13 Plants You Should Never Plant with Peonies

After years of caring for my garden beds I’ve learned what works with peonies and what makes them unhappy. In this case the wrong companions make a big difference.

So I’m going to give you some insights about what plants don’t work with peonies and why.

Understanding Peonies

Peonies can be particular about both their growing conditions and what they’re grown with. To get those beautiful flowers you still have to do some careful planning.

Just last spring I had a plan for getting peonies to grow but ruined it by crowding some new varieties with aggressive spreaders. After waiting years for my peonies and then got basically nothing.

Modern varieties of Peonies need proper spacing, the right sunlight and neighbors they won’t fight with. So what you plant them with will play a big part in how successful they are.

Why Companion Planting Matters for Peonies

• Peonies have shallow roots and hate fighting for nutrients
• They need excellent air flow to stop diseases
• Most varieties need 6+ hours of direct sunlight to flower properly
• They can be affected by specific fungal problems which can spread
• Once established they don’t like being disturbed or moved
• They can live over 50 years in the right conditions (no pressure!)

Plants NOT to Plant With Peonies

1. Aggressive Spreading Perennials

The mint family, including catmint and lemon balm, grows runners underground that go everywhere. One small plant will takeover and starve peonies of nutrients and space.

Why they’re problematic:

• Overtake the area peonies roots grow
• Take nutrients from the soil
• Make too much competition for water
• Once they’re established it’s almost impossible to remove mint without disturbing the peonies

2. Large Trees and Shrubs

I planted a small maple tree 15 feet away from my peonies thinking that was more than enough room. Five years later its roots and the shade it made had caused major problems. The peonies has far fewer blooms each year until they just gave up.

Problems with trees near peonies:

• The roots steal nutrients and water
• The shade makes any flowers bloom much less
• Leaf litter can have diseases in that affect peonies
• Falling branches can damage peonies

3. Tall Ornamental Grasses

The big roots of grasses will choke out the peonies. They look wonderful swaying in the breeze but their roots are aggressive under the ground.

What makes them incompatible:

• Aggressive roots steal everything from peonies
• Makes too much shade when they’re fully grown
• Drops seeds that can then germinate in your bed of peonies
• Many need division every few years which upsets nearby peonies

4. Sunflowers

My neighbor asked me why her peonies failed to bloom after last year’s had been so successful. It turned out she had added some sunflowers to “fill the space” after her peonies had bloomed. Sunflowers have aggressive roots and take a lot of nutrients that leave nothing for the peonies to store for next year.

How sunflowers harm peonies:

• Take lots of nutrients from the soil
• Creates a lot of shade
• Drops seeds everywhere that fight with peonies the next season
• Attract pests that can jump to peonies

5. Deep Rooted Vegetables

Trying to create an edible or ornamental garden by putting tomatoes and potatoes near a border of peonies might seem like a brilliant idea at first but powdery mildew will spread from the vegetables to the peonies. And having to water the vegetables more can cause fungal issues with peonies.

Making it problematic:

• Different needs when it comes to water can stress the peonies
• Both are likely to get certain diseases
• When you harvest the vegetables it upsets the roots of the peonies
• Having to fertilize vegetables often can burn peony roots

6. Other Peony Varieties Too Close Together

I once had a friend who had planted 12 peony varieties all within a small space. Unsurprisingly they didn’t do well. That’s because peonies will fight with other peonies and no one wins. Each plant needs about 3 feet of dedicated space.

Getting the spacing wrong:

• Creates direct competition between plants that are both fairly demanding
• Reduces air flow which makes diseases more likely
• Makes it impossible to get to plants for maintenance
• Results in weaker stems and smaller flowers on all plants

7. Wisteria and Other Aggressive Vines

A wisteria and peony combination looks amazing but that’s up until the wisteria decides to take over. The vines make a lot of shade and grows hard so that the peonies never have a chance.

Getting the Details Right:

• Vines will strangle peony stems
• Create a lot of shade that stops flowering
• Underground runners upset peony roots
• Nearly impossible to remove once it’s established

8. Walnut Trees (or Any Tree with Juglone)

Planting peonies anywhere near walnut trees never going to work. Black walnuts produce juglone which is a natural substance that stops the growth of lots of plants, peonies being one of them.

How Juglone Affects Peonies:

• Stops the growth of plants and reduces how much they flower
• Causes yellow leaves
• Effects from walnut trees can can reach far
• Those effects can last in the soil even after the tree is gone

9. Plants Prone to Botrytis Blight

This is a common fungal disease and it moves easily between plants. Peonies will end up with black buds that never open if they catch it.

Tips to Make it Work:

• Don’t plant strawberries, tulips and roses too close to peonies
• All can be affected by botrytis blight
• Disease spreads quickly in the wet
• Can stay in the soil for years

10. Daylilies

Daylilies and peonies seem like great partners that bloom at the sort of times that would complement each other. But daylilies are aggressive and have roots that will take over and slowly choke out peonies.

Making it Work:

• Daylilies spread too quickly for peonies to compete
• They stop the air flowing
• They need to be divided regularly which upset peony roots
• Need different amounts of fertilizer

11. Bamboo (Even the “Clumping” Types)

Bamboo is terrible for peonies, even the “clumping” varieties. They eventually spread beyond their boundaries and get into the areas where peonies roots are growing.

Tips:

• Running bamboo can spread over 30 feet underground
• When you remove bamboo is usually damages any peony roots
• Creates too much shade
• Blocks the air flowing

12. Late Emerging Perennials

Don’t plant late emerging perennials like hostas with peonies. It’s common to plant hostas around peonies to ‘hide their bare legs’ after they’ve bloomed. But the problem is by the time hostas emerge the peony foliage is already growing and gets damaged.

What Creates Conflicts:

• Maintaining both becomes very difficult
• Different watering needs stresses the plants
• They don’t look great together

13. Aggressive Self Seeders

Be careful with putting self seeders near peonies. One garden I remember had allowed verbena free rein. Thousands of seedlings became a nightmare and they fought with peonies to the point of weakening them massively.

Plants to watch for:

• Verbena bonariensis
• California poppies
• Columbine
• Nigella
• Forget mennots

Good Companions for Your Peonies

So we’ve seen the problem plants – try these instead!

• Alliums (ornamental onions)
• Bearded iris
• Smaller varieties of salvia
• Heuchera (coral bells)
• Spring flowering bulbs (daffodils, small tulips)
• Catmint – kept at a distance

Tips for Successful Companion Planting

Start planning early but be smart about it. Focus your energy where it matters:

First year:

• Give peonies 3 feet of space
• Plant companions at least 18 to 24 inches away
• Focus on getting your peonies properly establishment before adding companions

Maintenance matters:

• Cut back peony foliage in the fall to stop disease from spreading
• Divide other plants regularly to maintain boundaries
• Look out for early signs of crowding or fighting

Smart selection:

• Choose companions that bloom at different times
• Select plants that have different types of root that grow to different depths
• Think about the texture of the leaves and how they look for year round appeal