Know When To Cut Back Black-Eyed Susan For Optimal Growth

old, moldy black eyed susan

As a prolific bloomer over the summer months, black-eyed Susan, also known as Rudbeckia, will naturally benefit from being cut back occasionally. Learn here when to get out the clippers and cut back your plants, so they remain strong and productive through the whole growing season.

Black-eyed Susans benefit from being deadheaded throughout the summer to promote fresh blooms. The plants can be cut back in the fall after the first frost to tidy up the garden or prevent self-sowing. Or, leave the old plants in the garden over winter to feed birds and provide shelter for wildlife.

Now let’s dig into a few details for whichever solution is the right fit for you and your flowers.

Should black-eyed Susans be cut back after flowering?

There are two times that you should cut back black-eyed Susan after flowering. The first time is an ongoing process called deadheading, and the second time will be after the flowers have finished blooming for the season and can be cut down to soil level.

Deadhead throughout the blooming season

You should deadhead your black-eyed Susans throughout the summer to encourage new blooms. Deadheading means removing old flowers from the plant once they begin to fade. The plants will continue to produce flowers even without deadheading, but using this technique will result in more flowers than if you skip it.

To get the best results with deadheading, cut the stem with the old flower all the way at the base, just a few inches up from the soil line. This deep cut will encourage new leaf and stem growth instead of relying on the old stem to produce a new bud.

dead black eyed Susan flower in the garden
This black-eyed Susan is overdue for deadheading. Alternatively, you can leave it a bit longer and harvest seeds from it.

Even though some rudbeckia varieties are perennial, their goal is still to produce seeds by the end of the season, so by removing spent blooms, you’ll keep the flowers coming by preventing the plant from going to seed after the first round of flowers.

To learn more about deadheading, check out this article: Should You Deadhead Cut Flowers, Too?

Cut back completely once the plants are done for the season

Once fall has arrived, and frost is imminent, you can cut back your black-eyed Susan plants entirely. You don’t need to pick and choose which stems you cut and where; shave the whole plant down to several inches above the soil level, and it will grow back next spring.

The three images above show the benefit of cutting back your mature black-eyed Susan flowers. The plants had grown well most of the summer, but had gotten too tall and flopped over. I cut them back heavily, fertilized them, and about a month later, I have a new flush of flowers on my plants.

Need some good clippers for the job? Check out my two favorite pairs.

My favorite garden shears

I constantly misplace my garden shears and clippers, so I’ve tested a lot of pairs. Good thing these ones have red handles to help me keep track of them!

If you wait until after the first frost has arrived, that’s fine, too. Depending on how hard the freeze is, some of the leaves may be soft and mushy, so they’ll be easy to remove. The old stems might still be standing, but just cut those down and compost them.

If you get freezing winters, it’s good to mulch the soil around the remaining plant. Several inches of organic mulch will help insulate the soil, keeping the temperature just slightly higher than the air around it. Perennial varieties, such as Goldsturm will come back even in cold climates, but they’ll still appreciate a layer of mulch.

If you aren’t sure which growth habit your flowers have or you want to learn about the different types, check out this post, Are Black-Eyed Susan Annual Or Perennial Flowers?

Should black-eyed Susan be cut back in the fall?

Fall is a great time to cut back rudbeckia flowers. They are finished blooming for the season, and cutting them back will help tidy up the garden for the upcoming winter. In spring, the plants will resume growth from dropped seeds or established roots if they are perennial.

This video is from my garden, as I deadhead and cut back my flowers.

If you don’t want the flowers to spread throughout your garden or flower bed, then fall is a perfect time for you to cut back the plants to prevent self-sowing.

Keep plants from spreading

Black-eyed Susan is known as a prolific self-seeder. As the flowers fade and go to seed, they drop to the ground and germinate easily near the parent plant. The seeds may sprout soon after dropping to the ground if the growing season is long. Or, they may overwinter on the ground and pop up in the warm weather of spring.

Either way, it’s not uncommon to have one black-eyed Susan plant start spreading throughout the garden or flower bed starting in the second year and beyond. Some gardeners might be happy to have their flowering plants multiply, while others need to keep the plant in one area only, perhaps due to having a small garden.

To keep black-eyed Susan from spreading, remove all the old flowers throughout the season before they go to seed. If you have a perennial variety in the garden, such as the popular Goldsturm, the roots will still spread but much more slowly than through self-sown seeds germinating on their own.

Can I cut back black-eyed Susans in the spring?

Black-eyed Susan can be cut back in the spring if you want to leave the plants to overwinter in the garden. Leaving the plants behind will provide food for backyard birds and shelter for hibernating insects, and cutting back the old plants will be part of spring clean-up.

Leave dead foliage and seed heads for birds and insects

Black-eyed Susan flowers make hundreds of small seeds that birds such as goldfinches and cardinals love to eat, so try leaving old plants in the garden through the fall and winter. The birds will perch on the seed heads to pick out the seeds and use the height advantage to scout for insects to eat.

Beneficial insects and bees will also happily make a home in the dead foliage and stems of old flowering plants. Ladybugs hibernate in brush piles over the winter, so if your black-eyed Susans are part of a naturalized garden or wildflower bed, then it might be a desirable winter habitat.

When you do clean up your old plants in the spring, wait until the weather has warmed up for at least a week so that the overwintered insects have woken up and can move out of the way before you dump the plant debris in the garbage. Or, preferably, take it to your compost pile and let the insects leave when they’re ready.

To learn more about fall clean up and when you might want to wait for spring, head over to this article, Cut Back, Compost, Or Continue: A Quick Guide To Fall Flower Clean Up.

While you’re checking out other resources, be sure to read through Black-Eyed Susan: A Complete Guide To Growing, to make sure you’ve got all the details you need to help your flowers thrive.

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