Cosmos
Depth 1/4”
Spacing 12-18”
Height: 18-48”
Post Germination Water Needs: Moderate
Light: Full Sun
Days To Maturity: 60-90 days
Cosmos bipinnatus or Cosmos sulphureus
Overview
Cosmos are charming, easy-to-grow annuals known for their delicate, daisy-like flowers that come in shades of pink, purple, white, and orange. The plants have ferny, soft foliage that complements their airy, open blooms. Cosmos are great for attracting pollinators like butterflies and bees and are commonly used in wildflower gardens or as border plants. With a long bloom time from summer through fall, they’re perfect for adding continuous color to gardens.
Planting and Care
Sun Requirements: Cosmos thrive in full sun. They need at least 6 hours of direct sunlight a day to produce the most blooms.
Soil: Well-drained soil is key. Cosmos are quite adaptable and will tolerate slightly sandy or poor soil, but they will produce the best blooms in moderately fertile, well-drained soil.
Watering: Water regularly until the plant is established, then reduce watering as they are fairly drought-tolerant once mature. Water at the base of the plant to prevent wetting the foliage.
Fertilizing: Cosmos don’t need a lot of fertilizer. Too much nitrogen can result in tall plants with fewer flowers. A light feeding with a balanced fertilizer in early spring can encourage strong growth, but avoid heavy fertilizing during the growing season.
Pruning: Deadhead spent flowers regularly to encourage more blooms and prolong the flowering season. Cosmos may also benefit from being cut back if they become too leggy or tall. A slight pruning at mid-season can promote bushier growth.
Companion plants
Zinnias (similar growth habit, adding more color and texture)
Marigolds (bright, complementary colors and good pest control)
Black-eyed Susan (Rudbeckia) for contrast in bloom shape and size
Lobelia (for trailing edges in containers or hanging baskets)
Salvia (for height and more pollinator appeal)
Lavender (for a fragrant and contrasting foliage texture)