Gardenias can be a tricky plant to grow in part because they’re pretty picky. This plant likes everything to be just right – temperature, humidity, water, and soil.
That’s why it’s so important to use the best fertilizer for gardenias. It really helps get the most out of this beautiful plant.
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What is the Best Fertilizer for Gardenias?
As we mentioned, taking care of gardenias is a lot of work but, with the help of the right fertilizer, this can quickly become one of the most beautiful plants in your garden. Fertilizing them provides all the nutrients they need and makes sure the soil is the right pH to help with absorption.
Gardenias are acid-loving plants, they need moist, well-drained, acidic soil (pH 5.5) for optimal growth. While you can control the moisture of the soil easily enough, getting the pH right can be tricky. That’s why it’s so important that any fertilizer you use on a gardenia is formulated to lower the pH.
Look for fertilizers with organic ingredients as, most of the time, these will naturally lower the pH of the soil. Another ingredient to look out for is aluminum sulfate which also gets the job done.
If you’re looking for fertilizer to help with leaf and flower development as well as lowering soil pH, use one that also includes iron or copper to encourage healthy, robust growth.
The Best Fertilizers For Gardenia Plants Growth & Blooms
There are some great products on the market when it comes to the best fertilizers for gardenias. Whether you’re looking for liquid, spikes, or granules, we found ten of the best options out there.
Gardenia Fertilizer Reviewed
1. Miracle-Gro 1000701 Plant Food
Miracle-Gro is a pretty well-known brand when it comes to fertilizer and this plant food is perfect for gardenias as well as azaleas, hydrangeas, orchids, and many more. What makes it so effective is it feeds right at the root for fast results.
This food comes in powder form. It’s mixed with water then applied using a sprayer or watering can. Soak the base of the plant to make sure the fertilizer makes its way down into the soil to the roots. The manufacturer recommends feeding every one to two weeks.
When used as directed, this fertilizer won’t burn or hard your plants. It’s rich in iron and nutrients gardenias need to grow lush leaves and bright blooms. For best results, follow mixing instructions carefully, using roughly one tablespoon for every gallon of water.
2. Espoma HT36 Holly-Tone Plant Food
Espoma’s Holly-Tone plant food is a great choice for gardenias as well as dogwoods, camellias, evergreens, and more. It works with new or established plants and is safe for organic gardening as it’s made using organic materials enhanced with bio-tone.
Holly-Tone comes in granules and is meant to be watered into the soil, dissolving slowly over time. Espoma recommends applying this product to acid-loving plants like the gardenia twice a year – one in the spring and again in the fall, using half of the recommended amount in the fall.
This fertilizer comes in a 36-pound bag and is available in packs of two, three, or four if you prefer to order in bulk. The bags are resealable, too, so you don’t have to worry about spilling and they’re easy to store.
3. Jobe’s Fertilizer Spikes
One of the best things about Jobe’s Fertilizer Spikes is that they’re so easy to use. Each spike is pre-measured with the right amount of fertilizer and the time-release formula means you’re covered for a longer period of time. A single application feeds your plants for a whole season.
Another great thing about spikes is that the fertilizer is guaranteed to get right down to the roots. There’s no runoff, waste, mess, or smell and you can rest assured that your plants are getting the nutrients they need to thrive.
One pack contains ten spikes in a waterproof, resealable pouch. You can order in bulk if you need two, three, or four packs to cover your gardenias. For best results, Jobe’s recommends placing these spikes in late spring or early summer, after plants have shed their blooms.
4. JR Peters Jacks Classic No.1.5 Acid Special Fertilizer
This acid special fertilizer from JR Peter’s is a great choice for gardenias in your garden or grown indoors. It feeds through the leaves and roots to keep the whole plant strong and healthy. It works by lowering the pH in the soil to make iron and other nutrients more available to the plant.
There are detailed mixing instructions on the side of the container. Outdoor plants should be fertilizer generously about every two weeks while houseplants do better when they get a little bit of fertilizer with every watering.
One of the nice things about this product is it comes in a large, one-gallon plastic tub. It’s resealable and watertight to keep the fertilizer fresh. Since you only need to use between ¼ and one tablespoon with every application, a single tub could last a really long time. That said, two, three, four, and five packs are also available to buy in bulk.
5. Dr. Earth 703P Organic Acid Fertilizer
If you’re looking for an organic fertilizer for your gardenias, take a look at this one from Dr. Earth. It contains probiotics, seven strains of beneficial bacteria, and mycorrhizae. Everything is 100% natural and a single application feeds your gardenias for months.
