enough nitrogen, the green leaves begin to turn yellow.  Not only are yellow leaves unattractive, but they also reduce the amount of photosynthesis the plant is able to perform, limiting the amount of food the plant receives. If the yellow leaves are curled with green veins, your gardenia most likely has an iron deficiency. 

Stunted New Growth

All plants need nitrogen to grow and a lack of it will inhibit new growth.  

No Flowers or Flower Buds

When nutrients are lacking, the plant goes into survival mode. In order to fulfill its essential needs, the gardenia gets rid of anything unnecessary.  This means it drops its blossoms and focuses on root growth to absorb essential nutrients. 

Fertilizing Gardenias – Types Of Fertilizers And How To Use Them

How to fertilize your gardenia plant largely depends on the type of fertilizer you choose. A good rule of thumb is to stick to the manufacturer’s instructions, but we have also listed a few other application tips.

Liquid Fertilizer

Liquid fertilizer should ALWAYS be mixed according to the package instructions.  Using a fertilizer that is mixed too strong will result in further damage to the plant and even total loss.  That said, if you want to err on the side of caution, we recommend starting by mixing your fertilizer to half-strength. This will ensure that you do not over-fertilize the plant. Using a pH soil test will let you know where you are starting and give you a better idea of how much fertilizer is needed.

Liquid fertilizer can be applied in several ways.  If you need to cover a large area, a sprayer is a good idea, but if you are only fertilizing a small area or potted plants, a watering can will get the job done. 

When fertilizing, keep in mind that some fertilizers are meant to be applied only to the roots while others should be applied to the roots AND foliage.  Read package instructions carefully to make sure you are fertilizing correctly.   

Fertilizer Spikes

Spikes are one of the easiest fertilizers to apply.  Simply insert the spick into the soil and make sure you water the gardenia properly.  Since most fertilizer spikes contain slow-release fertilizers, they are one-and-done, meaning you don’t have to reapply them often. 

Fertilizer Granules

Granules, like spikes, are designed to be slow-release.  The coating on each granular breaks down over time, slowly allowing small amounts of nutrients to seep into the soil.  As with liquid fertilizers, application varies depending on the specific product you are using.

Application also varies depending on the type of plant. If you are using a granular fertilizer on a new plant, it is generally ideal to mix the granules into the soil  and water it in generously before planting. If fertilizing an established gardenia, scatter the granules around the base of the plant, as well as its waterline, then water.  Always apply the granules dry first, and then water them in. 

Natural Fertilizers

If you are an organic gardener and want to stick to natural fertilization methods, there are a few products you should keep on hand. Cottonseed meal, fish emulsion, blood meal, white vinegar and compost tea are some of the best natural fertilizers for gardenias as well as other acid-loving plants. 

Also, amending the soil with compost, aged manure, coffee grounds, tea bags, wood ash, and epsom salt will help provide essential nutrients and allow your gardenias to thrive. 

Other Tips

• ONLY fertilizer from March to October and NEVER fertilize gardenias from November to February
• Apply fertilizer every 2 to 4 weeks
• Stick to fertilizers for acid-loving plants
• It is better to err on the side of caution because overfertilizing can lead to blossom drop

N-P-K Ratio

The fertilizer’s N-P-K ratio is the numerical value of the parts of Nitrogen, Phosphorus, and Potassium.  

Since gardenias love soil with a pH of 5 to 6, you need to be sure that the ratio of Nitrogen, Phosphorus, and Potassium maintain that pH.  Gardenias grow best when fed fertilizer that contains an N-P-K ratio of 3-1-2 or 3-1-3.

Each bag of fertilizer should have the N-P-K ratio listed on the label so you can make sure you have the best acidic fertilizer for gardenias.

Calculating The Amount Of Fertilizer Needed

Gardenias generally need around 1 pound of nitrogen per 1,000 square feet of garden, or 0.1 pound per 100 square feet.  Since different fertilizers contain different amounts of nitrogen, you can calculate how much to use by dividing the percentage of nitrogen in the fertilizer by 100. 

If you fertilizer contains 8% nitrogen (100➗8=12.5)  you will need to use 12.5 pounds of fertilizer per 1,000 square feet of garden. If you only need to fertilize 100 square feet, divide that number by ten (12.5➗10=1.25).  For 100 square feet, you would need to spread 1.25 pounds of fertilizer. 

Container Grown Gardenias

Fertilizing gardenias grown in pots and other containers is a whole different ball game and you will need to be very careful to avoid damaging the plant.  Luckily, most garden centers and nurseries carry fertilizers that are specifically formulated for container-grown plants. Be sure to choose a fertilizer formulated for acid-loving plants, and as with all fertilizers, follow the directions exactly to avoid damaging or even killing your gardenia.

Pest Control

Common pests that can be found on your gardenias are spider mites, whiteflies, and mealybugs.  You can keep your gardenias from these unwanted culprits by keeping the humidity high and using a high quality horticultural oil, or insecticidal soap as needed. 

FAQ

Is 10-10-10 fertilizer good for gardenias?

As mentioned earlier, a 3-1-2 or 3-1-3 ratio is best.

How often should gardenias be fertilized?

Gardenias should be fertilized every 2 to 4 weeks, but we recommend starting with every 4 weeks to avoid over fertilization.

Do gardenias like coffee grounds?

Yes!  All acid-loving plants love coffee grounds. Thoroughly mix them into the soil, and the nitrogen they release will make your gardenias quite happy!

Is Miracle-gro good for gardenias?

It depends, there are a variety of types of Miracle-gro plant food.  We suggest using one intended for acid-loving plants like Miracid

How do I fix yellow leaves on my gardenia plant?

Yellow leaves can be a sign of lack of nutrients or root damage.  Test your soil first and fertilize as needed. 

Bottom Line

When it comes to the best fertilizer for gardenias, a 3-1-2 or 3-1-3 ratio is best and you should always use a “less is more” approach to fertilization.  You can always add fertilizer if needed but once you have added too much, the damage is done.