8 Plants You Should Not Grow Under Your Ash Tree

Ash trees can be beautiful additions to your yard, providing colorful foliage in the spring, summer, and fall. Ash trees also provide a great deal of shade. If you are looking for plants to plant under your ash tree, you might not be sure where to start. This guide is here to help!

You shouldn’t grow plants such as mums, lavender, lamb’s ear, canna lilies, lantana, milkweed, pansies and bee balm under your ash tree. These plants are either invasive or require significant amounts of sunlight, which would be difficult to get under the shade cast by the canopy of an ash tree.

As long as you pay attention to the environment under your ash tree and the needs of each plant you choose, you can have a spread of foliage at the base of your ash tree, just as beautiful as the tree’s canopy. Read on for all the info you need to make the best choices when purchasing plants for the ground underneath your ash tree!

Why Certain Plants Can’t Grow Well Under Your Ash Tree

Ultimately, some plants have more needs than others and will often lead to a competition for resources, especially when at the base of an ash tree near their roots.

Ash Trees Cast Shade Over Sun Loving Plants

The base of your ash tree is most likely a very shady place. In fact, it is probably an area of your yard that is always shady except in the winter when the leaves of your ash tree are gone.

This means this spot is the perfect place for perennial shade plants, which require little sunlight (and even die or grow poorly in lots of light) and which return year after year.

There are several plants that, while they might appear to be the type of plant that thrives in the shade, are sun-loving plants. These are poor choices for the base of your ash tree.

Another thing to consider about light is whether the plants you have chosen will go dormant in the winter or will continue to grow. If you choose annual plants, they will most likely die in the fall or winter for good, and you will have to plant entirely new plants the following spring or fall, depending on which planting season you choose.

Most plants are planted in spring, but some, like autumn mums, for example, are planted in the fall.

If you choose perennials that are still thriving in the cold months, make sure they can tolerate both the shady seasons of spring, summer, and fall, when the ash tree has leaves on its branches, as well as winter when the leaves have fallen and the branches are bare.

Ash trees make wonderful shade trees, and you can learn more about why in our other post!

Ash Tree’s Will Compete For Water With Other Plants

If you choose plants that require a lot of water, but you are not prepared to be diligent in watering them, you are probably setting your plants up for failure.

No matter what type of plant you choose, pay attention to the amount of watering that is required and consider whether you can provide that much water to the ground under your ash tree.

Use A Sprinkler System For Plants Under Your Ash Tree

If you want to supply extra water, there are several ways to do that. You can choose to install a sprinkler system.

This is the most complicated and likely the most expensive method, as it requires digging trenches in your yard and installing the tubing and parts to water your lawn.

You also have to install a control unit that you can program to operate the sprinklers. 

If you already have one of these systems, great! Now check that it adequately waters the ground under your ash tree. Many sprinkler systems will water the grass of the lawn, so that does not always mean that they reach the flower beds, roots of trees, or other areas of the yards. Make sure it’s slow moving and gets a nice deep water so it reaches the bottom of all roots.

If your system does not reach and you do not want to make modifications to it, you will need to rely on one of these other systems.

If you’d like to learn more, take a look at our guide on the specifics of how much water ash trees need!

Watering Without A Sprinkler System: How To Make It Easier

If you do not have a sprinkler system, or yours does not provide enough water to the base of your ash tree, you still have a number of options.

The most simple is perhaps to stand there every day or so spraying the ground around your ash tree with a garden hose. Many people choose this method and even find it a relaxing part of their day.

If you would rather automate the system, you can use a standard garden hose attached to a sprinkler head. You can also use a sprinkler hose, which is a two-in-one hose that acts like a sprinkler.

This Swan Element Sprinkler Hose can be turned in one direction to spray the water like a sprinkler, and you can also use it as a soaker hose that lies on the ground, providing water without spraying it into the air.

To get your watering system automated so that basically nothing is required from you at all, set the system up with an automatic timer. This Orbit Single-Outlet Hose Watering Timer can be set so that the water turns on and off whenever you want. It even has a rain delay function that can help you save water by not watering when it has recently rained.

I can’t say this enough, water DEEPLY so you reach all the roots!

