If ever there were a stately tree to dominate your yard, it is the mighty oak tree! These attractive trees provide shade, food for wildlife, and beautiful fall colors. If you would like to add some color to the space under your oak tree, there are a few plants you should make sure NOT to grow under your oak tree.
Plants that need full sun, high nutrient content in the soil, and lots of water won’t do well under an oak tree. Never grow english ivy, bee balm, hibiscus, chrysanthemum, peonies, marigolds, asparagus, pumpkin, squash, lisianthus, or butterfly bush under an oak tree as they will grow poorly.
Whether your oak tree is a massive statement piece or just getting started, we’ll go over the plants you can and can’t grow underneath an oak tree. Let’s get to it!
Why Is It Difficult To Grow Plants Under An Oak Tree?
Some trees produce plant toxins that can inhibit other nearby plants from growing. Other trees only grow in harsh conditions, preventing other plants from growing under them.
You won’t have these sinister problems with oak trees. However, depending on the species, oak trees will take up a lot of nutrients and water and they’ll cast a ton of shade.
In general, you don’t want to plant anything that requires the following conditions:
- Full sun
- High nutrient content
- Ample water
- pH sensitivity
Instead, opt for plants that are shade-tolerant, low-maintenance, and drought-tolerant. But don’t worry, we’ll get to those plants a little later in the article!
In addition to competing for sun, nutrients, and water, the plants under your oak tree should be able to thrive in a variety of pH conditions.
The reason is that oak trees contain the chemical tannin, which over time, can turn the soil slightly acidic. (you can read more about why acidic oil can be good for trees here.)
All in all, this takes a long time and shouldn’t be expected in new oak trees. However, if your oak tree is old, the soil may be more acidic than when it first started growing!
According to an article in the Journal of Plant and Soil, tannins were originally thought to deter herbivores from eating certain plants, but this take on tannins has recently been called into question.
Instead, researchers now think tannins are used to protect the plants from possible afflictions. More specifically with fruits – from getting eaten before the seeds are ready for dispersal!
Nonetheless, over time, tannins can turn the soil’s pH acidic and contribute to the reduced productivity of surrounding plants.
Most oak trees prefer the soil to be slightly acidic, but if you find your soil is too acidic, you can always use something like Jobe’s Additive De-Acidifier Lime Soil to help bring the soil back to a more neutral pH.
On the other hand, if your soil appears to be too basic, you can add an acidifier like Jobe’s Organics Soil Additive Soil Acidifier.
Performing a simple soil test will help you identify the pH of your soil and some other important characteristics, such as the nutrient content and soil type.
Plants You Should Never Grow Beneath An Oak Tree
According to Michigan State University, there are around 600 different species of oak trees. That’s a LOT of variety!
With this vast differentiation comes different preferences for soil, sun, and nutrient conditions. Some oak trees thrive in swampy conditions while others need dry, well-draining soil. Oak trees differ in their hardiness tolerance as well.
The point is, there’s no one-size-fits-all when it comes to oak trees. So, not every plant on our list is going to apply to your situation.
However, we tried to cover the most common oak tree species paired with some of the most common plants known to homeowners and gardeners alike.
As a quick side note, I highly recommend taking a look at our how to article on tips for watering your oak tree, especially if you have a garden!
As the name suggests, English ivy is an evergreen vine. These perennials are considered groundcover plants when they are young but will climb once they get established.
English ivy thrives in part shade, which is what you’ll find under your oak tree. BUT, the reason we put this plant on our list is that it will cause your oak tree a lot of problems.
If planted under your oak tree, this vine will take over FAST. It grows quickly and can creep up your oak tree’s bark, loosening it. According to the University of Maryland, English ivy can also promote leaf scorch, which is a bacterial affliction prevalent in oak trees.
If you really want to plant English Ivy under your oak tree, it will need constant pruning to ensure it doesn’t end up overtaking your tree.
If it ends up getting out of control, you can read about what to do if you have vines on your oak tree here to help solve your problem!
Also known as bergamot or horsemint, bee balms are part of the mint family. These perennials produce pretty flowers from July through August.
But don’t let the pretty flowers lure you into planting these under your oak tree!
Bee balms prefer full sun and can become susceptible to powdery mildew if planted in part shade. They will also not flower as much if planted in the shade.
Bee balms are quite fond of water and need watering at least once a week. While competing for water resources with an oak tree, you would most likely have to increase the watering schedule.
While bee balms aren’t the WORST plant to plant under an oak tree, there are plenty of better choices out there.
For those who live in warmer climates, hibiscus may seem like a staple in the landscape. It boasts huge, beautiful flowers that come in a variety of colors.
Sounds great, right?
The problem with hibiscus is that it requires a lot of nutrients and it requires full sun to bloom properly.
According to the University of Minnesota, hibiscus are heavy feeders that require a complete fertilizer through the entire growing season to keep them in tip-top shape. Hibiscus also does best in full sun and may struggle to bloom if placed in shady areas.
