How To Divide Chrysanthemums – Revitalize Your Garden And Multiply
Have you noticed your favorite fall flowers looking a bit thin in the middle lately? It is a common problem that every gardener faces as their perennials mature over the years.
By learning how to divide chrysanthemums, you can easily restore their health and fill your landscape with even more vibrant color. This simple technique is the best way to ensure your garden remains lush and productive season after season.
In this guide, I will walk you through the entire process, from choosing the right tools to caring for your new plant babies. You will be amazed at how easy it is to double your flower count without spending a dime!
Why You Should Learn How to Divide Chrysanthemums Regularly
Chrysanthemums, or “mums” as we often call them, are incredibly hardy and vigorous growers. However, their very strength can sometimes lead to their downfall if they are left to grow unchecked.
Over time, the center of the plant becomes woody and congested, which prevents nutrients and water from reaching the roots effectively. This often results in a “donut” shape where the middle is dead and the edges are blooming.
Learning how to divide chrysanthemums allows you to remove that old, unproductive wood and give the younger, more energetic shoots room to thrive. It is essentially a fountain of youth for your garden favorites.
Improving Plant Health and Airflow
When a mum gets too crowded, air cannot circulate through the foliage, which creates a breeding ground for mildew and fungus. Splitting the plant opens up the structure and keeps the leaves dry and healthy.
Better airflow means fewer pests like aphids or spider mites, which love to hide in the dense, stagnant interior of an overgrown perennial. Your plants will breathe easier and look much better for it.
Getting Free Plants for Your Landscape
One of the most exciting benefits of this process is the “free” plants you get at the end. Instead of buying new starts every year, you can turn one large mother plant into three or four healthy new ones.
You can use these new divisions to fill in empty spots in your borders or share them with neighbors and friends. It is one of the most rewarding ways to expand your garden on a budget.
The Best Time to Divide Your Mums
Timing is everything when it comes to successful perennial propagation, and mums are no exception. While you might see them for sale in the fall, that is actually not the best time to split them.
In my experience, the absolute best time to start is in the early spring, just as the new green shoots begin to emerge from the soil. This gives the roots an entire growing season to establish themselves.
If you wait until they are in full bloom in the autumn, the plant is putting all its energy into the flowers. Cutting them apart then can cause significant stress and may even lead to the plant failing to survive the winter.
Signs Your Plants Are Ready
Look for clumps that have been in the ground for at least two or three years. If the flower size has decreased or the center looks bare, it is definitely time to get your shovel ready.
I usually check my garden in late March or early April, depending on the local weather. When the new growth is about two to three inches tall, you have the perfect window for a successful division.
Weather Considerations
Try to pick a cloudy day or a late afternoon to perform your garden surgery. Intense, direct sunlight can dry out the exposed roots very quickly, leading to transplant shock.
A cool, drizzly day is actually a gardener’s best friend during this process. The moisture in the air helps keep the delicate root hairs hydrated while you work.
Essential Tools for a Smooth Division Process
You don’t need a shed full of expensive equipment to succeed, but having a few key items will make the job much easier. Clean tools are especially important to prevent the spread of soil-borne diseases.
I always recommend sanitizing your blades with a quick wipe of rubbing alcohol before you start. This simple step protects your plants from unwanted bacteria and fungi.
- A Sharp Spade: A flat-edged spade is perfect for slicing through tough root systems and lifting the heavy clumps.
- A Garden Knife: Sometimes called a “hori-hori,” this is great for making precise cuts in smaller, more delicate sections.
- Hand Trowel: Useful for digging the new holes and tucking the divisions into their new homes.
- Gardening Gloves: Mums can have slightly scratchy stems, so a good pair of gloves will keep your hands comfortable.
- A Watering Can: You will need to hydrate the plants immediately after they are moved.
Preparing Your Workspace
If you are dividing several plants, it helps to have a tarp or a large potting tray nearby. You can lift the clumps onto the tarp to keep your lawn clean while you work on the root balls.
I also like to have some fresh compost or well-rotted manure on hand. Adding a little organic matter to the new planting holes gives the young divisions a fantastic head start.
A Step-by-Step Guide to how to divide chrysanthemums
Now that you have your tools and the timing is right, it is time to get your hands in the dirt! Don’t be intimidated—mums are incredibly resilient and can handle a bit of tough love during the splitting process.
Follow these steps carefully, and you will have a 100% success rate. Remember, the goal is to keep as much of the healthy root system intact as possible while removing the old, woody bits.
- Water the plant: Give the mother plant a deep soak the day before you plan to divide it. Moist soil sticks to the roots better and makes the plant easier to lift.
- Dig around the perimeter: Use your spade to cut a circle around the plant, about six inches away from the outermost stems. This ensures you catch the majority of the root mass.
- Lift the clump: Slide your spade under the root ball and gently pry it upward. Work your way around the circle until the entire mass pops out of the ground.
- Shake off excess soil: Gently crumble away some of the dirt so you can see the root structure and the individual “crowns” or growing points.
- Slice the sections: Using your spade or knife, cut the clump into smaller sections. Each piece must have several healthy green shoots and a good cluster of roots.
- Discard the center: If the middle of the original plant is hard, woody, or lacks new growth, toss it into your compost pile. You only want the vigorous outer sections.
Handling the Roots with Care
While you want to be firm, try not to rip the roots apart with your bare hands. Clean cuts heal much faster than jagged tears, which reduces the risk of rot in the new divisions.
