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What To Do With Black Eyed Susan In The Fall – How To Cut Back & Divide

Wondering how to care for your Black Eyed Susan as they begin to die back this fall? And what to do with a few clumps that have perhaps grown a bit too large over the years?

Today’s article is all about fall care for your Black Eyed Susan plants – including how and when to cut them back, and how to divide and transplant ones that have overgrown their space.

Black Eyed Susan is a heavy flowering perennial (there are annual varieties as well) that blooms strong from mid to late summer. This highly drought and deer resistant plant is a popular choice for home landscapes. And it’s easy to see why!

fall care - black eyed susan
With thick blooms of daisy-like flowers, Black Eyed Susan is a perennial favorite. Add in that it is drought and pest resistant, and it is easy to easy why so many gardeners love this perennial.

With bloom periods that can last for nearly a month, and the ability to grow in all kinds of soil types and climates, it has serious staying power. In fact, with a bit of deadheading in late summer, it will often bloom again for a second time through fall.

But eventually, as the days grow a bit shorter and temperatures begin to cool, Black Eyed Susan will eventually begin to die back. And that is the perfect time to spring into action with a little fall care. Not only to prepare them for even better flowering next year, but to keep them healthy as well.

When To Cut Back Black Eyed Susan

When it comes to the best time to cut back Black Eyed Susan, it really boils down to a matter of personal preference. They can be cut back in the fall or spring, without harming the plant’s bloom cycle either way.

flowres drying out
As cool weather begins to settle in, Black Eyed Susan will begin to fade. The see heads that dry and form on top of the stems are actually a great source of nutrition for many birds and other wildlife – and for this reason, many gardeners choose to leave them in place.
Cutting Back In The Fall

Many prefer to cut the plants back to the ground as soon as the flowers and stems begin to fade. This is certainly a great way to keep flowerbeds neat and tidy.

Cutting back in the fall can also help protect plants from disease, mildew and pests. When allowed to overwinter, the decaying foliage is an easy place for both to hide out.

But there is another reason many choose to cut back Black Eyed Susan earlier. And it all has to do with trying to keep volunteer plants from becoming an issue.

In some locations, the plant can begin to crowd out other perennials if allowed to spread to quickly. And by allowing seed heads to remain and scatter, this can sometimes happen quickly. But cutting the stems back early eliminates this issue.

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Allowing Plants To Remain

There are also many gardeners who prefer to keep the plants up through winter. And they do so for a couple of great reasons as well.

For starters, the seed head of Black Eyed Susan is a great source of food for birds. And when allowed to dry on the stems, it can help feed them through the long, cold winter months.

In addition, allowing the seed heads to remain can mean even more plants for the following year – and some welcome that with open arms.

black eyed susan in the fall
Black Eyed Susan is a prolific re-seeder. In addition to helping feed wildlife, the seed heads easily scatter to form new plants.

Black eyed Susan reseeds quite easily, and is often spread to new places by wildlife. Again, it really comes down to a matter of personal preference. That is, unless you have an issue with mildew or disease already appearing in the fall.

Disease & Mildew – Fall Care For Black Eyed Susan

Black eyed Susan will sometimes become infected with mildew and disease as fall approaches. Especially with a summer that has been unusually wet or cooler than normal.

To prevent infection from coming back and or spreading, it is important to take action if your plants show any sign of mildew or disease. Allowing these plants to overwinter can lead to increased disease issues the following year and beyond.

At the first sign of disease, cut any plants that show signs of infection down to the ground. This include both foliage, stems and seed heads and flowers.

Do not attempt to compost any plants or foliage that have been removed for disease and mildew. Unfortunately, the average home composting bin simply doesn’t reach high enough temperatures to kill the disease off. The result is compost that can easily re-infect plants when used in the garden and flowerbeds.

Dividing & Transplanting Overgrown Plants – Fall Care For Black Eyed Susan

Black Eyed Susan should be divided and split every three to five years to keep plants healthy and blooming strong. If allowed to grow too thick, the roots begin to crowd one another out. Once this occurs, blooming cycles can be shorter and less intense.

dividing black eyed Susan
When allowed to grow too dense, Black eyed Susan can begin to bloom less with each passing year. Regular dividing can prevent this and give you additional plants for your landscape.

Dividing can be done in the spring or fall with success. However, of the two, fall is much easier to see which plants have grown a bit too large for their space.

If dividing in the fall, it is best to divide as soon as the plant’s foliage begins to show signs of dying back. This will allow enough time for the new divisions to establish in the soil before winter sets in.

How To Divide

To divide, begin by cutting back the foliage to within a few inches of the surface of the soil. This will make it easier to see and divide the plant once it is out of the soil.

Dig around the outer edges of the plant with a sharp shovel. Once you have cut the edges, dig down deep and lift the plant from its planting hole.

Next, flip the Black Eyed Susan’s roots over and divide into equal sections. Just like with all perennials, the size of your divisions will dictate the size of your plants next year.

Transplant your new divisions into new planting holes, amending each hole with a bit of compost to help provide a bit of power

Mulch new transplants with a few inches of fresh mulch to help protect them through the old winter months. Depending on how warm your autumn is, you may see new growth emerge from the base of the transplants.

This will not harm the plant, and the foliage will simply die back when hit with the first freeze or heavy frost. And once spring rolls around, your new plants will be ready to roll!

For more information on fall care in the landscape, check out our When To Cut Back Perennials In The Fall article on the site. And be sure to check out our Perennial Plant Care page on our sister OWG garden site.

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