Leaves and flowers
The gray-blue leaves are thick, crispy and salty. The plant does not lose its leaves in the wintertime. From June until August, the plant grows flowers that are initially red and after a while turn blue. The flowers are also edible.
Properties
Medicinally the plant is used to treat colds, coughs and sore throats, and has anti-inflammatory properties.
How to grow
Oyster leaf is not the easiest to grow. Furthermore, snails love the plant so keep an eye out.
To grow Oyster leaf from seed you either sow the seeds directly into the soil from October until February; or in a controlled greenhouse environment in March/April. In the latter case you sow the seeds on some soil (cover with a thin layer of soil) and leave them in the greenhouse for 2-3 weeks. Thereafter you leave them in the fridge for 5-6 weeks (cold stratification technique). Germination will follow after. The seeds require this boost of cold to germinate. The seeds germinate rather irregularly, so be patient.
This plant does not like root disturbances, so do not wait too long with planting them at their desired location. This plant can withstand very cold temperatures and strong winds and does not require many nutrients to grow. Even though the plant is very winter hardy, it is susceptible to root rot. A well draining soil is a must.
Sources
https://en.wikipedia.org/wiki/Mertensia_maritima
https://www.magicgardenseeds.com/The-Good-To-Know/Oyster-Leaf-(Mertensia-maritima)-A.MER01-