If the roots are very tightly intertwined, you can use two garden forks back-to-back to gently pry them apart. This “lever” method is very effective for large, old perennials that have become quite stubborn.
Determining the Size of Divisions
I usually aim for sections that are about the size of a grapefruit. This size is large enough to survive the move but small enough to grow rapidly into a full-sized bush by autumn.
If you make the divisions too small, they may take two years to reach a decent size. If they are too large, you might find yourself needing to divide them again much sooner than expected.
Replanting Your New Chrysanthemum Divisions
Once you have your healthy sections ready, you need to get them back into the ground as quickly as possible. Exposed roots are very sensitive to the wind and sun, so don’t let them sit out for too long.
Prepare your new planting sites by digging holes that are twice as wide as the root ball but no deeper. Mums hate being planted too deep; the crown should be level with the soil surface.
Knowing how to divide chrysanthemums also involves understanding their soil preferences. They love well-draining soil that is rich in organic matter, so mix in that compost we talked about earlier.
Spacing for Success
Give your new plants plenty of room to grow. I recommend spacing them about 18 to 24 inches apart. This might look a bit sparse at first, but they will fill in that gap surprisingly quickly.
Proper spacing ensures that each plant gets its fair share of sunlight and nutrients. It also maintains that vital airflow we discussed earlier, keeping your garden disease-free.
Firming and Initial Watering
After placing the division in the hole, fill it back in with soil and press down gently with your hands. You want to remove any large air pockets without compacting the dirt so much that the roots can’t move.
Water the area thoroughly right away. A deep soak helps the soil settle around the roots and signals to the plant that it is time to start growing in its new home.
Post-Division Care and Maintenance
Your work isn’t quite finished once the plants are in the ground. The first few weeks after division are the most critical for the long-term survival of your new mums.
Keep a close eye on the moisture levels. Because the root systems have been disturbed, they won’t be able to pull water from the soil as efficiently for a little while.
I like to apply a thin layer of mulch around the base of the plants. Shredded bark or pine needles work wonders for retaining moisture and suppressing weeds that might compete with your young divisions.
The Pinching Technique
To get those classic, round, flower-covered mounds we all love, you should “pinch” your mums. When the new growth reaches about six inches tall, use your fingers to snip off the top inch of each stem.
This encourages the plant to branch out and become bushier. You can repeat this process every few weeks until early July. Stop pinching after the Fourth of July to allow the flower buds to form for fall.
Fertilizing Your New Plants
Wait about two or three weeks before applying any fertilizer. You want the roots to begin “searching” for nutrients first. Once you see new green growth, a balanced, water-soluble fertilizer is perfect.
Avoid high-nitrogen fertilizers late in the summer, as this can lead to lots of leaves but very few flowers. Focus on phosphorus-rich blends as you head into the blooming season.
Troubleshooting Common Issues After Dividing
Sometimes, despite our best efforts, things don’t go exactly as planned. If your divisions look a bit sad or wilted after a few days, don’t panic! Most mums are tough enough to bounce back.
One common issue is temporary wilting during the heat of the day. If the plant looks better in the evening when it’s cooler, it’s just dealing with some minor transplant shock and will likely recover.
However, if the leaves start to turn yellow or brown and stay that way, you may have an issue with drainage or overwatering. Ensure the soil isn’t sitting in a puddle of water.
Dealing with Pests
Freshly disturbed soil can sometimes attract curious garden pests. Slugs and snails love the tender new shoots of divided mums, so keep an eye out for telltale slime trails.
If you see pests, you can use organic solutions like copper tape or crushed eggshells around the base of the plant. A healthy, well-watered mum is usually strong enough to withstand minor nibbling.
Winter Protection
For the first winter after division, it is a good idea to give your plants a little extra protection. Once the ground freezes, add a thicker layer of mulch (about 3-4 inches) to prevent frost heaving.
Frost heaving happens when the soil freezes and thaws, pushing the shallow roots of new divisions out of the ground. A good mulch “blanket” keeps the soil temperature stable.
Frequently Asked Questions About how to divide chrysanthemums
Can I divide mums while they are blooming?
It is possible, but I don’t recommend it. When the plant is flowering, it is using all its energy for the blooms. Dividing it then causes extreme stress and usually results in the flowers wilting immediately and the plant struggling to survive the winter.
How often should I divide my chrysanthemums?
For the best results, you should plan to divide your mums every two to three years. This frequency keeps the plants vigorous, the flowers large, and the centers from becoming woody and unattractive.
Do all types of mums need to be divided?
Most perennial garden mums (hardy mums) benefit significantly from division. However, the “florist mums” often sold in grocery stores are usually treated as annuals and may not survive the winter long enough to need dividing in the first place.
What if my division has no roots?
If a piece breaks off with no roots at all, it is essentially a cutting. You can try to root it in a pot of moist vermiculite or perlite, but it is much harder to grow than a division that already has a healthy root system attached.
Conclusion: Go Forth and Multiply Your Garden!
Now that you know how to divide chrysanthemums like a pro, there is nothing stopping you from having the most spectacular fall display in the neighborhood. It is a simple, satisfying task that connects you deeply with the rhythm of your garden.
Remember, gardening is a journey of learning and experimentation. Don’t be afraid to get your hands dirty and try these techniques on your own plants. The rewards—healthier flowers and a fuller garden—are well worth the effort.
Take a walk through your garden this spring, identify those overgrown clumps, and start splitting! Your mums will thank you with a riot of color come autumn. Happy gardening!
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