11 Plants Not To Grow Under A Sycamore Tree

Beautiful sycamore tree in autumn

Sycamore trees are the statement piece of any yard. Their massive height paired with mottled bark makes them an attractive tree. If you have one in your yard or are thinking of planting one, you may be wondering what you can and can’t grow under a sycamore tree.

Sycamore trees have a wide canopy, so any plants underneath will need to be shade tolerant and not compete with the tree. You should not grow impatiens, English ivy, coneflower, peonies, geraniums, delphinium, spider flower, astilbe, periwinkle, mums, and lupines underneath a sycamore tree.

Creating a landscape under a sycamore tree can be tricky. We’ll cover all the plants you can and can’t grow under a sycamore tree – so, without further ado!

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Why Is It Hard To Grow Plants Under A Sycamore Tree?

Sycamore trees are fast-growing, and they GROW. Mature sycamore trees typically reach a height of around 70 to 100 feet with a spread just as wide.

According to Clemson University, the American sycamore and London planetree (sycamore hybrid) are the two most widely used species in the landscape. They are often used to line streets since the London planetree is quite tolerant of pollution.

If you have one of these giant sentinels in your yard, you may find it a bit difficult to plant anything beneath. There are a few reasons why planting under a sycamore tree will test your patience.

Sycamore Trees Require A Lot Of Shade

Often times sycamore trees are grown in the yard to provide shade. With a huge spread, sycamores produce a lot of shade.

Any plant grown under a sycamore tree must be tolerant of shade. Even plants that are partial shade may struggle if not planted in the right space under a sycamore tree.

Sycamore Trees Leaves Are Massive

Sycamore leaves and seed pods in the sunlight

Sycamore trees are deciduous, meaning they lose their leaves in the fall. This can be a serious problem for anything planted under a sycamore tree for three reasons:

  • Leaf size
  • Effect of leaves on the soil
  • Leaf chemicals

The leaves of a sycamore tree are enormous, reaching up to 9 inches or more depending on the tree. As the leaves drop, they can blanket the area underneath, preventing the little amount of sun that will reach the plants beneath.

In addition to possibly shading out the plants under your sycamore tree, the leaves also decompose slowly due to their large size.

As the leaves decompose, they add nutrients to the soil, which can be beneficial to some plants but harmful to others.

Lastly, sycamore leaves are slightly allelopathic, meaning they exude chemicals that are meant as a defense mechanism against herbivores. As the leaves decompose in the soil, these chemicals are released and may affect sensitive plants.

When compared to other toxic chemicals such as juglone from walnut trees, the chemicals released in sycamore leaves are not as detrimental.

Sycamore Trees Have Shallow Roots (And Competition)

Sycamore trees grow fast, using their spreading roots to take up as much water and nutrients as they can while becoming established.

Their shallow roots mean there is going to be competition between the sycamore tree and whatever plants you decide to put beneath them.

Plants that require high nutrient content and lots of water will not do well under a sycamore tree. They may also steal vital water and nutrients that otherwise would go to the sycamore.

Sometimes too much competition can cause a sycamore tree to atrophy or rot. In these cases, you may need to cut down your sycamore!

Sycamore Tree Soil Conditions Don’t Favor Many Plant Types

Sycamore trees are very adaptable to different conditions. They aren’t picky about soil texture, PH, or moisture level.

An article in the Journal of Forests found that sycamore trees are often used to reclaim disturbed sites such as surface coal mines where soil conditions are poor and even toxic to other trees.

Because of this wide variety of adaptable conditions, sycamores may be growing in soil that isn’t conducive to certain landscape plants. The PH may be off, the soil texture may be wrong, or the soil may hold too much moisture.

A soil test will help narrow down exactly what conditions your sycamore tree is growing in. It can tell you the type of soil as well as the PH and nutrient levels.

Plants You Shouldn’t Grow Beneath A Sycamore Tree

In general, plants that require full sun, are heavy feeders, or require lots of water will not do well under a sycamore tree.

