23 Plants Not to Grow Under A Pine Tree

The space beneath the towering, majestic pine tree in your backyard is beckoning you to plant something beneath it. Let’s be honest, you would like to grow a plant there as well! Hold up — before you get started, you should know that there are some plants that you should NOT grow under a pine tree.

Pine trees grow best in acidic soil. They have shallow root systems and create a lot of shade. Because of this, many plants, including potatoes, carrots, lettuce, tomatoes, onions, cucumbers, broccoli, peas, zucchini, peppers, poppies, zinnias, cosmos, and roses, do not grow well under pine trees.

For your pine tree to thrive, some plants will have to go to the other end of the yard. Before we list some of the incompatible plants, let’s talk about the factors that cause the incompatibility: acidic soil, too much shade, and a shallow root system.

What Does It Mean When Trees Are Acidic Or Basic?

To understand what this means, we need to rewind to chemistry class. (Don’t worry — there’s not a test, and this concept doesn’t involve complicated calculations.) It all has to do with soil pH level.

The pH scale goes from 0 to 14. The middle of the scale, 7, is neutral. Pure water (with no other additives, minerals, or contaminants) is considered a 7 on the pH scale.

If a substance has a pH below 7, it is considered an “acid”. Some common examples are lemon juice (pH 2.3) and vinegar (pH 3.3). But even milk (pH 6.4-7.6) can be slightly acidic.

On the pH scale, basic does not mean boring. “Basic” means the substance had a pH above 7. Baking soda (pH 8.2) and ammonia (pH 11.0-11.5) are good examples of common bases.

This scale does not work in a linear fashion like a thermometer does. Every time you move down a unit on the scale, the pH is multiplied by 10. So a pH of 5 is ten times more acidic than a pH of 6.

Why does this matter in your garden? According to Cornell University, pH is a crucial part of plant longevity. Nutrients from the soil must be dissolved in water for plants to absorb them.

If the soil is too basic, water might not be able to dissolve the micronutrients that plants need to thrive. But if the soil is too acidic, it can dissolve too many nutrients.  

Yes, you can have too much of a good thing! Just like over-watering or dumping on too much fertilizer, the nutrient overdose from acidic soil is TOO MUCH for plants. 

If you’d like to learn more about pH, take a peak at our piece on what specific pH level trees like for growth!

Pine Trees Love Acidic Soil – But Don’t Make The Ground Acidic

You may have heard before that pine trees make the surrounding ground more acidic. According to the University of New Hampshire, this is a myth. Pine trees do not create acidic soil.

While it is true that pine needles themselves are acidic once they have fallen off the tree, they will not make your soil more acidic. As the needles decompose, they slowly become neutral. (They make good mulch if you’re looking to repurpose the gift your pine tree keeps bestowing upon your yard.)

A study published in Hort Technology showed that if a pine tree is used as a substrate (ground up into pieces to serve as a makeshift soil), it would still need additional fertilizer to be acidic enough to sustain plant life. 

This is a classic case of “correlation does not equal causation”. Pine trees don’t cause the soil to become acidic. They grow well where they do because the soil is already acidic.

How To Determine Your Soil pH Level

Before you plant ANYTHING underneath your pine tree, you need to check the soil pH. If your tree is already struggling to grow in alkaline soil, the last thing it needs is competition from other plants.

There are clues as to what your soil pH may be (like mixing the soil in vinegar or baking soda to see how it reacts), but these methods can be unreliable. You can only know your soil pH level for sure if you take the time to measure it. 

Measuring doesn’t have to be hard. Take a look at this Digital Soil Meter!

Instead of messing around with litmus paper, you just poke the probe into the soil you would like to test. It’s reusable and also has options to measure the temperature and water content as well. 

If you would rather not use a probe, litmus paper is an affordable, tried-and-true method of testing pH levels. This also works well when measuring the pH of something that you cannot probe. 

How Can I Change My Soil pH Level?

Every year, gardeners and farmers across the world modify their soil in an attempt to meet their plants’ needs.

Even though this is a common practice and often involves using natural substances like limestone and wood ashes, changing the pH of your soil is still a chemical reaction. Please ask a professional if you need help determining your soil pH. Your local garden center is an excellent resource!

Let me say it again. Do not attempt to use soil modifiers unless you have determined your soil pH. You can irreversibly damage your plants if you make an incorrect modification.

This can devastate large trees. Check the soil pH every time you add anything to the soil because it will change over time. 

If you have determined that your soil needs to be more acidic, there’s a relatively simple solution. According to Clemson University, the two most common ways to make your soil more acidic are to add either aluminum sulfate or sulfur.

