In August, keep peonies' healthy green foliage intact, water deeply during prolonged dry weather, remove clearly diseased leaves, control weeds carefully, and deadhead any remaining spent flowers. Avoid cutting healthy foliage back too early or stressing the plant with excessive pruning. For herbaceous peonies, the main cutback should wait until fall after the foliage naturally declines or a hard freeze occurs.
5 August Peony Tasks and 2 Mistakes That Can Affect Next Year's Blooms
Peonies may be finished flowering by August, but that doesn't mean their work for the season is over.
The spectacular blooms may have disappeared weeks ago, yet the green foliage is still actively supporting the plant. During late summer, peonies continue producing energy that helps them maintain their underground structures and prepare for the next growing season.
That's why August is a surprisingly important month for peony care.
Many gardeners make the mistake of looking at a peony after flowering and thinking it can simply be cut to the ground. Others stop watering once the flowers disappear or ignore foliage diseases until autumn.
Both approaches can create unnecessary problems.
The good news is that August peony care is relatively simple. You don't need an elaborate routine or constant pruning. Instead, focus on keeping the plant healthy, protecting its foliage, and avoiding the two major mistakes that can interfere with next year's performance.
Here are five August peony tasks worth doing now.
Why August Matters for Peonies
Herbaceous peonies have a relatively short flowering period, but their growing season continues long after the flowers fade.
The green leaves remain important because they continue photosynthesizing. Iowa State University Extension recommends watering peonies during dry weather and leaving the foliage until fall, when it can be cut back after a hard freeze.
Late summer is also when several peony foliage diseases can become noticeable.
Penn State Extension reports that peony leaf blotch, Botrytis blight, and powdery mildew can appear as the season progresses. The recommendation is to remove heavily diseased portions while leaving as much healthy green foliage as possible so the plant can continue photosynthesizing.
So August isn't about aggressive pruning.
It's about protecting the healthy growth you already have.
1. Keep Healthy Peony Foliage in Place
This is arguably the most important August task.
Don't cut healthy peony foliage to the ground simply because flowering has finished.
The green leaves are still producing energy for the plant.
If you remove them too early, you reduce the amount of healthy foliage available for photosynthesis during the rest of the growing season.
Iowa State University Extension specifically recommends waiting until fall for the major cutback. It advises cutting the foliage at ground level after a hard freeze and removing the plant debris.
Penn State's August guidance makes the same basic point: remove heavily diseased portions when necessary, but leave as much healthy green foliage standing as possible through the end of summer.
That means your August peony may look less tidy than it did during flowering.
That's perfectly fine.
The leaves are doing useful work.
What Healthy Peony Foliage Should Look Like
Healthy foliage should generally remain green and functional.
A few imperfect leaves aren't necessarily a reason to reach for the pruners.
Look for widespread or worsening symptoms instead of reacting to every small blemish.
The goal is to preserve healthy foliage while removing material that is genuinely dead or diseased.
2. Water Peonies During Prolonged Dry Weather
August heat can be tough on perennial plants.
If your area experiences a prolonged dry spell, don't assume peonies no longer need water because they have finished flowering.
Iowa State University Extension recommends watering peonies during dry weather and notes that water is particularly important during bud formation and flowering.
While the flowering period may be over by August, severe summer drought can still stress the plant.
A good approach is to check the soil rather than watering automatically every day.
If the soil is becoming significantly dry, water thoroughly enough to moisten the root zone.
Avoid frequent, shallow watering when a deeper soaking is appropriate.
At the same time, don't turn the planting bed into a permanently wet environment. Peonies perform best in well-drained soil.
How to Water Peonies in August
A simple routine is:
- Check the soil around the plant.
- Water during prolonged dry conditions.
- Apply water deeply enough to reach the root zone.
- Allow excess water to drain away.
- Avoid repeatedly wetting the foliage if possible.
A moderate layer of mulch can also help reduce evaporation and stabilize soil moisture.
Keep mulch away from the crown instead of piling it directly over the base of the plant.
3. Remove Diseased Foliage
August is a good time to inspect peonies carefully for disease.
Penn State Extension notes that late summer can bring several common peony diseases, including:
- Peony leaf blotch
- Botrytis blight
- Powdery mildew
Leaf blotch can produce reddish-purple to brown lesions on leaves and red or purple streaks on stems. Botrytis can cause irregular brown or blackish spots, while powdery mildew produces a white coating on foliage.