8 Plants To Avoid Planting Under Your Ash Tree

These general guidelines can help you make some good choices about what to plant under your ash tree and take better care of your plants once you decide what to plant.

You can apply these to any plant you consider along your journey to add colorful blooms, vibrant greenery, or ground cover to the area around the base of your ash tree.

Here are a few plants you should avoid, as they are not good options for the base of your ash tree.

Mums

Mums are beautiful flowers, especially in the fall, so it might be tempting to plant some under your ash tree, hoping that their bright autumnal colors will complement the yellow fall leaves of your ash tree. There are also varieties of mums that bloom in the spring.

This versatile flower seems to have something for everyone, potentially making it a choice for some colorful blooms under your ash tree. 

However, mums are very unlikely to survive under an ash tree for longer than those first few weeks of bloom right after you have planted them if you planted them in the fall. If you planted them in the spring, they probably will not even make it to their first bloom.

Why are mums such an awful choice for under your ash tree? They will not do well for one main reason: mums thrive in lots of sunlight. Planted in the shade, like under the full canopy of an ash tree, mums will not receive enough light to flourish and will probably even parish.

If you want the color of mums, or the festivity of their fall blooms, under your ash tree, your best bet is to use annual mums that are planted in containers. These blooms will survive the season under your ash tree, but you will need to either move them or say goodbye after a few weeks. 

Lavender

Lavender is a wild-looking but lovely plant that produces a famous scent. It does not require much care, and it thrives in dry conditions. It seems like it might work well as the type of plant you could plant underneath an ash tree and enjoy with little effort. But, unfortunately, that is not the case.

Lavender is another plant to avoid under your ash tree, in part because of its sunlight requirements.

Lavender needs full sun, all day to thrive, and it will receive little to no sun under your ash tree, except maybe in winter. According to Purdue University, lavender goes dormant in the winter, so it will be too late by then to give it the sunshine it needs. 

Another reason that lavender is a poor choice for planting under your ash tree is that lavender likes very dry soil, but your ash tree probably does not. And planting a plant like lavender under your tree, that cannot tolerate a lot of watering, will prevent you from planting much of anything else there, as most plants, especially those that thrive in full shade, need a lot of water.

Lamb’s Ear

Lamb’s ear is an interesting plant, given its common name because of the soft and fuzzy texture of its leaves, which resemble the ears of lambs. It has a soft color, too, of a pale green, and grows purple flowers. It might seem like an ideal choice for an interesting and pretty addition to the plants around your ash tree, but it is not.

The sunlight requirements of lamb’s ear make it unlikely to grow in the shade of your ash tree. So while this evergreen plant with leaves all year round is a tempting prospect for gardeners who want something that will not turn brown and die in the winter, lamb’s ear is best left to other, sunnier parts of your yard, not under your ash tree.

Also, lamb’s ear is an intensely spreading plant.

Planted in a flower bed, it can serve almost like ground cover, filling in the gaps between other plants. But under an ash tree, unless containers are built, lamb’s ear would spread enough as it would have to be regularly pruned, so it takes away from the effortless nature of some other types of plants better suited for under an ash tree.

Canna Lilies

Under a tree with bright green leaves, it might seem like a good idea to plant some brightly colored flowers with tall stalks to give color and depth to the base of your ash tree.

Canna lilies are a popular and common flower that comes in many colors, from yellow and orange to bright pinks and reds. But these flowers will not provide those vibrant blooms under your ash tree.

Canna lilies need full sun, so they will not receive enough light under your ash tree to thrive and bloom. If you want to plant them elsewhere, choose a flower bed without shade or even the side of your house that gets the most sunlight. 

Additionally, canna lilies are planted as bulbs, so it might be difficult to find a spot under your ash tree that isn’t already taken up by the roots of the tree.

According to the State of Colorado’s cooperative extension program, you can estimate the size of the root system of your tree by looking at its canopy; the root systems will be about two or three times the size of the spread of the tree’s branches.

Roots that expand that much may have created an inhospitable environment for canna lily bulbs. It’s best to avoid this flower for the area under your ash tree.