These ingredients not only increase the acidity of the soil but it also protects against drought. The probiotics break down the nutrients and release them into the soil, making it easy for your plants to absorb. It works quickly and continuously for long-lasting results.
Since this product is organic, it’s safe for people and pets when used effectively. It comes in a four-pound resealable bag and can be purchased in two, three, or four-packs. One bag feeds about 16 five-gallon plants. Detailed mixing instructions are on the bag.
6. Nelson Plant Food for all Acid Loving Plants
Nelson Plant Food is a great choice for gardenias. This formula for acid-loving plants contains four different ingredients to lower pH as well as multiple sources of nitrogen and iron as well as cottonseed to make sure plants get the nutrients they need over an extended period of time.
This mix delivers a strong boost for your plants followed by long-lasting benefits. It helps plants establish deep, lush green leaves and grow strong, healthy roots while increasing tolerance to drought and encouraging the growth of big, beautiful blooms.
With proper application, this fertilizer won’t burn or damage your plants. For best results, the company recommends applying at the beginning of spring and again monthly throughout the growing season. These granules are available in two, four, 15, and 25-pound resealable jars.
7. Scotts Company Miracle-Gro 1750011 Acid-Loving Plant Food
Miracle-Gro’s Miracaid plant food is great for gardenias as well as other plants that love acidic soil, like azaleas, rhododendrons, and hydrangeas. A one-pound container covers about 400 square feet and six-packs are available if you prefer to buy in bulk.
One of the best things about this fertilizer is its double-feeding action. That means plants get nourishment through both the roots and the leaves, promoting strong blooms and roots and lush green leaves.
You can mix and apply this product using either a sprayer or a simple watering can. The brand recommends using it to feed your plants every seven to 14 days during the growing season. Use the easy-to-follow mixing instructions on the side of the package for the best results.
8. Sunniland Azalea, Camellia and Gardenia Fertilizer
The fertilizer from Sunniland is specially made for gardenias, camellias, and azaleas but can also be used for dogwood, hibiscus, and any other acid-loving plant. It’s appropriate for indoor and outdoor use, too.
The iron and manganese in this plant food make for bigger, brighter blooms, strong roots, and lush greenery. Sunniland recommends applying this product in the early spring after the bloom is over and again in August to replenish the soil after the summer growing season.
This product comes in granular form and is formulated for continuous release. Granules should be spread around the base of the plant and watered into the soil. If you have a lot of plants to tend to, this product is a great choice. It comes in a large 20-pound bag that should last a while.
9. Lilly Miller Rhododendron Evergreen and Azalea Food
A great choice when it comes to gardenia fertilizer is this product from Lilly Miller. It’s a good fit for all acid-loving plants, including rhododendrons and evergreens. Make sure to follow the instructions carefully as application varies from plant to plant.
This fertilizer contains natural ingredients, including cottonseed meal to make sure the benefits are spread out over time. It also includes four sources of nitrogen as well as a mix of plant food and nutrients. This combination helps to quickly improve the quality of the soil to benefit your plants.
You can get this product in a four or sixteen-pound bag depending on how much you need to get the job done. When used properly, one application lasts up to six weeks so you don’t need to worry about applying it too often.
10. Bonide Products INC 705 037321007050 Aluminum Sulfate
This is one of the simplest fertilizers available for gardenias. Why? Because it’s made of 100% aluminum sulfate. It lowers the pH of the soil, increasing its acidity and allowing plants like gardenias, azaleas, and more to get the nutrients they need.
Something special about this product is it works in just about any type of soil. So, whether you’re using a special blend for potted plants or have a gorgeous gardenia bush in your front yard, this product can help.
The package includes an easy-to-follow chart that tells you exactly how much to apply depending on the soil pH. The company recommends having your soil tested first to get an accurate pH level. Then, use the included chart to determine how much product to add to lower the pH to 5.0, the ideal acidity for acid-loving plants.
Feeding the Acid Loving Gardenia Plant
By now, you know that gardenia plants are picky – but don’t let that discourage you. With a little time, attention, and the right fertilizer, you’ll have a beautiful plant in no time.
When to Fertilize Gardenias?
When to fertilize depends on a few things.
If you’re planting a new gardenia plant, it’s a good idea to have the soil tested before you do anything else. That way, if you do need to correct the pH, you can do so before planting so your gardenia starts out with the best possible soil.
