Cosmos bipinnatus Kiiro | Pastel Yellow Cosmos | Seeds

Cosmos Kiiro produces delicate pastel-yellow flowers with a distinctive peach-coloured reverse to the petals. As the flowers open and move in the light, these warmer undertones give each bloom a soft, changing appearance.

Tall, branching plants with finely divided foliage bring an airy feel to borders and cutting gardens. Their gentle colouring combines beautifully with white, cream, blush pink, lavender and soft apricot flowers.

Plant Information

Botanical name: Cosmos bipinnatus
Common name: Cosmos
Variety: Kiiro
Family: Asteraceae
Plant type: Annual
Plant habit: Tall, upright and branching
Flower type: Single, daisy-like
Flower colour: Pastel yellow with peach-toned petal reverses
Height: Approximately 90–120 cm
Plant spacing: Approximately 30–45 cm
Days to Bloom: Allow approximately 80–90 days from sowing under favourable growing conditions
Position: Full sun
Soil: Moderately fertile and well drained
Flowering: Summer into autumn, until frost
Uses: Cut flowers, mixed borders, cottage gardens and meadow-style planting

Flowering time varies with sowing date, temperature and daylight conditions.

Pastel Yellow with a Peach-Toned Reverse

Kiiro’s charm lies in its subtle colour combination. The open flowers show a soft yellow face, while the peach-tinted backs of the petals add warmth, particularly in buds and partly opened flowers. This distinctive colouring is also noted in the supplier’s variety description. 

Grow it among ornamental grasses for a natural planting, or combine it with other pastel flowers for romantic summer bouquets. The finely divided foliage adds softness even before flowering begins.

Sowing & Germination

Sowing indoors: Approximately 4–6 weeks before the last expected frost
Direct sowing: After the last frost, once the soil has warmed
Sowing depth: Approximately 0.3–0.5 cm; cover lightly
Germination temperature: Approximately 20–21°C
Germination time: Usually 7–14 days under suitable conditions
Planting outdoors: After all risk of frost has passed

Sow into a fine, moist seed-starting mix and cover lightly with substrate. Keep evenly moist during germination, avoiding waterlogging.

After emergence, provide plenty of light. Move seedlings into larger cells or pots when needed, before the roots become crowded.

Harden plants off gradually before planting outdoors. Cosmos is frost tender, so wait until the weather is reliably warm.

For direct sowing, prepare a fine seedbed in a sunny position. Water gently and thin seedlings to their final spacing once established.

Growing Conditions & Care

Choose a sunny, open position with well-drained soil. Avoid overly rich soil and heavy nitrogen feeding, which can encourage abundant foliage at the expense of flowers.

Water regularly while plants establish, then during prolonged dry periods. Allow excess water to drain freely.

Pinch out the growing tip when plants are approximately 20–30 cm tall to encourage branching and more flowering stems. Pinching may delay the first flowers slightly.

Allow approximately 30–45 cm between plants so the branches have room to develop. Tall plants may need support netting or stakes in exposed locations.

Long-Lasting Summer Colour

Remove faded flowers regularly to encourage further flowering. Picking stems for bouquets also helps keep the plants productive.

Kiiro is a lovely choice for the middle or back of a border, where its tall stems can rise above lower flowers. Its open blooms also provide accessible feeding opportunities for visiting pollinators.

Cutting for Bouquets

Cut when the petals are beginning to open, choosing firm stems rather than very soft, immature growth.

Harvest during the cooler part of the day, remove foliage that would sit below the waterline and place stems promptly into clean water.

The pastel-yellow flowers and peach undertones add lightness to loose garden bouquets, wedding arrangements and seasonal floral designs.