Let’s check out all the plants you shouldn’t grow under these massive trees.

Impatiens

We’re starting off with a flower that may surprise you. Impatiens do well in shade, so why can’t you plant them beneath a sycamore tree?

Impatiens can tolerate deep shade and will struggle if placed in full sun unless they are a full-sun variety. These annuals bloom in the spring and will produce flowers in a variety of colors.

The problem with impatiens is that they wilt quickly if drought-stressed. Being planted under a sycamore tree means the impatiens must compete for water sources.

If you are willing to consistently water your impatiens and provide them with plant food fertilizer, they might be able to survive under a sycamore tree. However, they will thrive better in a container on the porch or in a shady flower bed.

English Ivy

A European native, English ivy is an evergreen groundcover plant. If left unhindered, English ivy can creep up to 90 feet long, covering a substantial amount of ground.

English ivy is another plant that can tolerate the deep shade that would be found under a sycamore tree. The problem is that English ivy is invasive and will grow and grow and grow!

According to the University of Tennessee, English ivy will climb up the trunk of trees and eventually weigh down smaller branches and block sunlight.

Unless you are willing to put some serious work into pruning and trimming back English ivy, it should not be planted under a sycamore tree. 

Coneflower

Close up of beautiful purple cone flowers (echinacea) with phloxes in the background

Coneflowers thrive in hardiness zones 3 through 9, right alongside sycamore trees. These herbaceous perennials bloom in summer and fall, producing pink or white flowers that resemble daisies.

Growing between 2 and 5 feet, coneflowers fit the right size to be planted under a sycamore tree. Unfortunately, they will not thrive.

Coneflowers prefer to be in full sun and will struggle in the shade cast by large sycamore trees. If the flowers are left on the plant throughout winter, they can become somewhat invasive and spread rapidly as well.

Peonies

It’s hard to beat peonies when it comes to flower size. They are so large that they can sometimes fall over under their own weight!

According to the University of Wisconsin-Madison, peonies will grow to about 3 feet tall and typically bloom in late spring.

Despite their beautiful flowers and easy maintenance, peonies will not thrive under a sycamore tree. Peonies do best in full sun and will struggle if they have to compete for water and nutrients.

Peonies are best planted on their own or with low-maintenance neighbors that will not outcompete them for resources.

Geraniums

Geraniums are popular flowers grown in hanging baskets and flower beds. Many different cultivars will produce flowers ranging from reds and pinks to blues and purples.

These spectacular flowers usually bloom in early summer and will last until the first hard frost. You can expect them to thrive in a flower bed or pot, but they will struggle under a sycamore tree.

Geraniums prefer full sun, making them a poor companion to a sycamore tree. Geraniums that can sneak 3 or 4 hours of sunlight under a sycamore may survive, but they will not bloom as well as they would if placed in full sun.

Delphiniums

The striking color and shape of delphinium flowers make them a favorite of many gardeners. These tall stalks produce brilliant blues, whites, and purples in the summer. If you cut the flowers immediately, delphinium may bloom again in the fall.

Delphiniums are perennials but they are short-lived, often needing to be replaced after just 2 or 3 years. They will grow between 2 and 6 feet, depending on growing conditions and the hybrid variety.

We wish delphinium would thrive under a sycamore tree, but it just won’t. They prefer full sun conditions and are heavy feeders, making planting under a sycamore tree difficult. 

Delphiniums may not do well under a sycamore tree, but they will thrive when planted in a perennial flower bed if placed near the back so as not to block other flowers from view.

Spider Flowers

Dark pink spider flower, closeup of a cleome blossom, blurry background

Spider flowers got their name from the long, thin stamens that resemble the legs of spiders. But don’t worry, this flower isn’t spooky or scary like spiders. The flowers are colorful, ranging from white, purple, and pink.

Also known as spider legs or grandfather’s whiskers, spider flowers bloom in early summer and will stick around until the first frost. 

