How to Grow Platystemon Plants

Gardener's HQ Guide to Growing Creamcups

There is only one member of the hardy annual Platystemon plant genus. This is commonly referred to as Creamcups and goes by the latin name of Platystemon californicus.

The plant has green lanced shaped leaves and blooms in the summer. When it carries yellow circular flowers.

Platystemon reaches a height of about 30 cm (12 inches) when in bloom, and makes an ideal edging or border plant.

It is a relative of the Poppy family

Platystemon californicus

Cream cups
Platystemon californicus / Cream cups. Both Photographs by Tom Hilton; creative commons.

Platystemon Plant Growing and Care Guide

Common Names: Creamcups.
Family: Papaveraceae.
Life Cycle: Half hardy annual, hardy annual.
Height: 8 inches (20 cm).
Native: North America.
Growing Region: Zones 5 to 8.

Flowers: Summer.
Flower Details: Yellow, gold, white, cream. Fragrant. Single flowers. Cup-shaped. Six petals. Tufted stamens.
Foliage: Opposite. Oblong. Lanceolate.

Sow Outside: Cover seed. Before the last frost or in autumn. Spacing 6 inches (15 cm). Germination time: two to four weeks. Temperature 60°F (16°C).
Sow Inside: No.
Requirements: Full sunlight. Loam. Can survive in dry soils. Regular watering. In the spring supply a top dressing of cow manure.

How to Grow Creamcups, Platystemon Plants

The seeds of creamcups should be sown outdoors either before the last frost of spring or towards the end of autumn.

Once sown. the seeds should be covered with soil.

Alternatively buy Platystemon plants from a garden center, and put out in mid spring. Creamcups like to grow in sunny parts of the garden.

They favor a soil that has a sandy and loamy nature. Ideally the plants should be spaced at about 15 to 20 cm (6 to 8 inches) apart.

Caring for Creamcups and other Platystemon

Creamcups (Platystemon Plants) are easy to look after. They can tolerate dry conditions, but appreciate frequent watering.

If you require more Creamcups in the garden then let the plant set seed and grow in situ.

Common Questions

How many members does the Platystemon genus contain?

The Platystemon genus contains only one species, Platystemon californicus, which is also known as Creamcups.

Do Platystemon members make a good garden or landscaping plant?

Platystemon californicus can be a charming addition to wildflower meadows or informal garden borders, thanks to its cheerful, bright yellow flowers.

Which Platystemon species are most frequently grown by gardeners?

Since there's only one species in the genus, Platystemon californicus is the one you'll find in gardens.

Are Platystemon plants fragrant?

Platystemon californicus is not typically grown for its fragrance. The appeal lies more in the charming cream-yellow flowers it produces.

What is the perfect location to grow Platystemon?

For best results, plant Platystemon californicus in a sunny location with well-drained soil. It's also tolerant of drought and poor soil conditions.

Is Platystemon invasive in the USA, if so in which states?

Currently, Platystemon is not listed as an invasive species in the USA. It's native to western North America and thrives there without causing ecological issues.

How do I remove Platystemon plants from my garden?

To remove Platystemon, you can do so by carefully digging out the plant, ensuring to remove all of the root system to prevent regrowth.


The Platystemon genus, part of the Papaveraceae family, includes the annual plant commonly known as Creamcups. They are recognized for their bright yellow, poppy-like flowers.

Platystemon plants need a location with full sun and sandy, well-drained soil. Plant them in the spring, after the last frost. They're a delightful addition to wildflower meadows, rock gardens, or cottage gardens.

I hope that you enjoyed this guide on how to grow Platystemon plants. You may also enjoy the following Gardener's HQ growing guides: How to grow Plume Poppy, Allium aflatunense, Lathyrus plant, and Blue poppy plants.