Top 5 Best Fertilizers For Oak Trees (2021 Review)

Oak trees are beautiful, hardy trees that can be grown just about anywhere. They’re often ‘street trees’ in cities and urban areas, and they provide a lovely canopy of shade during the hot summer months.

The biggest issue with trees, though, is that they’re slow-growing. Life is short for humans, but not so much for trees!

Fertilizing your oak tree is something you probably haven’t thought about before, but it can make a world of difference, especially for young oaks.

Investing in a high-quality fertilizer for your oak tree can speed up growth and leaf production, giving you relief from the glaring July sun as quickly as possible. It also keeps your oak strong and healthy, helping to prevent damage from storms. You may be skeptical now, but keep reading to learn more about why fertilizing your oak tree is a good idea!

In this guide, you’ll learn:

  • Why you should fertilize your oak tree
  • How to choose the right fertilizer for your oak tree
  • How fertilizer will promote healthy growth and keep your oak tree strong
  • And much more!

Below is a quick list of my favorite fertilizers for oak trees. Keep scrolling to learn more of my top tips to choose and use the best fertilizer for your oak.

ImageProduct
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BioAdvanced 12-Month Insect Killer and Fertilizer
  • Insect repellent
  • Slow-releasing
  • Built-in measuring cup
  • Insect repellent
  • Slow-releasing
  • Built-in measuring cup
View on Amazon
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Humboldts Secret Tree Trunk
  • Strengthens tree trunks
  • Quick results
  • Liquid form
  • Strengthens tree trunks
  • Quick results
  • Liquid form
View on Amazon
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Jobe's Tree Fertilizer Spikes
  • Easy to use
  • Feeds at the roots
  • Strong nitrogen content
  • Easy to use
  • Feeds at the roots
  • Strong nitrogen content
View on Amazon
digital-business-prep-table__image
Scott's Evergreen Flowering Tree & Shrub Continuous Release Plant Food
  • High nitrogen content
  • Promotes strong roots
  • Budget-friendly
  • High nitrogen content
  • Promotes strong roots
  • Budget-friendly
View on Amazon
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Miracle-Gro Tree & Shrub Plant Food Spikes
  • Trusted brand
  • Easy to use
  • Slow-releasing
  • Trusted brand
  • Easy to use
  • Slow-releasing
View on Amazon

My Overall Top #1 Pick: BioAdvanced 12-Month Insect Killer and Fertilizer

Even though all of these oak tree fertilizers are amazing, my favorite is BioAdvanced 12-Month Insect Killer and Fertilizer.

This great fertilizer is not only fertilizer but also a pest repellent. For young trees, this is a game-changer, because insects and pests can kill your tree. Even older trees can succumb to too many insects (we lost a pear blossom tree this year, and it was devastating).

This fertilizer protects against Japanese beetles, aphids, caterpillars, and more. Insects can become a huge problem with trees because you can’t reach them to remove them. If there were aphids in my tomatoes, I could do my best to physically remove them and then treat the plants. With oak trees, you usually have to remove what you can reach and hope for the best.

Not anymore, though!

This slow-release fertilizer protects and feeds for up to 12 months, which is awesome if you tend to forget about your trees like I do. I know that my focus is usually on needier plants, so I tend to neglect my trees. Thanks to this fertilizer, I don’t have to worry about that anymore.

I like this product the best because the 2-1-1 nutrient composition is gentle enough for various shrubs and smaller, potted trees, as well as young transplants. If you’re planning on adding some new oaks to your yard, I highly recommend this fertilizer.

It also comes with a built-in measuring cup. I really love this because this is an inorganic fertilizer, and I don’t want to be measuring it with my kitchen measuring cups. Kitchen utensils and gardening should pretty much never mix, so the built-in measuring cup is a great little addition that makes gardening that much more convenient.

My only qualm with this fertilizer is that it’s granular, and usually, I don’t like them. If I have to use a granular fertilizer, I like to mix it into the soil to prevent crusting. It’s also super easy to transform granular fertilizer into liquid if you’re wary about granular products like I am.

Because of the gentle nutrient ratio and convenient packaging, it’s pretty much impossible to mess this up when using this product. So for even the most inexperienced gardeners out there, this is a great product to use. Keep reading to learn more about some other awesome oak fertilizers.