Spider flowers do best in full sun conditions if you want the most bloom for your buck. In addition to their sun requirements, spider flowers are annuals, making them a high-maintenance plant that you would have to replant each year.

According to the University of Wisconsin-Madison, Spider flowers are also prickly and sticky, making it a bit of a hassle to take care of during the growing season as you will want to wear gloves.

The nice thing about spider flowers is that they attract so much wildlife. Bees, butterflies, beetles, hummingbirds, hummingbird moths, and even bats will pollinate the flowers!

Astilbe

A China native, Astilbe has an exotic appearance with whispy pink, white, or violet flowers and dark green foliage. Astilbes are perennials that will come back year after year.

There are plenty of positive attributes of astilbe. They can tolerate partial shade, they are non-invasive, and their flowers remain attractive all winter long.

Astilbes are also easy to take care of, requiring little water or care. Depending on the variety, they may be as small as 1 foot tall or as large as 6 feet tall.

So, what makes them a bad candidate for planting under a sycamore tree?

The only downside to astilbe is that it is a heavy feeder. This means it will compete against your sycamore tree for nutrients. 

Vinca

Also known as periwinkle, vinca has attractive foliage and flowers. The flowers vary in color depending on the cultivar but can be red, pink, purple, blue, or yellow.

Vinca does best when planted in full sun, preferring at least 8 hours a day. The shade thrown by a sycamore tree is going to be too much for vincas to survive beneath.

Another downside to vinca is that they can be invasive. They are a creeping vine and can creep their way all over your flower bed, choking out other plants if you don’t keep a watchful eye out and prune when necessary.

Other than their sun requirements and invasiveness, vincas are low-maintenance plants that are used to surviving in dry conditions. These resilient plants do not require fertilizer and can get a bit leggy if given too much water.

Chrysanthemum

Chrysanthemums, also known as just mums, can be grown as perennials but they are more commonly grown as annuals in the regions where sycamore trees grow.

The BEST thing about mums is that they bring a burst of color in the fall when they bloom. Compared to the other plants around them that are slowing down, mums bring life and color back to the yard.

Mums come in a variety of colors and the flowers will attract butterflies. When grown as a perennial in warmer climates, mums will bloom from fall to spring.

Mums will not do well planted under a sycamore tree. These colorful flowers prefer full sun conditions and are considered heavy feeders that will compete with your sycamore for nutrients.

If you simply want a beautiful splash of color for a few weeks in the fall, annual mums can survive under a sycamore tree. However, they will not bloom as well and will not come back the following year.

Lupines

20068202 l

Lupines are wildflowers that produce interesting spires of colorful flowers and attractive foliage. They make a beautiful addition to the flower garden.

These astounding plants can be grown as annuals or perennials, depending on the cultivar and the climate where they are growing.

While lupines can grow in shade, they prefer full sun and you’ll get a better display of flowers if they’re placed in full sun. Lupines also prefer acidic soil and will struggle in alkaline soil. 

The soil PH can be a problem since sycamores can grow in both acidic and alkaline soils. If it is growing on alkaline soils, lupines will have a hard time adapting.

What Plants Can Live Under A Sycamore Tree?

Growing plants under trees is a tricky business. With sycamores, you add on a broader area of shade and throw a curveball with their huge leaves that can change the nutrient content of the soil.

What kind of plants can live under a sycamore tree? Anything planted under a sycamore tree should be shade tolerant, low maintenance, and adaptable to different soil conditions.

Despite these obstacles, you have a lot of options when it comes to planting under a sycamore tree. Some of the BEST plants that can live under a sycamore tree include the following:

  • Jasmine
  • Barrenwort
  • Azalea
  • Ferns
  • Brunnera
  • Solomon’s seal
  • Hellebores
  • Meadow rue

All of these plants are low-maintenance, shade tolerant, and adaptable. 