You don't need to remove an entire plant because of a few damaged leaves.
Instead, identify the most affected portions and remove them carefully.
Penn State recommends leaving healthy green foliage in place while removing heavily diseased sections. It also recommends disinfecting pruning tools regularly to reduce the chance of spreading fungal spores.
Why Disease Cleanup Matters
Some peony diseases can overwinter in plant debris.
That means late-season sanitation can affect disease pressure in the following year.
Penn State recommends removing diseased foliage and plant debris rather than allowing infected material to remain in the growing area.
This is particularly important if your peonies have had recurring disease problems.
Don't simply hide infected leaves under mulch.
Remove them from the garden appropriately.
4. Keep Weeds Under Control
August weeds can quickly become established around mature peonies.
They compete for:
- Water
- Nutrients
- Growing space
- Light
Removing them helps keep the planting area healthier and easier to monitor.
However, be careful with deep cultivation.
Peonies have established underground roots, and aggressive digging close to the plant can cause unnecessary damage.
Iowa State recommends cultivating shallowly around peonies—no deeper than about 2 to 3 inches—and taking extra care near the crown.
For many home gardens, hand-pulling young weeds is safer than aggressively digging around the plant.
Mulch Can Help
A suitable layer of organic mulch can suppress weeds and help maintain more consistent soil moisture.
Just don't pile mulch directly over the peony crown.
A thick, constantly wet layer around the crown can create conditions you don't want.
5. Deadhead Any Remaining Spent Flowers
Most peonies have finished flowering well before August, but if there are remaining spent flowers or seed pods, remove them.
Iowa State recommends removing flowers as they wither because allowing fruits to develop diverts some of the plant's energy.
Deadheading is simple.
Use clean, sharp pruners and remove the faded flower and its stem while preserving the healthy foliage below.
You don't need to perform aggressive pruning.
Just remove what's finished.
If seed collection is your goal, you can allow selected seed pods to mature. But if your primary goal is maintaining an established garden peony for strong future flowering, there's usually little reason to let every flower develop fruit.
The 2 August Mistakes That Can Affect Next Year's Blooms
The five tasks above are straightforward.
The bigger challenge is avoiding mistakes.
Two in particular deserve your attention.
Mistake 1: Cutting Healthy Peony Foliage Too Early
This is one of the most common late-summer mistakes.
A peony finishes flowering, begins looking less attractive, and suddenly the gardener decides it's time to cut the entire plant down.
Don't do that while the foliage is still healthy and green.
Iowa State recommends waiting until after a hard freeze in fall before cutting herbaceous peony foliage to ground level.
Penn State's August guidance similarly recommends keeping healthy foliage in place so the plant can continue photosynthesizing.
Cutting too early removes valuable foliage before the plant has completed its seasonal growth cycle.
What to Do Instead
Leave healthy green foliage alone.
Remove only:
- Spent flowers
- Dead stems
- Severely diseased leaves
- Clearly damaged growth
Then wait until fall for the major cleanup.
Mistake 2: Ignoring Diseased Leaves Until Winter
The opposite mistake is leaving severely diseased foliage untouched simply because it's still summer.
If a peony has significant leaf blotch, Botrytis, or another disease problem, allowing heavily infected material to remain can increase the amount of disease material present later.
Penn State recommends removing heavily diseased portions during late summer while preserving healthy foliage.
Then, during fall cleanup, remove the remaining above-ground foliage once it naturally dies back.
This gives you a better balance:
Protect healthy foliage. Remove diseased foliage.
Should You Fertilize Peonies in August?
Fertilizing isn't necessarily required simply because August has arrived.
Peonies can grow successfully for many years in suitable soil without excessive feeding.
Iowa State's garden peony guidance recommends fertilizing in early spring and again immediately after flowering when fertilization is appropriate. It also warns that too much nitrogen can encourage foliage rather than flowers.
If you already fertilized after flowering, don't automatically add another heavy application in August.
More fertilizer isn't always better.
If your soil has a known nutrient deficiency, a soil test can provide more useful information than guessing.
Do Peonies Need Support?
If your peonies tend to flop, support is best installed before the heavy flower heads develop.
By August, adding support is mainly about stabilizing plants that still need help rather than trying to reshape them.
Penn State notes that herbaceous plants with heavy flowers, including peonies, can require support to keep stems upright.
