How to Grow and Care for Cosmos Flower

Cosmos Flower


Plant Type: Annual flower
Family: Asteraceae
Sun Exposure: Full sun
Watering: Regular - moist but well-drained soil
Colors: Purple, yellow, white, pink, magenta, orange, red
Size: 1–6 feet tall, 1–3 feet wide
Hardiness Zones: 2–11
Soil Type: Chalk, clay, loam, sand
Soil pH: 6.0–6.8 (slightly acidic)
Propagation: Seeds
Toxicity: Non-toxic

The cosmos flower is an easy to care for plant that blooms annually. It has flowers that look like daisies that grow in bright, colorful shades. So, if you are new to the hobby of gardening and would like a fun, cheerful bloom, the cosmos flower is a great choice.

These flowers are both beautiful and low maintenance. Your plant will tolerate the heat and survive through the first frost of the winter season. Cosmo flowers provide a pop of color to your garden and a few simple things keep them happy and healthy. Being a cottage flower they mix well with most garden plants. It will fit well amongst your other blooms.

Whether you are a new or expert gardener, you will enjoy growing this plant as it is easy to care for. This will give you more time to care for your fussy garden members. Check out the details in this article. 

Cosmos flower

About the Cosmos Flower

Cosmos flowers are bright and colorful. They are native to Mexico, South America, and the southern region of the United States. These plants are annual blooms but can be perennials depending on where you live. There is also a perennial variation that grows from tubers.

These plants can grow tall. Depending on which variety you select, the cosmos flower can grow up to 6 feet! They typically spread 1-2 feet in the ground.

The cosmos plant begins blooming in the early summer months and can survive through fall. They will last through the first frost in most scenarios.


How to Grow the Cosmos Flower

Cosmos plants are one of the easiest plants to grow from seeds. You should begin seeding your cosmos flower indoors. You can start this process about 4-5 weeks before your average final frost date in your area. By seeding them indoors before the final frost, they will be ready to plant in the ground come early spring. If you are seeding the cosmos flower indoors, you can use a tray to do so.

To make sure your seeds are happy, place them in a high-quality seed mix that is soilless. Dampen the seeds before you place them in the tray. You will then ready your tray by adding a shallow amount of the seed mix. The cosmos flower needs to be sowed shallowly. Placing them 1/8 inch deep should do the trick. You’ll want to make an indent with your finger before placing the seed in the shell of the tray.

Water your tray and cover it with a plastic dome. This will help lock in moisture while your seeds are germinating. Keep your tray in a warm and sunny spot in your home. In about two weeks, you should begin to see your seeds sprout. A week before you plan to move them outdoors, take them outside during the day to harden.

You may also start your seeds outdoors or buy an established plant from a garden center or nursery. The cosmos flower is an easy plant to grow under any circumstance. If you are putting seeds or an established plant into the ground, make sure the final frost has passed. These plants can also live in containers.

Mexican aster

Propagating Your Cosmos Flower

The cosmos flower is self-seeding, so it is easy to propagate your plant. Collect the dried seeds and plant them the next season. It’s that simple!


Cosmos flowers varieties. Can they be purple?

There are two types of cosmos flowers. The Cosmos sulphureus, which is native to Mexico, South America, and parts of the United States. These plants are drought tolerant and love hot weather. If you live in a hot climate, this is the variety for you. On the other hand, the Cosmos bipinnatus is the more common variety. It is the more colorful of the two varieties but less tolerant of heat.

The cosmos flower comes in several varieties. When selecting a variety to add to your garden, consider what colors and sizes interest you. Some of the varieties include the bright light mix (yellow, orange, and red flowers) and the cosmic orange. Other varieties are peppermint candy (white, purple and pink flowers). Also seashell series (a mix of colors), and the chocolate cosmos (dark red flower). Most of these varieties get to be about three feet tall except for the cosmic orange variety. Cosmic orange only gets to be about 1-2 feet tall.

cosmos flower

How to Care For Your Cosmos Flower

Watering Your Cosmos Flower

These plants are incredibly drought tolerant. You will not need to water them unless there is a prolonged drought. If you notice the soil of your cosmos flower is excessively dry, add a little bit of water. It is important to avoid overwatering the cosmos flower. They are at risk of root rot when they have too much water.

Pruning Your Cosmos Flower

Another reason these plants are so easy to care for is the fact that they do not need to be pruned often. The most maintenance you will have to do on these flowers is the occasional deadheading. Once most of the flowers have faded, shear about one-third of the plant. This will help produce more flowers and leaves.

Mexican aster

How to Fertilize Your Cosmos Flower

There isn’t a need to fertilize the cosmos flower. Although if you have a plant that is struggling, you can add a little bit of a simple fertilizer to it. Be careful, these plants can suffer if they receive too much fertilizer. If you over-fertilize the plant, the leaves may grow but the flowers will not. It is best to avoid fertilizing the cosmos flower unless you are concerned about the health of the plant.


These plants are also easy when it comes to soil type. The cosmos flower will even thrive in poor soil that most plants would struggle in. They prefer neutral or slightly acidic soil. A medium amount of soil moisture is a good idea for these plants, but they can survive in dry soil. They cannot thrive in overly wet soil, so avoid that. While they do well in most soils, rich soils can cause the plant to get too tall. This might lead to your plant falling over.


The cosmos flower loves the sun. Make sure you place your plant in a spot that sees full sunlight. They can survive in partial shade if needed, but you will see less impressive blooms that way.


While the cosmos flower can thrive in most climates, it does best in those that are similar to where they come from. These plants are native to Mexico, Central and South America, and the southern part of the United States. Due to this, they love hot weather. As long as your cosmos flower will see a hot summer, they will be happy. Humidity does not matter much to these plants. They will often survive past the first frost but will fade after that.

Pests and Disease

The cosmos plant is often not affected by pests and disease. You may encounter aphids or thrips, but they can be hosed away. In the worst of circumstances, you can use an organic insecticidal soap on the infected area. Like most plants, they can get fungal infections or mold. You can avoid this by making sure your flowers are spread apart when planted and that they do not get overwatered.

cosmos flower

Fun Facts About the Cosmos Plant

These plants are the perfect cut flower! Take your shears outside and cut the mature flowers off of the plant. Bring them inside and stick them in a vase to liven up your living space!

These plants are not deer or rabbit-proof. Those little critters might take the occasional nibble out of your cosmos flower. Yet, it is not their first choice. If you are concerned about wildlife eating your plant, they will likely avoid them unless they are desperate.

The cosmos flower does attract bees, butterflies, and birds. Pollinators will love visiting your yard once you add the cosmos flower to your garden.



The cosmos plant is a fun and colorful bloom to add to your garden. It requires little work from the gardener. These are the type of plants you can plant and forget. They can tolerate drought and get most of their water without your help. They thrive in most soils, even those other plants can’t stand. They love sunlight and heat. As long as you can provide the cosmos flower with a sunny spot, they will be happy.

These plants do not need fertilizer or pruning. They can grow straight in the ground with ease or liven up a container. The cosmo flower is one of the easiest plants you can grow! They will brighten up your garden without the hassle some other flowers need while fitting in well with your resident flowers.Are you ready to grow your own cosmos plant? Share this article on social media and let everyone know about your new gardening venture! Make sure you send this guide to a friend who needs a low-key plant to add to their garden.

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