Some hibiscus species will perform better than others under an oak tree. For example, hardy hibiscus will survive under an oak tree, but it won’t thrive. Tropical hibiscus will struggle even more under the magnificent shade of an oak tree.
More commonly known as ‘mums,’ chrysanthemums are known for giving homeowners a blast of color in the fall, while everything else around them is slowing down and going dormant.
We put the added ‘perennial’ for a reason. Many homeowners will plant mums in the fall and treat them as annuals. They give off a blast of color for a few weeks and then they’re spent, not to bloom again next year.
Annual mums are totally fine to be planted under your oak tree. Mums are heavy feeders, but an established oak will not be affected by a plant that only lasts a few weeks. Despite preferring full sun, annual mums will do okay for one season in partial shade.
However, if planted in the spring in colder climates (or if you live in warmer climates), mums can be treated as perennials that will come back each year.
It’s these perennials you need to watch out for!
According to Clemson University, perennial mums are heavy feeders that will compete with your oak tree for nutrients. This can be especially damaging if your oak tree is young. Mums also require plenty of water, which can make them difficult to grow under an oak tree.
Besides their heavy nutrient and watering requirements, perennial mums will do poorly in the shade after their first year.
Peonies boast huge flowers in the spring and summer that vary in color. The flowers are sometimes so big that they can topple over the stems.
These beautiful plants are perennials that will come back year after year, just not under your oak tree!
Peonies are water and nutrient hogs. They don’t play well with other plants, especially trees that are likely to take up most of the nutrients and water they need to thrive.
Another challenge with planting peonies under an oak tree is the access to sunlight. Peonies are known for their amazing blooms, and if not given enough sun, the blooms will be lackluster.
Marigolds are annuals that are considered easy to grow. They come in a host of different colors and varieties and tolerate drought and extreme heat.
However, one thing marigolds can’t tolerate is shade. According to the University of Minnesota, marigolds require full sun to bloom properly. In fact, it’s recommended to keep them in the sun all day long.
Oak trees will cast too much shade for marigolds to thrive. They are unlikely to bloom as well and may contract powdery mildew if left in a location that’s too shady.
You can read more about that in our guide on why marigolds need full sun!
Most of the plants you want to put under your oak tree will be landscape flowers. Annuals, perennials, shrubs, that sort of thing.
This one is for the gardener who has an oak tree within the immediate vicinity. There are a few vegetables you may want to nix in your garden if you have an oak tree nearby, and asparagus is one of them.
Unlike some garden veggies, asparagus is a perennial that will keep coming back year after year. They require full sun – at least 8 hours according to the University of New Hampshire.
In addition to needing more sun than the space under an oak tree can provide, asparagus are also heavy feeders. They require a complete fertilizer worked into the soil before and during planting.
This makes them a poor candidate to plant under an oak tree. But there are still plenty of garden vegetables you can plant if you have an oak tree nearby. More on that later!
Pumpkins & Squash
Pumpkins and squash are other vegetables that will not do well under an oak tree. These annual vines are sensitive to frost, so will do best in warmer climates or if planted late in the spring.
Pumpkins and squash require lots and lots of sun, making them a less-than-ideal plant to place under an oak tree.
Another challenge is that pumpkins and squash require a lot of water to grow properly. According to the Maine Department of Education, pumpkins are 90% water!
When competing with an oak tree for water, pumpkins and squash don’t stand a chance unless you take the time to water them thoroughly each day.
Also known as Texas bluebell, this beautiful purple flower is becoming more and more popular with experienced gardeners and green thumbs alike.
Why experienced, you might ask? Well, this pretty flower is also a LOT of work to grow. Because of its demanding growing conditions, it’s not a great choice to plant under your oak tree.
Lisianthus can be even more difficult to grow under established oak trees because the soil may be acidic. According to the University of Arkansas, this can cause zinc toxicity in Lisianthus, which will stunt growth.
Despite its beautiful purple flowers, there are easier, less demanding flowers out there that you can plant under your oak tree.
As the name suggests, butterfly bushes attract butterflies, bees, and hummingbirds. These colorful bushes produce attractive purple flowers from summer through fall.
Butterfly bush checks off almost all the necessary boxes to plant under an oak tree. They thrive in a variety of conditions, require minimal care, and are readily available at garden centers or nurseries.
The problem? These plants can GROW. And grow and grow and grow! They produce a ton of seeds each year and can quickly overtake the space under your oak tree.
Like English ivy, butterfly bush is not a good choice unless you are willing to have this plant spread.
One more barrier that prevents butterfly bush from being a good plant under your oak tree is its sun requirements. Butterfly bush does best in full sun if you want to see their beautiful flowers.
What Plants Can Live Under An Oak Tree?
We’ve gone over annuals, perennials, bushes, and even some vegetables that won’t perform well under an oak tree.
So, what can you plant under an oak tree?