Top 5 Best Fertilizers For Oak Trees

In a hurry? Check out our top 5 picks below! Keep reading to learn more about these wonderful fertilizers for your oak.

  1. BioAdvanced 12-Month Insect Killer and Fertilizer (My Top Pick)
  2. Humboldts Secret Tree Trunk (My High-End Pick)
  3. Jobe’s Tree Fertilizer Spikes (Best Product For Mature Oak Trees)
  4. Scott’s Evergreen Flowering Tree & Shrub Continuous Release Plant Food (Best Granular Product)
  5. Miracle-Gro Tree & Shrub Plant Food Spikes (Most Popular and Convenient Product)

Why Should You Invest In A High-Quality Fertilizer For Your Oak Tree?

Oak trees are pretty hardy, I’ll admit. Most of the time you can just stick ’em in the ground and wait. And wait, and wait, because trees take forever. In my opinion, that makes the shade feel even sweeter, knowing you directly care for the tree that provides it.

Investing in a high-quality fertilizer will help keep your oak tree happy and healthy. It strengthens their roots, keeping them firmly planted in the ground. If you live somewhere with nasty storms, this is especially important. You definitely don’t want an oak falling on your car, or worse, your house!

Invasive species decimate our trees every year, and a lot of tree fertilizers (like my top pick) help to protect against them. Like I mentioned before, we lost a pear blossom tree last year due to spotted lantern flies, and my mom is already worrying about our maples this season. Losing a tree to insects stinks because there’s really nothing you can do.

Paying to have a dead tree removed is also expensive! It can cost thousands, depending on how many trees you lose and how big they are. Trust me, it’s way cheaper to invest in a high-quality fertilizer instead.

High-quality fertilizers can help your oak reach out, too. If you’re looking for a shady backyard (I mean literally shady, not guy-standing-in-a-dark-alleyway shady), then fertilizing your oak can help you reach that goal. Fertilizers with a high nitrogen content promote leaf growth, which means more relief from the sun for you.

That being said, it’s important to prune your oak tree when it starts to grow too wild, especially if you’re growing them for the aesthetic. Check out this video on how and when to prune your oak:

(Pruning sealer can be bought from Amazon or just about any home-improvement store or gardening center).

I definitely recommend pruning your oak if you want it to grow in a certain direction. Want it to grow up, rather than out? Prune low-hanging branches to encourage upward growth. If your trees are getting too tall, I recommend calling a tree service or an arborist to help you out. They are the professionals, after all, and this is something you definitely don’t want to mess up.

A high-quality fertilizer will also have a balanced and specifically formulated ratio of nutrients. All of the fertilizers on this list are made just for oaks and other trees but of course, you can buy fertilizers specific to just about any kind of plant. I recommend buying fertilizer that’s specific to your type of plant (for example, buying a specially formulated plumeria fertilizer) to get the best results.

Keep reading to learn more about the specifics of choosing the right fertilizer for your oak tree to keep it happy and healthy.

How to Pick the Best Fertilizer For Your Oak Tree?

Composition

I know I mentioned some of the most important components of fertilizer earlier, but an in-depth knowledge of fertilizer composition is vital not only for happy trees but also for a healthy garden in general.

Like I touched on earlier, fertilizer is composed of three main ingredients: nitrogen, phosphorus, and potassium. Any fertilizer you buy will have three numbers representing these three ingredients (they look like this: 10-10-10).

A good fertilizer for your oak tree will have a higher nitrogen content since nitrogen promotes green, leafy growth. For example, my top pick on this list has a ratio of 2-1-1. The higher concentration of nitrogen promotes leaf growth, and since the goal of a tree is to grow leaves, this formula is perfect!

There’s no need to stress over the numbers on your fertilizer, though. A little more phosphorus or potassium won’t hurt your oak—in fact, it probably won’t affect it at all. As long as there’s a decent amount of nitrogen, you’re good to go.

Any of the fertilizers in this article are great for your oak and are designed specifically for happy and healthy trees. Like I said, don’t stress, cause I’ve got you covered with these fertilizers.

Organic Versus Inorganic

In my experience, organic fertilizer is almost always better than inorganic, especially when dealing with edible plants. Since people don’t really eat oak trees, you don’t need to worry too much about this, but it’s important to know anyway.

The majority of these fertilizers are inorganic because, like I said, people don’t really eat oak trees. They also contain insecticides to deter harmful pests. Since it’s important to know the difference, let’s get into the specifics anyway.