Generally, gardenias should be fertilized three times a year – in the spring, summer, and fall. Gardenias are an evergreen plant which means they will continue to grow all year in the right conditions. That said, you should still give them a break during the winter months.
Some people skilled at raising gardenia recommend checking soil pH monthly to check if intervention is needed. It should be between 4.5 and 5.5. As we’ve mentioned a few times, this is a picky plant that can be a lot of work so staying ahead of any pH changes is a good idea.
If you check the soil pH a few weeks after you’ve applied fertilizer and it’s not what it should be, another application will be necessary. In most cases, it’s a good idea to follow the manufacturer’s instructions.
A lot of things can affect soil pH which is why it’s important to check it somewhat frequently. Where you live and the type of soil and land around you can have an impact as can the location of the plant itself.
Plants close to walkways, sidewalks, and driveways tend to have soil that is more alkaline because of certain minerals being leached from the concrete. These areas may require more frequent fertilization than other areas of your yard.
The pH of the water you use to water the plant could also have an impact, whether it comes from the tap or a garden hose. Rainwater can also change the acidity of the soil.
As you can see, there’s a lot to think about. The best way to make sure you’re on top of everything is to check soil pH every month and make the appropriate adjustments.
How to Fertilize Gardenias?
How to fertilize your gardenia depends on the type of fertilizer you choose. You should always follow the manufacturer’s instructions but here are some basic things to keep in mind.
Liquid Fertilizer
Liquid fertilizer should be mixed according to the package instructions. That said, some people recommend mixing it to ½ strength just in case full strength is too much for your plant. Again, this is why a pH soil test comes in handy. If you know where you’re starting from, it’s easier to decide how much fertilizer to use.
Some liquid fertilizers are meant to be applied to the leaves and the roots while others should be applied to the root only. Again, follow the instructions on the package to make sure you get it right.
If you’re using liquid fertilizer, you can apply it in various ways. To cover large outdoor areas quickly, use a sprayer. For smaller areas or for potted plants, try a watering can or any large container that allows you to mix the fertilizer well.
Now, if you check the soil pH a few weeks after you’ve applied fertilizer and it’s not what it should be, another application will be necessary. In most cases, it’s a good idea to follow the manufacturer’s instructions.
It varies from one product to the next but most liquid fertilizers should be applied once or twice a month. Check the label to be sure.
Spikes
Spikes are probably the easiest type of fertilizer to apply. All you have to do is insert them into the soil and make sure to water your gardenia properly. Most spikes are designed to slowly release nutrients into the soil so you don’t have to worry about reapplying very often.
Granules
Granules are also designed to be slow-release. They have a coating that slowly breaks down, allowing small amounts of nutrients into the soil at a time.
Again, application varies depending on the product as well as the type of plant you’re using it on. For a new plant, it’s usually a good idea to thoroughly mix the granules into the soil first and water generously.
As for established plants, granules should be scattered around the waterline and the base of the plant and watered in. Granules should always be applied to the soil and then watered. They are not meant to be mixed with water and then applied to the plant.
Signs of Lack of Fertilizer for Gardenias
With gardenias, it’s not always easy to tell if the problem is a lack of fertilizer is the problem because their care requirements are so particular. The best way to know for sure if the fertilizer and soil are the problems is to have the soil tested regularly.
That said, there are some things you can look for that indicate there may be a problem with your gardenia. Most problems are caused by a lack of nutrients but this isn’t always because of the fertilizer.
Sometimes, insects can damage the roots of the plant. One particularly damaging one is black-vine weevil larvae. They can tear up the roots, preventing the plant from absorbing necessary nutrients.
Another problem might be that the soil has too much salt in it. This can be caused by too much fertilizer or it may just be that the plant is in a place with naturally salty soil.
Gardenias like moist soil but it’s possible that the soil is too wet. In this case, the leaves may turn yellow and the leaves may droop. If the plant isn’t getting enough water, the leaves will turn brown and may crisp if they are burned.
As you can see, it’s not always easy to determine what is wrong with a gardenia that isn’t thriving. It is entirely possible that the plant isn’t getting enough fertilizer but the only way to know for sure is to get the soil tested.
Conclusion
Gardenias are a beautiful plant that has a reputation for being a little difficult to manage. One of the things you can do to make it a little easier is to make sure you’re using the right fertilizer.
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