A product like this Bonide Aluminum Sulfate instantly makes the soil more acidic because it does not need to convert into another substance.

Something like the Jobe’s Organics Soil Acidifier, on the other hand, needs time to turn soil acidic because it must convert into sulfuric acid. 

Remember that permanently changing the pH level of your soil is impossible. The conditions that existed before you added soil modifiers will continue to exist afterward. Gradually, the soil will revert to what is “normal” for your area. Only change the pH if you are prepared to add modifiers continually.

If you try to grow something next to your pine tree that has incompatible soil needs, either that plant or the pine tree will suffer. 

Maintaining acidic soil is of paramount importance to your pine tree’s longevity – but it’s not the only factor that determines what plants grow best beneath it!

If you’re in need of a fertilizer, or having problems with your pine, take a a look at our guide on why your pine tree isn’t growing here!

Why Plants Usually Don’t Grow Well Under Pine Trees

If it seems like pine trees are more likely to fall over in a windstorm, it’s not just your imagination. Pine trees have a dense network of shallow roots. This means that they are more likely to topple in a hurricane-force gust. This also makes it almost impossible for other plants to form a strong root foundation.

Even though they’re hidden underground, roots are essential for a healthy plant. Roots are how water and nutrients are absorbed. If a plant has unhealthy roots, it will not get the minerals it needs to survive.

If you’ve ever seen a large grove of pine trees with no other plants underneath, it’s possible the pine tree roots crowded out all other competition. Don’t let that happen in your garden.

One of the greatest adventures in landscaping is that no matter where you live, you can attempt to grow anything. However, your yard will be healthier if you work with Mother Nature rather than against her. 

Pine trees need acidic soil, produce lots of shade, and need space close to the surface for their roots. With that said, here are 23 plants NOT to plant beneath your pine tree.

By the way, if you’re a bit over your pine, check out our piece on the reasons you should cut your pine tree down!

What Not To Plant Under Your Pine Tree

Potatoes

Although they both prefer acidic soil, potatoes and pine trees are not friends. The pine tree’s network of roots runs along the surface of the soil.

This prevents potatoes from forming the dense, deep root system they require to form large spuds. Put the potatoes somewhere else.

Carrots

Carrots can handle the acidic soil that pine trees like, but they need more room than is available.

Similar to potatoes, carrots do most of their growing down rather than up. The roots of a pine tree will strangle and crowd out any carrots that try to grow. Plant your carrots somewhere with deeply tilled earth. 

Lettuce

Lettuce has a shallow root system, so you might be tempted to see if it will cooperate with a pine tree’s web of roots.

Before you plant a salad garden under your pine tree, remember that pine trees prefer soil that is far more acidic than what lettuce will tolerate. Lettuce also needs direct sunlight or the leaves will not form correctly.

Tomatoes

Tomatoes are not as picky about soil pH as other plants, but they need the sun for the fruit to ripen properly.

Unless you like yellow leaves and sickly, green tomatoes (assuming the plant is even healthy enough to produce fruit), skip this one.

Onions

Onions grow under the ground, forming the bulb that we eventually harvest and eat. Pine tree roots will crowd out your onions.

Grow your onions in a big garden space where they are free to grow big and round!

Corn

Similar to pine trees, corn plants have shallow roots. This makes it so that they can quickly absorb water.

All the water in the world won’t make up for the lack of sun under a pine tree, though. Corn needs bright, direct sunlight to produce large, juicy ears. 

Pumpkins 

Pumpkins need a massive area to spread their vines. Could the vacant space under your pine tree be a good match

Sadly, although pumpkins tolerate the acidic soil, this is the wrong place if you want large gourds for Halloween.

There is not nearly enough sunlight underneath the boughs of a pine tree.

Beans 

Beans come in many varieties, so you would think that at least one of them would tolerate the acidic soil that accompanies a healthy pine tree.

Unfortunately, beans need soil that is far more alkaline. They also need strong, direct sunlight. This would not be a good companion for your pine tree.

Cucumbers 

Cucumber vines thrive in acidic soil, so you would think that they would do well with a pine tree as a neighbor.

But like other vegetables, cucumbers need more than the heavily filtered sunlight that sporadically shines through the needles of your tree. 

Zucchini

Zucchini is a resilient vegetable that seemingly grows itself. It’s a wonderful plant for a first-time gardener.

However, pick a different spot than under the pine tree. Zucchini can tolerate a variety of soil pHs, but sunlight is non-negotiable. 

