Geraniums are a popular garden staple, known for their vibrant blooms and easygoing nature.
They’re one of those plants that can flourish in containers, garden beds, and hanging baskets alike, adding a pop of color throughout the growing season.
But as the summer winds down and September rolls in, it’s time to start thinking about how to prune your geraniums to keep them healthy and thriving.
Pruning geraniums in September not only helps tidy up the plant but also encourages more growth and prepares them for the coming winter.
I’ve spent years experimenting with different pruning techniques, and through trial and error, I’ve learned how to keep my geraniums looking their best as the season transitions.
In this guide, I’ll walk you through how to prune geraniums in September and share some personal tips to ensure your plants stay strong and beautiful.
Why Prune Geraniums in September?
September is a key time for geraniums because it’s the moment when the plant starts winding down from its peak blooming season.
Pruning at this time can help rejuvenate the plant and encourage more blooms if you’re in a mild climate, or it can prepare the geranium for overwintering if you’re in an area that experiences frost.
When I first started growing geraniums, I didn’t always realize the importance of a good September prune.
I would leave my plants as they were, only to find them looking straggly and tired as fall progressed.
Now, I make pruning a routine task at this time of year, and it’s made a noticeable difference in how my geraniums look and perform.
Pruning in September also helps reduce the risk of disease by improving air circulation around the plant.
Geraniums can sometimes fall victim to fungal diseases like botrytis or mildew, especially if the plant is left to grow unchecked.
By thinning out the plant and removing any dead or damaged material, you give the remaining foliage space to breathe, reducing the chances of disease taking hold.
Gather Your Pruning Tools
Before you begin pruning, it’s important to gather the right tools.
Having sharp, clean pruning shears is essential for making clean cuts that heal quickly.
In my early gardening days, I made the mistake of using dull or dirty tools, and I noticed that my plants were slower to recover from pruning.
Now, I always clean my shears before and after each use to prevent the spread of disease and ensure smooth cuts.
For geraniums, you don’t need anything too heavy-duty—simple hand pruners or garden scissors will do the trick.
I also like to have a small container or garden bag nearby to collect the trimmings as I go.
Geranium foliage can be a bit sticky and messy, so it’s helpful to stay organized and keep your work area tidy.
Remove Dead and Yellowing Leaves First
The first step in pruning geraniums in September is to remove any dead or yellowing leaves.
By this point in the season, the plant will likely have some older leaves that have started to fade or dry out.
These leaves are no longer contributing to the plant’s overall health and can actually be a source of disease or pests if left on the plant.
In my garden, I always start by scanning the plant for any foliage that looks unhealthy or is starting to turn yellow.
Using my pruning shears, I snip these leaves off at the base of the stem, making sure to remove the entire leaf and not leave any stubs behind.
This not only cleans up the appearance of the plant but also helps redirect energy to the healthier parts of the plant.
Dead or damaged leaves can sometimes be hiding beneath the outer foliage, so be sure to take a good look around the base of the plant as well.
Removing these early will help give your geraniums a fresh start for the fall season.
Cut Back Leggy Growth
One of the main reasons to prune geraniums in September is to deal with any leggy growth that has developed over the summer.
As geraniums grow, they can sometimes become tall and spindly, with long stems that produce fewer leaves and flowers.
This is especially true if your plants are in containers or crowded garden beds where they’re competing for light.
In my experience, cutting back leggy stems encourages the plant to grow bushier and fuller.
I usually cut these stems back by about one-third to one-half of their current length, making the cuts just above a leaf node.
This encourages new growth from the point where you’ve cut, resulting in a more compact, bushy plant.
When cutting back leggy stems, don’t be afraid to be a little bold.
It can feel a bit drastic to remove so much growth, but geraniums are resilient and will bounce back with renewed vigor.
I’ve found that my plants actually respond better to a good prune, producing more flowers and healthier leaves in the weeks that follow.
Deadhead Spent Blooms
Deadheading—removing spent flowers—is another important step when pruning geraniums in September.
By this time, your geraniums may have several blooms that are past their prime and starting to wilt.
If left on the plant, these spent blooms can divert energy away from producing new flowers and cause the plant to look untidy.
When I deadhead my geraniums, I make sure to remove the entire flower stem, not just the faded petals.
I’ve seen some gardeners only pinch off the flower heads, but I’ve found that cutting the entire stem back to the next leaf node helps promote more flowering.
It also prevents the plant from putting energy into producing seeds, which can further drain its resources.
In areas with mild climates where frost is not a concern, deadheading can encourage your geraniums to keep blooming well into the fall.
In my own garden, I’ve had geraniums produce a second flush of flowers in late September and even October after a good deadheading session.