For next year's blooms, consider installing grow-through supports early in spring before the stems become large.
That way the foliage and flowers can grow through the support naturally.
What About Ants on Peonies?
If you're still seeing ants around your peonies, there's generally no reason to panic.
Peony buds produce sweet nectar that attracts ants.
Penn State Extension explains that ants are attracted to nectar produced by the plant and do not need to be present for peony flowers to open.
So ants on peonies aren't automatically a pest problem.
You don't need to spray insecticide simply because you see ants around the plant.
When Should You Cut Peonies Back?
For herbaceous peonies, the major cutback should take place in fall.
Wait until:
- The foliage has naturally died back, or
- A hard freeze has killed the above-ground growth.
Then cut the stems close to the soil line and remove the plant debris.
Penn State's fall guidance recommends cutting peony stems to approximately 1–2 inches above the soil line and removing the foliage.
Iowa State similarly recommends cutting foliage at ground level after a hard freeze.
The exact calendar date will vary by climate.
Let the plant tell you when it's ready.
Don't Treat Every Peony the Same
Before doing major pruning, identify the type of peony you have.
Herbaceous Peonies
These have soft stems and die back to the ground in winter.
They can be cut back in fall after the foliage dies.
Tree Peonies
Tree peonies have woody stems that remain above ground.
They should not be cut to the ground like herbaceous peonies.
Intersectional or Itoh Peonies
These are hybrids between herbaceous and tree peonies.
Their stems generally die back in winter, and their care is broadly similar to herbaceous peonies, although specific cultivars can differ.
If you're unsure which type you own, identify the plant before making a major cut.
August Peony Care Checklist
Use this quick routine when inspecting your plants:
- Check the soil during dry weather.
- Water deeply when needed.
- Look for diseased leaves.
- Remove heavily diseased portions.
- Keep healthy green foliage intact.
- Pull weeds carefully.
- Remove remaining spent flowers.
- Check mulch depth.
- Avoid aggressive pruning.
- Plan fall cleanup.
A few minutes of inspection each week can help you catch problems early.
How to Prepare Peonies for Fall
As summer begins to fade, shift your attention toward fall cleanup.
Don't rush.
Healthy foliage can remain in place while it is still green and functioning.
Once the leaves naturally turn brown or a hard freeze kills the top growth, cut herbaceous peonies down and remove the debris.
If disease was present during the season, be especially careful about removing infected material from the garden.
Penn State notes that removing diseased plant debris can reduce the amount of disease inoculum available for the following season.
Frequently Asked Questions
Should I cut peonies back in August?
No, not if the foliage is healthy and green. Leave healthy foliage in place through the summer and wait until fall for the major cutback.
What should I do to peonies in August?
Water during prolonged dry periods, inspect for disease, remove heavily diseased foliage, control weeds, deadhead remaining spent flowers, and leave healthy green foliage intact.
Should I remove peony leaves after flowering?
Healthy leaves should remain after flowering. They continue photosynthesizing and supporting the plant. Remove leaves that are dead or seriously diseased.
Can I deadhead peonies in August?
Yes, if there are still spent flowers or seed pods. Remove the faded flower and stem while preserving healthy foliage.
When should I cut peonies down for winter?
For herbaceous peonies, wait until the foliage has naturally died back or a hard freeze has killed the above-ground growth. Then cut the stems close to the ground and remove the debris.
Why are my peony leaves turning brown in August?
Possible causes include natural seasonal decline, drought stress, or disease. Peony leaf blotch, Botrytis blight, and powdery mildew can all appear during late summer.
Should I water peonies after they finish blooming?
Yes. Peonies still need adequate moisture during dry periods after flowering. Avoid allowing the soil to remain excessively dry for extended periods.
Should I fertilize peonies in August?
Not automatically. Iowa State recommends fertilization in early spring and immediately after flowering when needed, and warns that excessive nitrogen can encourage foliage rather than flowers.
Should I remove diseased peony leaves?
Yes. Remove heavily diseased portions while preserving healthy green foliage. Clean your pruning tools between cuts when disease is present.
Do ants harm peonies?
Generally, no. Ants are attracted to nectar produced by peony buds and flowers. Their presence is not a reason to spray insecticide.
Final Thoughts
August is not the month to abandon your peonies simply because their flowers have disappeared.
It's the month to protect the healthy growth that remains.
Keep the foliage green and intact for as long as possible. Water during.
