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Cosmos bipinnatus
Growing calendar
Typical timing for central Japan (Kanto region). Shift it for your own climate, and record your actual dates.
Guides
- How to Sow Cosmos Seed: Depth, Warmth, Spacing and Thinning
- Cosmos Care: Why Rich Soil and Feeding Give You No Flowers
- Pinching Out Cosmos: When to Pinch and How Much to Take
- The Cosmos Year: What to Do from Sowing to First Frost
- Cosmos Problems: No Flowers, Flopping Stems, Slugs and Mildew
Common problems
Start from what you can see on the plant.
Pests and diseases (16)
Problems recorded for this plant, most serious first.
Fusarium Yellows
Disease
Yellowing starts on the lower leaves, the petioles twist and the plant leans to one side. Vascular tissue browns, growth stops, and heading vegetables may die without ever forming a head.
Powdery Mildew
Disease
White patches appear scattered on the upper leaf surface at first, then the whole leaf is coated in a white powder. Leaves later yellow, brown and die back, and reduced photosynthesis cuts growth and yield.
Sclerotinia Rot
Disease
The crown, stem or head rots in a water-soaked way and is covered in white cottony mycelium. Black sclerotia later form inside and on the surface, and the plant wilts and dies.
Anthracnose
Disease
Light brown to dark brown round lesions with sharp margins form on leaves and fruit, slightly sunken in the center. In wet weather salmon-pink slimy spore masses ooze out on the lesions.
Root-knot Nematode
Pest
The plant wilts in the daytime and does not recover with feeding or watering. Pull it up and the roots carry beaded chains of galls of varying size with few fine roots.
Gray Mold
Disease
Water-soaked brown lesions form on flowers, fruit and leaves, densely covered by a fuzzy gray mold. Fruit rots and drops, and decay continues in storage after harvest.
Verticillium Wilt
Disease
Only one side of the lower leaves yellows and wilts, and the symptom moves up the plant. Stem vascular tissue turns pale brown and the plant dies without ever growing well.
