How to Care for Mexican Aster Plant?

Mexican Aster is a wildflower popular for its beautiful blooms and attractive foliage. Its Botanical Name is Cosmos bipinnatus. Mexican Aster is known as the Cut Leaf plant due to its thin leaves. It is one f the easiest spring flower to grow from Zone 1 through 10. You can directly sow the Mexican Aster seeds in the flower beds and forget about them. These Aster flowers have a moderate to high germination rate. So getting a seedling from its seed is not a big problem. Plant care should be your main concern if you want huge blooms in decent quantity. Today we will discuss how to care for the Mexican Aster plant. To learn more keep reading.

How to Care for Mexican Aster Plant?
How to Care for Mexican Aster Plant?

Check out this post: How to Grow Mexican Aster: Cosmos Bipinnatus

How much care does Mexican Aster Plant need?

Mexican Aster is an easy-to-grow plant. It does not require heavy care or maintenance other than obvious. Healthy soil with good drainage and proper sunlight is sufficient to keep the plant healthy.

Other than these, you may occasionally lookout for any pest or disease in the plant. keep the soil clean and free of weeds. Prune the Mexican Aster plant once flowering ends. A little support or stake is good for these plants.

Overall, you may require a couple of hours every week to care for Mexican Aster plants.

How to Care for Mexican Aster Plant?

Plant care is an essential part of gardening. Some plants need more care and maintenance than others. Others may do well without any extra effort. The American Aster plant comes in this second category.

Mexican aster plants don’t require much care. It is very to maintain and care for Mexican Aster plants. It requires basic plant care. Don’t worry it’s very easy. Only a couple of hours every week is sufficient to accomplish these tasks.

Carefully follow the given steps and keep your Mexican Aster plants healthy and full of blooms.

Soil Treatment

Soil treatment and preparation is the first step of plant care. You can use any type of soil for Mexican Aster plants. Although a healthy nutritious soil with balanced ph is good to use.

Add 2-3% fungicide in total soil by volume. 1 spoon fungicide can be used for 2 to 3 pots or containers. Soil treatment is important especially for controlling soil-borne diseases.

Commercial gardeners also use the dry fry technique to kill fungal spores in the soil. You can dry fry container soil by heating it at 100 degrees celsius or more for 15 minutes.  Often we use microwave oven for this purpose.

Check out Everything to know about raised garden beds

Weeding and Raking

Rake the soil before seeding. Proper raking can help in cleaning as well as leveling the soil.  You can also turn the soil to break and loosen the surface before seeding. It will help in proper soil aeration that eventually promotes faster root growth.

Once Mexican Aster seedlings are ready in the garden. you have to look out for different plants that can compete for space and nutrition. We call them weeds. You must remove the weeds and keep the surrounding area clear for airflow.

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If you want to know more about weeding then read What is the Importance of Weeding?

Support or Staking

Mexican Aster plant has a delicate stem structure. It can benefit from support or staking. It is not a vine or creeper so you have to tie knots to hold stems up with supports.

Long sticks, wire nets, and stakes are helpful for these plants. Install support during transplantation of seedlings or once they reach 4 to 8-inch height.

The stems are quite delicate and tender. So use threads or tie ribbons to hold them above the ground. They can get infected easily from the soil if stay in contact for long.

Read for more details: Easy Ways to Support Vegetable Plants

Usual Pruning

Pinching the Mexican Aster Plants once it grows to 6-8 inches high is essential. Initial pinching or Pruning can encourage the plant to develop new branches. These new branches will grow and develop flowers.

Prune the Plant to 40% of its height from the ground once flowering ends. It will readily develop new branches and start blooming again in 40 days. Meanwhile, the previous seeds will spread in the soil. They will germinate and fill up the space within each plant row. This will ensure continuous blooming until the first frost.

You have to be precise as early pruning of large stems can slow down flowering. Also, it will not bloom after mid-summer in the most zone. This is the time for reseeding the ground for further growth.

Fertilization and Watering

Mexican plants need 1-inch water per week to continue blooming. Though it can thrive easily in dry rough sandy soil. It will rarely bloom even with heavy fertilization. too much fertilizer, lack of moisture, and sunlight together can force the plant to grow dense foliage instead of flowers.

Water deeply once or twice every week to get continuous flowering in your plants. If possible then install a drip irrigation system to save water and keep the plants hydrated.

All-purpose liquid fertilizers and NPK 10:20:10 are ideal for Mexican Aster Plants. Apply these only once in 15 days and keep the plants well hydrated. These fertilizers will increase blooming though it is not necessary to use if the soil is healthy.

Pest Control

Just like any other flowering plant, Mexican Aster is also prone to a few pests and diseases. You should avoid dripping water on the foliage and keep the soil moist but not soggy.

Use Neem oil twice every week to deter most of the common garden pests away from Mexican Aster plants. If you Asters are having any serious pests or disease problem then read Mexican Aster Pests and Diseases for more help.


Regular harvesting is also essential to maintain the good health of Mexican Aster Plants. It will encourage the plant to develop more flowers and keep it full of fresh blooms. If you let the flowers stay long in the branches. Then the plant will start developing seeds and stop further flowering. It will spend most of its resources on the development of seeds. This will result in low flowering.

Therefore, You must harvest flowers just a day or two after blooming. Cut the flower stalk from 3 inches below the flower head. Keep them in a flower vase with water and cut flower liquid and enjoy for 10 to 15 days.

Seed Collection

Leave a few flowers in each branch at the end of the flowering season to mature. these flowers will develop seeds. You should collect the seeds before they fall off in the soil. It is true you cannot save all of the seeds, yet try to save as much as you can.

Dry out the seeds in part shade for 2 days and store them with fungicide. You can sow these seeds anytime during spring till the summer season.

Mexican Aster seeds can stay alive in the soil for 1 year. You can save and store these seeds for 18 months or more with good viability.


You can easily Care for Mexican Aster Plant. Just keep the soil moist and well-nourished. Allow the plant to receive full sun and control pests and disease. That’s it there is nothing more to do. Spend 1 or 2 hours for your Mexican Aster plants every week and they will reward you with lots of blooms.


Hi, My name is Sukant. I am an I.T professional. Gardening for me is not just a hobby, it's a way of living life with nature. My Ancestors were Commercial farmers: So I personally feel attached to the green. I am not an expert, I'm here only to share my gardening experiences. It's always Refreshing.

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