“Organic” means exactly what you think: all-natural. It doesn’t mean it’s safe to eat, but it is safe to apply to plants that you eat, and less likely to crust on the soil or burn your plant. Fun fact: you can actually make your own organic fertilizer at home from kitchen scraps. However, you won’t get some of the perks of inorganic fertilizers such as pesticides.

Pesticides are a huge perk to have in your oak tree fertilizer because oaks are so prone to insect infestations. And contrary to popular belief, inorganic fertilizers won’t harm your plants (when used properly, of course).

It can be easy to make a mistake, though. The hot sun can react with the added chemicals and burn your plant, or cause the fertilizer to crust on the top of the soil.

I recommend reading up more on the similarities and differences between organic and inorganic fertilizers. It’s good gardening information to know, even if it doesn’t matter too much for your oak trees. Now let’s get into the specific products!

My Reviews of the Best Fertilizers For Oak Trees

1. BioAdvanced 12-Month Insect Killer and Fertilizer (My Top Pick)

Despite my usual aversion to fertilizers with insecticide, I love this long-lasting product!

The insecticide helps to protect your tree from harmful pests such as aphids, caterpillars, and Japanese beetles, which is good news as more and more invasive species seem to make their way into our backyards.

While the 2-1-1 nutrient composition is gentler than most products, it will still encourage your oak to produce healthy leaves and provide shade for your backyard. It’s also slow-releasing, providing protection and fertilization for up to 12 months.

I love the built-in measuring cup that makes using this product so easy. It eliminates the need to use kitchen measuring cups in the garden, and considering the fact that this product is not organic, it’s safer, too.

The only downside to this product is that it’s toxic to pets. Make sure they don’t go near the application site for at least 24 hours after applying, or it could make them really sick.

PROS (+) CONS (-)
+ Slow-releasing formula
+ Limited application necessary
+ Comes with a built-in measuring cup
+ Gentle nutrient composition is good for young trees
+ Protects against harmful insects and pests
– Pets must be kept away for 24 hours after application
– Nutrient composition can be too gentle for more established trees

2. Humboldts Secret Tree Trunk (My High-End Pick)

This product is my high-end pick, but I think it’s great for your oak!

This fertilizer is designed specifically for tree trunks, which is why the nutrient formula is 0-0-2. It encourages strong growth in the trunk and branches, which helps to protect against storm damage.

It’s a liquid fertilizer, which means no crusting on the top of the soil. All you have to do is mix 1 teaspoon into 1 gallon of water and you’re all set!

For larger oaks, I would use this maybe once a month; for smaller oaks, use every week or two to really promote strong growth.

The only downside is the nutrient composition. I wish it had nitrogen in it as well to promote leaf growth, but you do need the trunk to be healthy before you can have lush leaves.

PROS (+)CONS (-)
+ Strengthens the trunk of your tree
+ Liquid form
+ Quick results
+ Easy to use
– Potassium silicate only
– Should be used often on young trees for good results

3. Jobe’s Tree Fertilizer Spikes (Best Product For Mature Oak Trees)

Do I obsess over using fertilizer spikes? …yes, yes I do.

I also obsess over Jobe’s products—they pretty much have fertilizer for everything you could ever grow, including these fertilizer spikes made specifically for trees and shrubs.

I love fertilizer spikes because they’re the only type of fertilizer that can be removed from the soil. Should your oak respond poorly, you can just take the spike away. Some of the nutrients will remain in the soil, but for the most part, any damage is reversible. You won’t have a problem with this product, though!

These 15 fertilizer spikes are also a good deal, at around $0.66 per spike. If you only feed three trees twice a year, this single investment will last you over two years. That sounds like a good deal to me!

The 16-4-4 nutrient composition is much stronger than the previous products, and so I find this product to be better for more established oaks. You’ll be seeing a lush canopy of leaves overhead in pretty much no time, though! These spikes also feed all season long, so you don’t have to worry about constant application or keeping a calendar.

The only downside is that you can’t exactly tailor the amount to your oak’s needs. A spike is a spike. If these are too harsh for your oak, there’s not a whole lot you can do. Again, I don’t think you’ll have a problem, especially with established trees, but it’s just something to think about.