For flowers and vines, try to stick with some of the below plants. They tolerate shade and require minimal care:
- Fern (Try Christmas for cold climates and sword ferns for warm climates)
- Wild ginger
For vegetables that work well under your oak tree, consider these low-maintenance, partial-shade-tolerant vegetables and herbs below:
With proper care, these flowers, vegetables, and herbs will thrive under your oak tree. Always make sure your chosen plant can survive in your hardiness zone.
Ways To Help The Plants Under Your Oak Tree Thrive
Having an oak tree in your yard doesn’t mean you can’t plant something under it. There are plenty of things you can do to make sure the space under your oak tree looks stunning.
Below, we’ll cover some tips on what you can do to make the area under your oak tree more hospitable to some beautiful annuals, perennials, vines, and whatever else you have in mind!
Know Your Oak Tree
One of the first things you should do before planting anything under your oak tree is to identify what variety of oak tree you have.
While many oaks share the same characteristics, they differ from each other in a few, subtle ways, such as:
- Soil type preference (Sand, clay, loam, etc.)
- Moisture preference (swampy versus dry, upland soil)
- pH preference
- Root structure
- Drought tolerance
- Growth rate
If you can identify these characteristics, it will give you a better idea of the plants to pair with your oak tree.
Try to plant plants under your oak tree that need similar growing requirements for soil type, moisture, and pH preference. All plants planted under an oak tree should be somewhat drought tolerant.
Growth rate is another important feature of your oak tree that is good to know. If you want to landscape beneath a slow-growing oak tree, you’ll want to give it a few years to get established before even considering planting something.
Use Raised Beds
If you’re someone who has struggled to grow grass under your oak tree, you may be hesitant to even attempt flowers.
The reason nothing grows under an oak tree is that the roots are so close to the surface. In general, most oak tree roots are within the top 6 to 8 inches of soil.
Imagine you’re a little marigold trying to establish some roots and you run into a solid oak root! These roots make growing difficult for anything above them.
Because of an oak’s shallow roots, you can use raised beds to help give your chosen flowers some breathing room between their roots and the roots of your oak tree.
Be careful when constructing a raised bed, as you don’t want to smother the oak trunk in soil. You also don’t want to use fabrics or other materials to cover the space between your flowers and the natural soil. This can smother oak tree roots, which need to breathe.
Construct the raised bed far enough away from the oak trunk to give it space to grow, and place 1 to 2 inches of good quality soil in whatever shape or pattern you prefer. This should give your flowers enough space to flourish while preserving your oak tree.
Be Aware Of Your Oak Tree’s Needs
This section goes hand in hand with knowing your oak tree. But instead of focusing on what your oak tree prefers, we’re focusing on nutrients and water.
Oak trees that are just starting may benefit from having flowers planted around them, as the extra watering will help them grow. But for established oak trees, over-watering can stress the roots and even promote rot.
You can read more about why you shouldn’t water plants everyday here.
In terms of nutrients, planting a plant that is a heavy feeder that requires fertilizer could spell disaster for your oak tree.
A good NPK (nitrogen, phosphorous, potassium) ratio for oak trees is a 12-4-8 or 12-6-6 fertilizer. If you plant something that has other nutrient requirements, you could cause nutrient burn and harm your oak tree more than help.
Therefore, planting a low-maintenance, drought-tolerant, shade-tolerant plant will be your BEST bet under an oak tree.
That’s All For Now!
Having an oak tree in your yard is like having a piece of history close to home. These stately trees are long-lived and steeped in myth and lore.
While oak trees do just fine being exceptional on their own, adding a few low-maintenance flowers under your oak tree can add a splash of color in an otherwise barren area.
There are a few plants, vines, and vegetables that you want to stay away from when planting under an oak tree. Plants that are sun-loving, heavy feeders, or cannot tolerate drought are poor choices.
Now, for a quick recap!
The plants you should not grow under an oak tree include:
- English Ivy
- Bee Balm
- Perennial Chrysanthemum
- Butterfly Bush
Instead of these, opt for plants that thrive in partial to full shade, require little maintenance and care, and can withstand a little drought.
Best of luck on your oak tree journey!
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Demchik, M. C., & Sharpe, W. E. (2000, October 01). The effect of soil nutrition, soil acidity and drought on northern red oak (Quercus rubra L.) growth and nutrition on Pennsylvania sites with high and low red oak mortality. Forest Ecology and Management, 136(1-3), 199-207. https://www.sciencedirect.com/science/article/abs/pii/S0378112799003072
Kraus, T. E.C., Dahlgren, R. A., & Zasoski, R. J. (2003, September). Tannins in nutrient dynamics of forest ecosystems – a review. Plant and Soil, 256, 41-66.
Salminen, J.-P., Roslin, T., Karonen, M., Sinkkonen, J., Pihlaja, K., & Pulkkinen, P. (2004, September). Seasonal Variation in the Content of Hydrolyzable Tannins, Flavonoid Glycosides, and Proanthocyanidins in Oak Leaves. Journal of Chemical Ecology, 30, 1693-1711.