Hostas are beloved for their lush foliage, low maintenance needs, and ability to brighten up shady corners of the garden.
They thrive in cool, moist environments and get along with many other plants.
But not all garden neighbors are created equal.
Some plants don’t just compete with hostas—they overwhelm them.
Whether it’s stealing moisture, hogging space, attracting pests, or loving way too much sun, the wrong companion can cause real trouble.
If your hostas aren’t thriving the way they should, their neighbors might be to blame.
To help you create a healthier, more harmonious shade garden, here are five specific plants you should avoid planting near hostas—and the reasons why they just don’t get along.
Black Walnut
If there’s one tree that causes more garden drama than any other, it’s the black walnut.
This towering beauty might look harmless, but beneath the surface, it’s hiding a toxic secret.
Black walnut trees produce a chemical called juglone, and hostas want nothing to do with it.
Juglone is released by the roots, leaves, and even the nuts of the tree.
It seeps into the soil and affects many other plants nearby—including hostas.
This chemical can disrupt your hostas’ ability to take up water and nutrients, leading to yellowing leaves, stunted growth, or even total collapse.
And the worst part?
Once juglone is in the soil, it’s hard to get rid of.
If you’re noticing that hostas near a black walnut tree just don’t look right—maybe they’re droopy, discolored, or struggling to grow—it’s not your watering routine.
It’s likely the tree’s allelopathic behavior at work.
The damage doesn’t happen overnight, either.
It can build up slowly over time, making it easy to miss until it’s too late.
The root system of a mature black walnut tree can stretch out as far as 50 to 80 feet in all directions.
That means even if your hostas aren’t right up against the trunk, they could still be affected.
So what can you do?
The easiest solution is to avoid planting hostas anywhere near a black walnut tree in the first place.
If you’ve already done it, try transplanting your hostas to a safer location with fresh soil—far from any juglone contamination.
It’s also worth noting that compost made from black walnut leaves, bark, or husks can carry juglone too.
So keep your compost pile free from any parts of the tree.
Bottom line?
Black walnut may be a stately tree, but for hostas, it’s a toxic neighbor.
Keep them far apart and your hostas will thank you with healthy leaves and better growth.
Ferns
Ferns and hostas might seem like natural partners.
They both love shady areas, they’re both foliage-focused, and they’re often sold together in garden centers.
But despite their similar preferences, ferns don’t always make the best neighbors for hostas.
Why?
Because many fern varieties are extremely competitive when it comes to space and moisture.
Ferns tend to form dense root systems that spread quickly just under the soil surface.
While they don’t seem aggressive on top, underground they can take over in a quiet but relentless way.
This can crowd out hostas before you even realize there’s a problem.
In a mixed bed, the ferns may absorb more than their fair share of water—especially in dry spells—leaving your hostas struggling to keep up.
Hostas like steady moisture, and once ferns dominate the soil, they often leave hostas looking droopy, thin, or tired.
And because ferns can grow tall and full, they sometimes block the limited sunlight that hostas do need to thrive.
If your hosta starts producing fewer leaves or shrinking over time, an overzealous fern might be the reason.
The issue gets worse when fast-spreading ferns like ostrich fern or lady fern are involved.
These can quickly take over a bed, sending runners in every direction and popping up between hosta clumps—making cleanup difficult without disturbing your hostas.
That doesn’t mean you can’t have both plants in the same garden.
But they do better when given their own space.
Try placing ferns in a separate bed or container where they can’t tangle roots with your hostas.
This gives each plant the conditions it needs to flourish without fighting for resources.
Ferns are beautiful, no doubt.
But when it comes to planting near hostas, they’re a bit like that neighbor who plays their music just a little too loud—you might like them, but you don’t want them living right next door.
Mint
Mint might be a favorite in the kitchen, but in the garden, it can be a nightmare—especially when planted near hostas.
It smells fresh and looks harmless, but make no mistake: mint is a ruthless spreader.
It grows fast, spreads through underground runners, and takes over whatever space it can find.
Once it sets its sights on your hostas, it can quickly crowd them out.
The problem with mint is how aggressively it grows.
It sends out long, creeping roots called stolons that run just beneath the soil surface.
Those roots don’t stop at bed edges or garden borders.
They’ll find their way into nearby hosta clumps and compete for space, water, and nutrients.
Before long, your once-neat hosta bed can become a tangled mess of mint shoots and smothered foliage.
Hostas need a little breathing room.
Their roots are shallow, and they like consistent moisture.