Just because these plants grow in shade doesn’t mean their flowers are dull! Most of these plants produce colorful flowers at different times of the year, making the space under your sycamore tree pop with eye-catching color.

You can read more about the best plants to grow under a sycamore tree here if you’d like!

How To Help Plants Thrive Under A Sycamore Tree

If you’ve chosen a plant to grow under your sycamore tree, it’s time to take a few steps to ensure it stays happy and healthy.

This fertilizer comes in a 5lb bag and is in granule form that can be spread around the dripline of your sycamore tree. This will help alleviate any competition between your landscape plant and sycamore tree.

  • Give plants enough water: Sycamore tree roots are shallow and will compete with landscape plants for water. Make sure you give your plants enough water, especially if they start showing signs of drought stress such as yellowing leaves or wilting.
  • Pick the right spot for your plant: Take a good look at the growing conditions of your chosen plant. If it requires deep shade, plant it in a spot that gets little sun. if it requires partial shade, try to find a spot that gets morning or afternoon sun.

Alternatives For Under A Sycamore Tree

Knowing which plants can and can’t grow under a sycamore is great if you’re willing to dedicate some time and effort to selecting the right plants.

If you’d rather not deal with it, there are other options for the space under your sycamore tree.

  • Plant grass: shade tolerant grass like Scotts Turf Builder Grass Seed Dense Shade Mix will sprout with as little as 3 hours of sunlight. It comes in a 3lb bag with the option of upgrading to a 7lb bag if necessary.
  • Mulch: Mulch looks just as good on its own when placed around a sycamore tree. It makes the area look landscaped without the trouble of taking care of flowers. Be sure to keep the mulch at least 6 inches away from the trunk.

That’s A Wrap!

Sycamore trees will catch the eye of any passerby and is sure to be the statement piece of your yard. They are fast-growing and capable of adapting to different conditions.

The space under a sycamore tree will be shady, making planting difficult. Any plant that requires full sun, is a heavy feeder or needs a lot of water will struggle under a sycamore tree.

Now, for a quick recap:

The 11 plants that shouldn’t be planted under a sycamore tree include:

  • Impatiens
  • English Ivy
  • Coneflower
  • Peonies
  • Geraniums
  • Delphinium
  • Spider flower
  • Astilbe
  • Vinca (periwinkle)
  • Mums
  • Lupines

Instead of these plants, opt for low-maintenance plants that are shade tolerant and adaptable to dry conditions. You certainly don’t want your landscape plants competing with your sycamore tree for resources!

References

Jiang, Z.-D., Owens, P. R., Ashworth, A. J., Fuentes, B. A., Thomas, A. L., Sauer, T. J., & Wang, Q.-B. (2021, October 27). Evaluating tree growth factors into species-specific functional soil maps for improved agroforestry system efficiency. Agroforestry Systems96, 479-490. https://link.springer.com/article/10.1007/s10457-021-00693-9

Lee, E. H., Andersen, C. P., Beedlow, P. A., Tingey, D. T., Koike, S., Dubois, J.-J., Kaylor, D., Novak, K., Rice, R. B., Neufeld, H. S., & Herrick, J. D. (2022). Ozone exposure-response relationships parametrized for sixteen tree species with varying sensitivity in the United States. Atmospheric Environment284. https://www.sciencedirect.com/science/article/abs/pii/S1352231022002564

Mackie-Dawson, L. A., Millard, P., & Proe, M. F. (1995, June 01). The effect of nitrogen supply on root growth and development in sycamore and Sitka spruce trees. Forestry: An International Journal of Forest Research68(2), 107-114. https://academic.oup.com/forestry/article-abstract/68/2/107/522278

Sena, K., Agouridis, C., Miller, J., & Barton, C. (2018, December 18). Spoil Type Influences Soil Genesis and Forest Development on an Appalachian Surface Coal Mine Ten Years after Placement. Forests9(12), 780. https://www.mdpi.com/1999-4907/9/12/780/htm

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