Lantana

Lantana is a flowering plant that thrives in heat and sunlight, which makes it a favorite for gardeners who live in hot, dry climates. But these favored conditions of the lantana make it a bad choice for under an ash tree with a shady canopy. 

Another feature of lantana that makes it an awful choice for under your ash tree is that lantana can be invasive, meaning that it can take over the areas where other plants are planted and end them.

Lantana is best used as a container plant or in a structured flower bed where it can’t escape to wreak havoc on other plants and other areas of your yard.

Milkweed

Do you love butterflies? If so, milkweed might be an interesting option for you, as the plant attracts butterflies. It is particularly well-known for being a favorite of the iconic orange and black monarch butterfly, which is also known as the milkweed butterfly.

According to the University of Arizona, milkweed is of integral importance to monarch butterflies because it is where they lay their eggs, and the caterpillars eat the milkweed before spinning their cocoons.

Milkweed needs full sun, so it will not grow well under your ash tree. So if you want to help all those beautiful monarch butterflies, plant the milkweed somewhere else.

Another major reason not to plant milkweed at the base of your ash tree is that the insecticides that are required to treat ash trees for emerald ash borer infestation are dangerous to the butterflies themselves.

So, even if milkweed could grow well under your ash tree, you would pose a risk to the butterflies that want to eat the milkweed, as the flowers would likely have been inadvertently treated with an insecticide dangerous to the insects.

Pansies

If you want to plant something that will bloom in the wintertime when most everything else seems dead, pansies are a great option.

But, while they can tolerate some shade, pansies do best with a lot of sunlight, meaning that, once again, the canopy of your ash tree causes some problems for growing these winter flowers.

Also, according to Utah State University, pansies are sensitive to weeds, which can keep them from growing properly because they steal their water and nutrients. If you want something low-maintenance under your ash tree, these flowers are not the best choice. 

Bee Balm

As its name suggests, bee balm is beloved by bees, as well as by other insects and wildlife, like hummingbirds. But, like the others on our list, it is not a great choice for planting under trees because it likes full sun.

Bee balm is also an invasive spreader, meaning that it will quickly take over the surrounding area, which can harm other plants. It is also susceptible to mildew, which can not only kill the bee balm but might be a problem for other plants, including the ash tree.

Red Flags When Choosing Plants For The Base Of Your Ash Tree

There are some general things you can look out for aside from just sunlight and watering requirements when thinking about what to plant under your ash tree. 

First, there are some dangers particular to ash trees to look out for, like cotton root rot, also known as Texas root rot.

This rot, caused by a fungus, can spread to ash trees from other plants, so you don’t want to plant something under your ash tree that is particularly susceptible to cotton root rot. According to the USDA, this includes different types of plants including roses, so that is one type of plant to avoid, no matter the sunlight requirement. 

You should also look out for plants that might be harmful to plants you have already placed around your ash tree. If you have planted some shade perennial plants, for example, make sure you do not plant invasive species or plants that will overpower the others.

Last, be sure to space your plants appropriately so that each one can get the required nutrients and water that it needs.

If you’re considering planting an ash tree in the future, I highly recommend taking a peak at our guide on the best time to plant ash trees – it’s a good one!

That’s A Wrap!

Now you are ready to make some great choices for plants to plant under your ash tree. While this list is a what-not-to-plant, there are a lot of great options out there to suit most gardeners who want to add some foliage or even flowers to the base of an ash tree. 

Just remember to keep an eye out for not only the sunlight requirements but also the depth at which plants must be planted, the amount of water they need, and their general compatibility with not only your ash tree but also other plants that might be planted around or near it.

Happy planting!

References

Taylor, Subhashni, and Lalit Kumar, Nick Reid, and Darren J. Kriticos (2012). “Climate Change and the Potential Distribution of an Invasive Shrub, Lantana camara L.” PLOS ONE, https://doi.org/10.1371/journal.pone.0035565. 

Herms, D. A., McCullough, D. G., Smitley, D. R., Sadof, C. S., Williamson, R. C., & Nixon, P. L. (2009). Insecticide options for protecting ash trees from emerald ash borer. North central IPM center bulletin, 12.