When mint moves in, it competes directly for that moisture, often drying out the soil faster than hostas can handle.
You may start to notice your hosta leaves drooping, fading in color, or producing fewer new shoots.
That’s a clear sign they’re being overrun.
And once mint is in the mix, removing it isn’t easy.
Even a tiny bit of root left behind can regrow quickly.
It’s a plant that takes the saying “give an inch, take a mile” to a whole new level.
If you absolutely love mint and want to grow it, keep it far from your hostas.
Plant it in a container or an area with deep edging that prevents spreading.
Better yet, sink a pot into the ground to contain the roots completely.
That way, you can enjoy your mojitos and mint tea without sacrificing your hostas.
In short, mint is best admired from a distance—well away from your shade garden stars.
Russian Sage
Russian Sage is a sun-loving, drought-tolerant perennial that thrives in dry, open spaces.
It’s a favorite for its tall, airy purple blooms and fragrant, silvery foliage.
But while it’s beautiful in the right setting, it’s a poor match for hostas—and planting the two side by side is a recipe for disappointment.
Why?
Because these two plants have completely different needs.
Hostas love shade and moist, rich soil.
Russian Sage, on the other hand, prefers full sun and dry, well-drained soil.
If you try to grow them in the same bed, one will almost always suffer—and spoiler alert, it’s probably going to be the hosta.
Hostas can’t take the dry, fast-draining conditions that Russian Sage loves.
When you water to keep your hostas happy, Russian Sage might struggle with the extra moisture.
But if you water less to keep the sage happy, your hostas will start to droop, wilt, or even burn.
It’s a classic case of mismatched roommates.
The sun requirements don’t line up either.
Russian Sage needs at least 6 to 8 hours of full sun daily to thrive.
That’s way more light than most hostas can tolerate.
Exposing hosta leaves to that much direct sunlight can lead to leaf scorch—brown edges, faded color, and stressed growth.
Even if you try to plant them where the shade and sun meet, the compromise often leaves both plants unhappy.
The hosta doesn’t get enough shade, and the sage doesn’t get enough sun.
It’s a lose-lose situation.
The best approach?
Give Russian Sage its own sunny corner of the yard—far from your hostas.
Pair it with other dry-soil lovers like lavender, yarrow, or ornamental grasses.
Let your hostas enjoy their shady, moist environment in peace.
Both plants can shine—but not when they’re planted together.
Barberry
Barberry might look like a harmless little shrub, especially with its bright red leaves and compact shape, but it’s one of the last things you want near your hostas.
It’s sharp, aggressive, and brings more problems than it’s worth—especially when it comes to keeping your garden peaceful and balanced.
Let’s start with the physical issue.
Barberry is covered in small, stiff thorns that make working around it difficult.
If your hostas are planted nearby, you’ll have a tough time trimming, watering, or weeding without getting scratched up.
But the real problem runs deeper.
Barberry is a dense, fast-growing shrub that can take over small areas of your garden surprisingly quickly.
It competes heavily for space, especially when grown close to the ground.
That thick, low-growing habit can block sunlight and airflow, which makes it harder for nearby hostas to thrive.
It doesn’t just crowd your hostas—it creates a dark, dry microclimate around their base.
And hostas, as we know, love moisture and room to breathe.
On top of that, barberry is known for changing the soil chemistry over time.
Invasive varieties can alter the natural balance of the soil, making it less suitable for moisture-loving shade plants like hostas.
But what’s worse?
Barberry attracts ticks.
Yes, the shrub has been linked to higher populations of ticks because it creates the perfect hiding place for them and their favorite hosts—like mice and deer.
That’s a big concern for gardeners who spend time working closely in flower beds.
Do you really want your relaxing shade garden to come with a side of pest problems?
Probably not.
If you’re looking for a colorful shrub to complement your garden, there are much friendlier options—like heuchera, hydrangea, or even dwarf fothergilla.
Save your hostas (and yourself) the trouble and plant barberry elsewhere—or better yet, skip it altogether.
Final Thoughts
Hostas are forgiving, but they still need the right environment to flourish.
Choosing the wrong neighbors can lead to stunted growth, yellowing leaves, or even a full garden takeover.
By avoiding plants like black walnut, bishop’s weed, mint, Russian sage, and barberry, you give your hostas the space and conditions they truly need.
A little planning goes a long way.
With the right plant partners, your hostas will thrive—and your garden will be healthier, easier to manage, and more beautiful for years to come.