Thin Out Crowded Stems
Thinning out crowded stems is an important step to ensure your geraniums stay healthy.
Geraniums that are too dense can suffer from poor air circulation, leading to fungal diseases and pest issues.
By thinning the plant, you allow light and air to reach the inner parts of the plant, which helps keep it healthy and vibrant.
When I thin out my geraniums, I focus on removing any stems that are crossing or rubbing against each other, as these can cause wounds and invite disease.
I also take out any weak or spindly growth that isn’t contributing to the plant’s overall shape or structure.
After thinning, the plant should look more open, with space between the remaining stems and leaves.
It’s important not to overdo it—geraniums don’t need to be thinned too aggressively.
I usually aim to remove about 10-15% of the growth, just enough to improve airflow without drastically changing the plant’s appearance.
Shape the Plant for a Tidy Look
While geraniums are naturally somewhat loose and sprawling, you can shape them to create a more controlled, tidy appearance.
In September, I like to give my geraniums a light shaping to keep them looking neat and balanced.
This is especially helpful if your geraniums are in containers or placed in a formal garden bed where a more structured look is desired.
To shape your geraniums, simply prune any stems that are growing out of the desired shape.
I usually trim back stems that are growing too far outward or upward, creating a more rounded or compact form.
It’s important to make cuts just above a leaf node or bud to encourage new growth in the direction you want the plant to go.
Shaping your geraniums in September will help them maintain a neat, attractive appearance as they head into the fall, and it also makes them easier to manage when it comes time to overwinter them.
Prepare for Overwintering
If you live in an area where frost is common, September is a good time to start thinking about how to overwinter your geraniums.
Geraniums are frost-sensitive, so they need protection if you want to keep them alive through the winter.
In my garden, I either bring my potted geraniums indoors or prepare my garden-grown geraniums for a dormancy period in a cool, frost-free space like a garage or basement.
After pruning in September, I stop fertilizing and reduce watering to help the plant transition into dormancy.
If you’re bringing your geraniums inside, cut them back by about one-third to make them more manageable and less likely to attract pests indoors.
For garden-grown geraniums, I’ve found that adding a layer of mulch around the base of the plant after pruning can help protect the roots from freezing temperatures.
In milder climates, geraniums may survive outdoors, but in colder zones, they need to be dug up and stored in a cool, dry place until spring.
Monitor for Pests and Diseases
After pruning your geraniums, it’s a good idea to keep an eye on them for any signs of pests or disease.
Geraniums can be prone to problems like aphids, spider mites, and fungal diseases, especially if the weather turns damp in the fall.
I always inspect my plants carefully after pruning, looking for any signs of damage or discoloration on the remaining leaves and stems.
If I notice any pests, I treat them immediately with a strong spray of water or insecticidal soap.
For fungal issues, I remove any affected leaves and ensure that the plant is getting good air circulation.
By staying vigilant and addressing issues early, you can keep your geraniums healthy and looking their best well into the fall.
Water Wisely After Pruning
After pruning your geraniums, it’s important to adjust your watering routine.
Because you’ve removed a significant amount of foliage, the plant won’t need as much water as it did during its peak growing season.
In September, I reduce the frequency of watering, making sure the soil stays slightly moist but never soggy.
Geraniums don’t like to sit in water, so it’s important to let the top inch of soil dry out between waterings.
Overwatering can lead to root rot, especially as the temperatures start to cool down.
For container-grown geraniums, be sure to check that the drainage holes are clear and that excess water can escape.
Good drainage is essential for keeping your plants healthy after pruning.
Fertilize Sparingly
While geraniums benefit from regular fertilization during the growing season, it’s best to scale back on feeding after pruning in September.
At this point in the year, the plant is preparing to slow down its growth as it transitions into fall and winter.
I usually stop fertilizing my geraniums altogether after pruning, as I’ve found that encouraging too much new growth in the fall can leave the plant more vulnerable to frost damage.
If you’re in a mild climate where your geraniums will continue blooming into the fall, you can give them a light feeding with a balanced fertilizer, but it’s not strictly necessary.
Final Thoughts
Pruning geraniums in September is a crucial step in keeping them healthy, vibrant, and ready for the next growing season.
By removing dead leaves, cutting back leggy growth, and shaping the plant, you’ll help your geraniums stay tidy and strong through the fall.
Whether you’re preparing your plants for overwintering or extending their bloom time in a mild climate, taking the time to prune properly will reward you with healthier, fuller plants next year.
From my own experience, I’ve found that September pruning not only improves the appearance of my geraniums but also helps prevent disease and pest issues.
With a few simple steps, you can give your plants the care they need to thrive year after year.
So grab your pruning shears and get started—your geraniums will thank you for it!