Scientific Name: Cosmos, or Mexican Aster

Height: Depending on the varieties; 18 to 60 inches

Width: 12 to 24 inches

Spacing: 12 to 36 inches

Sun: Full, but can tolerate partial

Bloom Time: Early summer to early fall

Water: Once a day unless temperatures rise

Soil Type: Loose, rich, fertile soil

Soil pH: 6.0 – 6.8

Zones: 2 to 11

Uses/Styles: Beds and borders, cottage, backdrop, accent

Flower Colors: White, pink, yellow, red, orange, and blends

Attracts: Bees, butterflies, and birds

Special Features: Whimsical appearance, cut flowers, drought tolerant, attracts pollinators, and great for containers

Basic Information

Cosmos have over 20 different varieties and an array of colors that’ll attract bees, butterflies, and birds. They can deal with poor soil conditions, and once established, they can become drought-tolerant. Though they are considered annuals, they are still highly sought after due to their self-sowing attributes that allow for a longer bloom period.

Versailles Red.

Planting and Care

Sowing cosmos is fairly easy and quick to do. Use a packet of seeds (or last year’s seeds that you’ve sown yourself), scatter in a full sun and well-draining location, place a thin layer of soil on top, and water. Before you scatter your seeds, add a balanced fertilizer into the soil so that they are able to become full, healthy plants. Make sure to come back and water at least once a day depending on the temperature. Seeds should sprout through within 7 to 14 days. From there, keep an eye out on pests and critters who may want to take a nibble or two. You can use chicken wire or shade cloth to cover or surround the area.

Depending on the variety and size of the plant, you may need to use stakes to help support both the root system and the stem of the plant(s). Anything that grows 4 feet or taller should have support systems in place so that they don’t run the risk of falling over and snapping.

Once your cosmos have started to flower and are getting their second or third flowers, start deadheading your first flowers. This will help promote more flowers but will also allow for the stem to focus on becoming more structurally sound. You can either use those flowers and place them in your house for decoration or you can allow for the flowers to dry out and use the seeds for either this year’s crop or next year’s crop.

Cosmos bippanatus and Cosmos sulphureus

Cosmos bippanatus: Native to Mexico. The distinguishing features include a bright yellow center with daisy-like petals. You may see them in semi-double or double-petalled form. They range from 2 to 5 feet but can sustain upwards to 8 feet. Anything above 4 feet should have a support system.

Two popular varieties include:

Seashell: The petals are rolled around and somewhat resembles a seashell. They come in shades of white, pink, and rose, and can grow to be 3 to 4 feet tall with the flowers being 3 inches in diameter.

Sonata: The petals are frilly towards the edges and have fern-like foliage. They grow to be 18 to 24 inches tall and have colors from pure white to shades of rose, pink, and cherry.

Two popular varieties include:

Cosmos sulphureus: Native to Mexico. Thrives wonderfully in dry, poor soil, and can become weak if they are placed in rich, fertile soil. Most grow between 1 to 3 feet but can go up 6 feet. They too have semi-double or double-petalled form but usually range in yellows, oranges, and vibrant reds.

The Diablo: The petals are semi-doubled and are scarlet/orange that looks like a flame. They grow to 4 to 5 feet tall and are excellent for cut flowers.

Dwarf Gold Sulphur: They grow to be 18 to 24 inches tall and produces semi-double gold-yellow flowers. The petals are about 2 inches in length.

Cosmos atrosanguineus

Cosmos atrosanguineus: Known as the Chocolate cosmos. Semi-double petals smell like chocolate and have a deep crimson color. The flowers grow to be 3 inches in diameter. They grow from 15 to 19 inches tall. It’s reported to be extinct but some claims say it’s in very remote, select areas. They are a perennial if you dig up the bulbs before the danger of frost. Place the bulb(s) in a cool, dry, dark area until spring.

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