How to Grow Glaucium Plants in your Garden

Gardener's HQ Guide to Growing Horned Poppy and Sea Poppy

The Glaucium plant genus contains members such as the Horned poppy and Sea poppy.

As a large genus, Glaucium contains hardy annuals, biennials and perennials; though in reality most gardeners treat the plant as annuals or biennials.

Glaucium plants reach a height of 30 to 90 cm (12 to 36 inches), and have flowers reminiscent of poppies. These may be yellow, gold or orange.

Yellow horned poppy
Glaucium flamum (yellow horned poppy) by Phil Sellens.

Blackspot Hornpoppy
Blackspot Hornpoppy by Quinnanya

Glaucium Growing and Care Guide

Common Names: Horned Poppy: Yellow; Red; Orange; Bristly; Blackspot. Sea Poppy.
Family: Papaveraceae.
Life Cycle: Hardy annual. Hardy biennial. Hardy perennial commonly grown as a hardy annual by gardeners.
Height: 12 to 40 inches (30 to 100 cm).
Native: Europe, Central and Southwestern Asia, Northern Africa.
Growing Region: Zones 3 to 10.

Flowers: Summer.
Flower Details: Yellow, red, orange. Poppy-like.
Foliage: Thick, leathery leaves. Blueish-grey/white. Rippled edges.

Sow Outside: Cover seed. Annuals and perennials: following last frost or autumn; biennials: early summer. Spacing 12 to 24 inches (30 to 60 cm).
Sow Inside: Use peat pots. Germination time: two weeks to one year in the dark. Temperature 60 to 65°F (16 to 18°C). Start annuals and perennials about eight weeks in advance; start biennials in early summer. Transplant annuals and perennials outdoors a few weeks after the expected last frost. Transplant biennials outdoors in late summer or early autumn. It is usually best to sow Glaucium species directly outdoors as they do not like to be transplanted.

Requirements: Full sunlight. Good drainage. Dry soils. Can grow in salty soils.
Miscellaneous: Has ornamental horn-like seedpods that are six to twelve inches (15 to 30 cm) in length.

How to Grow Horned Poppies and other Glaucium Plants in the Garden

It is best to grow Horned poppies outdoors from seeds. Lightly cover the seeds once sown.

Sow biennial Glaucium towards the end of spring. Sow annual Glaucium plants just after the last frost. Sow perennial varieties in autumn, or just after the last frost of spring.

Plants usually take two or three weeks to germinate, though some species can take as long as a year.

If planning to grow indoors, then Glaucium seed germination will occur in the dark. Use a a temperature of 15 to 18 degrees centigrade (59 to 64°F).

Glaucium should be spaced at between 30 and 60 cm (12 to 24 inches) apart. Members of this genus, such as the Horned poppy, like to grow in sunny areas that have good drainage to produce a dry soil.

Caring for Glaucium Plants

Apart from supplying a very light fertiliser at the start of the year. You will find that Horned, Sea poppy, and other Glaucium plants will basically look after themselves.

I hope that you enjoyed this guide on how to grow Glaucium plants. You may also enjoy the following Gardener's Papaveraceae HQ growing guides: How to grow Poppy, Agapanthus plant, and Eschscholzia plants.