PROS (+) CONS (-)
+ Easy to use
+ Strong nitrogen content
+ Slow releasing
+ Can be removed from the soil if tree responds poorly
+ Budget-friendly
– Can’t tailor the amount to your tree’s needs
– Nutrient composition might be too strong for young trees

4. Scott’s Evergreen Flowering Tree & Shrub Continuous Release Plant Food (Best Granular Product)

I love granular fertilizers when I’m working with larger plants such as oak trees, which is why Scott’s Evergreen, Flowering Tree & Shrub Continuous Release Plant Food is a recommendation of mine.

The 11-7-7 nutrient composition is the perfect middle-ground of all these products. It’s got a relatively even dose of nitrogen, potassium, and phosphorus, without being too strong.

It’s great for your oak (don’t be fooled by the label!) and is slow-releasing, feeding for up to 2 months. That means fewer applications you have to worry about, which as a forgetful gardener, I love!

This is my favorite granular fertilizer because it won’t burn your tree or crust on the soil, which can both be problems with granular fertilizers sometimes.

The biggest downside to this product is that it can be pretty potent. Be careful not to overdose young trees; I recommend using half the directed amount for your first application.

PROS (+)CONS (-)
+ Slow-releasing formula
+ Lots of nutrients to promote well-rounded growth
+ Resealable bag for safe storage
+ Won’t burn your tree when used properly
+ Budget-friendly
– Can be too strong for young trees
– Not made specifically for oaks

5. Miracle-Gro Tree & Shrub Plant Food Spikes (Most Popular and Convenient Product)

I know, I know, another fertilizer spike. What am I thinking?

I was thinking that this is a great product, of course! Everybody knows Miracle-Gro, and I believe in putting products on this list that are familiar to everybody, regardless of gardening experience. It’s by far the most well-known product on this list, and for good reason!

The 15-5-10 nutrient composition is strong enough for even mature trees, and the high nitrogen content means more shade and sooner. I recommended this exact product to my family since we have fair skin, and man do we burn easily!

Plus, who doesn’t love fertilizer spikes? They’re mess-free and perfectly self-explanatory; just stick them in the ground near the base of your tree (check the packaging to see how many to use) and you’re done.

You only need to feed your tree once in the spring, and once in the fall, which is great for people like me who tend to forget that trees need fertilizer, too. By plugging the nutrients right next to the roots, you also ensure that your oak gets exactly what it needs, sooner.

The only downside of this product is that it’s easy to overdose your tree, especially if it’s younger or less established. You can, of course, always take the spike out, though.

PROS (+)CONS (-)
+ Trusted brand
+ Easy to use
+ High nitrogen content to promote leaf growth
+ Minimal applications necessary
+ Slow-releasing formula
– Easy to overdose your tree
– Can’t tailor the amount for your specific tree

My Top Pick: BioAdvanced 12-Month Insect Killer and Fertilizer

In my opinion, you can’t find a better fertilizer for your mighty oak than BioAdvanced 12-Month Insect Killer and Fertilizer.

Usually, I steer clear from inorganic fertilizers, especially ones with insecticide, but this fertilizer is fantastic for dealing with pests that can kill an otherwise healthy tree. Because oaks are so hardy (and large… and expensive to replace if they’re killed by pests) this fertilizer gets my seal of approval.

I also love how convenient it is to use. Once a year application with a built-in measuring cup, and measurement ratios on the bottle? Sign me up!

The nutrient ratio is gentle for young trees, at 2-1-1, but still promotes strong and healthy growth. Before you know it, you’ll be relaxing in the shade of a tall and mighty oak. With this fertilizer, there’s no need to worry about harmful pests or an unhappy tree.

Final Thoughts On The Best Fertilizers For Oak Trees

Oak trees are a beautiful and shade-creating addition to your backyard. For people who burn easily, they’re built-in protection from the sun, and man do I love them for that.

With proper fertilizer, you’ll be growing magnificent oak trees before your eyes, which is really fast for a tree! With insecticide in your fertilizer, you’ll also protect your oak from harmful pests.

The right fertilizer can and will help your oak thrive to its fullest potential, providing you with ample shade and a beautiful sight to see. So set up your hammock, kick back, and relax in the shade of your healthy, happy oak tree!

Emma Grace

Emma Grace

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Emma Grace

Emma Grace

About Learn Planting

Here at Learn Planting, I review the best planting tools and products so that you can get everything you need to create your vibrant garden, whether indoors or outdoors!

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