Is your garden looking a little tired? Those perennials might need dividing. August is a great time to split overcrowded plants and turn them into multiple healthy ones.
The best part? Dividing perennials is easier than you think, and it’s basically like getting free plants.
Signs Your Plants Need Dividing
Most people don’t realize their perennials are overcrowded until the plants are already struggling. Here’s what to look for:
- Donut Effect: The center looks dead or hollow while the edges are still growing
- Fewer Flowers: Bloom production has dropped off
- Flopping: Plants fall over and crowd their neighbors
- Too Big: Clumps have outgrown their space
Divided perennials can produce up to 3x more blooms than crowded ones. That’s triple the flowers for one afternoon of work.
How to Divide Perennials
The process is straightforward, but timing and prep matter.
- Water the day before: This reduces stress on the plant
- Dig up the whole clump: Get underneath the roots
- Separate into sections: Shake off extra soil and pull or cut apart into chunks
- Replant right away: Set divisions at the same depth as before and water well
Think of it like giving your plants more room to grow. A little stressful at first, but they’ll be healthier for it.
8 Perennials to Divide in August
1. Daylilies
Divide every: 3-5 years
These tough plants keep their spectacular blooms when divided regularly. Their roots are thick and stubborn, so you’ll need a sharp spade. August works well since they’ve usually finished flowering but still have time to settle in before fall.
2. Bearded Iris
Divide every: 3-4 years
Bearded irises make it pretty obvious when they need dividing. Look for that hollow center. Only replant the younger outer sections.
The older middle parts won’t produce much. After dividing, trim the leaves back to 4-6 inches. These need full sun and good drainage.
3. Black-Eyed Susan
Divide every: 3-4 years
These cheerful flowers get crowded quickly. When packed too tightly, they become floppy and weak.
Divide them into chunks with good root systems, and they’ll stand up straight again. They like well-draining soil that doesn’t stay soggy.
4. Coreopsis
Divide every: 2-3 years
These sunny perennials keep spreading until they wear themselves out. Dividing every few years keeps their energy focused on blooming rather than just spreading.
Use a sharp tool to slice clumps apart. They actually do well being planted in warm weather.
5. Shasta Daisy
Divide every: 2-3 years
New to dividing plants? Start here. Shasta daisies are quick and forgiving. They need to be split regularly to prevent legginess and keep that classic daisy shape.
Like most plants on this list, they love the sun and handle heat well.
6. Yarrow
Divide every: 3-4 years
Without regular division, yarrow develops woody centers and can spread too much. Division keeps them healthy and under control.
Since they’re drought-tolerant, they need very little care beyond occasional dividing. Great if you’re busy or tend to forget about watering.
7. Garden Phlox
Divide every: 3-4 years
Garden phlox tends to get mildew. Regular division helps improve air circulation around the plants.
The payoff is healthier growth and those pretty, fragrant blooms that butterflies love.
8. Sedum ‘Autumn Joy’
Divide every: 4-5 years
When your sedum starts flopping over, it’s time to divide. These are so easy to separate that you can often do it with just your hands.
Give them full sun and occasional water, and they’ll bloom for months. Pollinators love them too.
Why Division Matters
The difference between new and experienced gardeners is knowing when to divide. It’s not just about making more plants. It’s about keeping them healthy, getting more blooms, and helping them live longer.
Here’s something worth knowing: a study from the University of Illinois Extension found that regularly divided perennials can live up to 15 years longer than ones that are never divided. That’s a solid return on a bit of garden work.
So grab your spade and give those perennials some attention this August. Your effort now will make next year’s garden much better.