Peppers 

Peppers can handle acidic soil better than other vegetables, but it is not nearly sunny enough underneath a pine tree for them to do well.

Not to mention the competition your pepper plants’ roots will face! Find another spot in your yard.

Broccoli 

Unlike other vegetables, broccoli tolerates shade and cooler temperatures quite well. It’s just too good to be true, though!

The soil is too acidic underneath a pine tree for broccoli to thrive. 

Peas 

Peas are some of the earliest seeds to germinate and produce vegetables in the spring.

Could their cold-weather tolerance handle the cool shade of a pine tree? Unfortunately, they need more sun that is typically available under a pine tree.

On top of that, the soil that a pine tree likes best is far too acidic for peas. Try growing your peas somewhere else.

Poppies

If vegetables don’t do well under a pine tree, perhaps flowers will perform better. It doesn’t look like we’re off to a great start, though.

Poppies find the soil to be far too acidic. For poppies to grow well, you would have to make the soil more alkaline.

This would hurt your pine tree.

Zinnias 

Zinnias come in various colors and not only tolerate but need acidic soil. Could this pop of color be the solution to your shady, barren landscape? Not quite.

Zinnias would struggle with the lack of sunlight under a pine tree.

If only the shade wasn’t so dense!

Cosmos

Cosmos is not only a Neil deGrasse Tyson documentary series about outer space — it’s a simple flower that will make your yard look out of this world!

But although cosmos flowers would get along perfectly with a pine tree in terms of acidity, it simply needs more sun to survive.

Firebush

Hummingbirds love the flowers on this vibrant red shrub. But this is regrettably not a good match for your conifer.

Don’t extinguish the firebush by dooming it to the shade. Save it for a sunny, alkaline portion of the yard.

Dianthus

The most popular variety of this spunky flower is referred to simply as “Pink”. Don’t get your hopes up, though.

The shade from your pine tree is too much for the dianthus to handle.

Bright flower gardens will need to be located somewhere else!

Indian Hawthorn

This evergreen bush will stay green all winter, just like your pine tree! Unfortunately, that’s where the similarities end.

Indian hawthorn requires alkaline soil and will not do well when planted next to a pine tree. This plant really needs enough space to form a solid root ball. 

Roses

Roses are a romantic flower that can brighten up any garden! But this love story has a sad ending.

Although roses tolerate acidic soil just fine, it is too shady and there is not enough root space if it is planted under your pine tree.

Sunflowers

Sunflowers are hardy flowers that have a reputation for blooming where they are planted.

Look along the highways in late summer—the sunflowers you see lining the road were not planted by transportation department gardeners.

Birds spread the seeds, and the sunflowers took root in the poor soil along the shoulder!

Despite its resilience in the gravel along the sunny highway, however, sunflowers will wilt in the shade of your pine tree.

Daffodils

Some of the first flowers to appear in the spring, daffodils resemble a horn and metaphorically trumpet in the arrival of spring.

If you plant daffodil bulbs under your pine tree in the fall, however, they won’t sprout in the spring. The soil acidity is fine, but there’s not enough sunlight.

The snow in the shade of your tree will be among the last to melt, covering your daffodils and leaving them behind.

Tulips

Tulips are another spring bulb that is planted the preceding fall. Similar to daffodils, these bulbs will not end up sprouting.

The shade will cause issues with the ground warming up enough for the bulbs to germinate.

Also, tulips have different pH requirements than daffodils. The soil under a pine tree is far too acidic for tulips.

What PlantsWill Do Well Under A Pine Tree?

After reading about two dozen plants that won’t work with your favorite needled tree, you might be tempted to think that nothing can grow in the barren dirt underneath your tree.

However, now that you know what won’t work, think in terms of opposites to identify species that will do well. 

If you look at the coniferous rainforests of the Pacific Northwest, you will notice that other plants do, in fact, grow underneath the pine trees in that climate.

Some of the most noteworthy examples include wild huckleberries (for which the area is famous) and wild blueberries.

Once again: It is possible to grow plants under your pine tree. You just need to pick the right kinds.

Plants that tolerate shade, acidic soil, AND limited root space will not only survive but thrive under your pine tree. Steer clear of these 23 plants in the list above and your tree will be happy and healthy for years to come!

References

Ward, D. Shade is the most important factor limiting growth of a Woody Range Expander. PLOS ONE.

Wright, R., Jackson, B., Browder, J. F., &; Latimer, J. (1970, January 1). [PDF] growth of chrysanthemum in a pine tree substrate requires additional fertilizer: Semantic scholar. undefined.