Should Asters Be Cut Back After Flowering?

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Asters bloom into massive, eye-catching bushes with colorful flowers. While these flowers are beautiful to look at, they cannot stay in the bush forever.

You should cut asters back after flowering to help the plant grow back faster and stronger. Leaving flowers on the bush for too long can cause unsettling discoloration throughout the entire plant. Cutting back also creates less bulk that can house unwanted pests.

In this article, I’ll explain why you should cut back your asters once they fully flower. Additionally, I’ll discuss what to watch out for as your aster reaches its peak bloom. 

Reasons Why You Should Cut Back Asters After Flowering

It may be tempting to keep your aster flowers around as long as possible, but doing so can cause more harm to the health of your bush over time. 

To give your asters the best opportunities to grow, you need to cut them back anywhere from 6 to 8 inches (15 to 20 cm) so that there is still a decent amount of the main plant left (source).

Asters need to be cut for reasons relating to the plant’s overall health and to the plant’s presentation over time. Cutting the flowers off may seem counterproductive, but it is instead an action that allows the plant to flourish more in the future. 

It Ensures Better and Healthier Growth

Cutting back your asters after blooming leads to a future plant that is bigger, healthier, and stronger. The process helps keep the bush in great shape and promotes an increase of blooms for the next time the plant is ready to flower again.

See Does Pruning Stimulate Growth? You Need To Understand This!

Because the stems of the main aster plant are already present, the old flowers just need to be cut and removed so that new flowers can grow in their place. Not only does this help to regulate the growth cycle of the aster plant in accordance with the seasons, but it leads to plants that are just as healthy as the ones that are cut off. 

When plants are trimmed down, it can also help lead the way to a process called propagation (source). Propagation occurs when new plants extend or grow from the point of the main plant’s stem and not from something like a seed or bulb.

When cutting these flowers off to produce new ones, the selected flowers must be in good shape before cutting. This is to ensure that the flowers that bloom after are also in good health. Additionally, doing so means that you can discard the flowers entirely or keep them to use in your personal flower arrangements. 

See How To Keep Your Asters From Getting Leggy.

It Manages Overgrowth 

In addition to encouraging more blooms, you should cut asters back after flowering because the plants can easily become too large and overgrown. Because asters are known to grow very large, they can quickly develop to a point where they are too full or block areas such as sidewalks and pathways. 

Additionally, the overgrowth of the asters also leads to problems like an increase in pests and diseases. Common insects that you might find hiding around your asters include:

• Aphids
• Lace Bugs
• Leafhoppers
• Beetles

These pests create an obnoxious presence around your plants. They may also cause lasting damage that may go unnoticed for a significant amount of time (source).

These insects also prefer the conditions of overgrown asters that cause the plants to sag down or turn brown. The decline of an asters’ health creates optimal habitats for these pests to thrive and reproduce.

By cutting your asters back after they flower, you eliminate opportunities for pests to populate and save your plants from future infestation problems. 

It Prevents Harmful Diseases

When an aster reaches full bloom and starts to get too big, diseases can begin to infest the plant. If the asters are not cut down after flowering, these harmful diseases have more opportunities to excel out of control. 

Like many plants, asters are susceptible to many harmful diseases and infections that alter their overall health and growth patterns (source). Conditions that can affect asters include the following: 

• Botrytis Blight
• Leaf Spots
• Aster Yellows
• Wilting
• Mildew and Fungal Growths

These awful diseases cause your asters to decay, wilt, and change colors. These changes are preventable if the asters are cut because the action keeps the bush fresh and healthy. 

Also, cutting asters after they have flowered gives the opportunity for the bush to regenerate healthy parts of itself. During the cutting process, many diseased pieces of the plant that may have occurred during the blooming process can be removed. In doing so, the asters can return to their full strength the next time it is time to bloom. 

It Removes Temperature Damage

Asters occasionally face damage from the sun or intense heat conditions. By cutting back the asters, you not only remove the damaged portions but also allow the plant to try to come back healthier than before. 

Research conducted on different asters revealed that their growth is inhibited when exposed to unsettling temperatures (source). In addition, sun damage leads to decreased blooming and poorer health of the overall plant. 

This result is because asters can burn or dry up in excessive heat, especially in areas where the temperatures are constantly high or there’s a lack of water. It can be difficult for them to grow back when they get to this point unless the floral ends are cut off. 

To keep your asters safe from sun damage inflicted upon them, cut them back when you notice that they appear dry or frail. Doing so will leave you with the expectation of healthy blooming plants for seasons in the future.

Final Thoughts

To allow asters to maintain a healthy appearance and growth cycle, you must always cut them back shortly after they flower. You do not have to cut them back as soon as they start to bloom, but leaving them uncut for a long time may do more damage in the long run. 

Additionally, cutting your asters removes damaged parts of the plant that prevent it from growing to its fullest. Sun damage and other issues can decrease the health of the asters while also blocking future growth.

Recommended Reading:

• When Is It Too Late To Plant Aster Seeds?
• Why Won’t Your Aster Seeds Germinate?
• Why Are Your Asters Drooping? Common Causes and Fixes