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Mertensia maritima, the oyster plant

Oyster plant

Mertensia maritima, also called oyster plant or oysterleaf, is a surprising herb.

Oyster plant key facts

Name – Mertensia maritima
Family – Boraginaceae
Foliage – evergreen

Type – herbs and spices, perennial
Height – 1 ½ feet (15 cm)

Exposure: part sun  –  Soil: well-drained  –  Flowering: summer

The oyster plant has a quite uncanny taste for a member of the plant kingdom.

How to sow Mertensia maritima

Sowing the plant from seed is certainly the best way to grow mertensia.

That way, you’ll encourage the oyster plant to settle into its growing environment, and will ensure it develops well.

This plant, which is quite fragile, doesn’t much like being moved around or transplanted.

  • Mertensia is preferably sown in spring or fall, but you’ve got to ascertain that it won’t freeze.
  • Mertensia really hates places that are too hot and too sunny.
  • It appreciates well drained soil and detests moisture.

It’s also possible to prepare seedlings in a sheltered spot a bit earlier, and then carefully transplant to the ground in spring.

Planting Mertensia maritima

If you were able to prepare seedlings in a covered spot, or if you’ve purchased your plants in a store, it’s best to wait for spring to transplant your mertensia.

Mertensia maritima plantingYou’ll be able to plant your mertensia directly in the ground or, better still, in pots: growing mertensia in pots is highly recommended to protect it from snails.

  • Avoid soils that are too compact and too heavy.
  • Favor part sun instead of spots that would get too hot.
  • Water when the soil is dry, but don’t overdo it because mertensia hates moisture just as much as it does dry spells.

Growing it in pots has 2 key advantages

  • If you elevate your pots by an inch (a couple centimeters) or so, snails won’t be able to climb on it – and if they could, they would, since they really love the plant!
  • Mertensia is self-sowing, and growing it in containers will help mark out its growing space: when it pleases itself somewhere, it tends to get quite invasive.

Caring for Mertensia maritima

The oyster plant is rather fragile, and you’ll have to pay attention to its needs if you hope to see it grow to the point of harvesting its delicious herb leaves.

Care it needs is:

  • Mertensia maritima careCut the stems back to half their length regularly, this gives the plant vigor and will fortify it.
  • Eliminate flowers as you see them opening up, they’re not really appealing and they absorb a lot of the plant’s energy, diverting it from the leaves which are the highlight of this special plant.
  • Water in case of prolonged dry spells and heat waves.

It’s also a good idea to mulch the base of the plant in summer, this helps keep the ground cool.

Harvesting mertensia maritima leaves

The leaves can be harvested when needed from spring to fall.

  • A morning harvest will taste more fragrant than harvests that are picked later during the day.
  • Never collect more than half the leaves, because the plant needs them to keep growing.

Mertensia, snails and slugs

These 2 parasites, snails and slugs, are the 2 most devastating pests for Mertensia maritima.

Indeed, they simply crave its leaves when they can access them, and will mow down an entire plant in days.

It’s preferable to protect your Mertensia maritima from snails and slugs with a protective net or mulch prepared from sharp, dry needle-like material.

Good to know about Mertensia maritima

Mertensia maritima, oyster plantThis plant is often used in gastronomy by connoisseurs, especially rated chefs that love pairing it with fish.

It’s delicious both raw and cooked.

A few synonyms to impress your audience…

Mertensia maritima was and is known under different names. The most common name is “oyster plant”, but it’s also called “oyster leaf”, sea mertensia, and sea bluebells.

Virginia lungwort is a cousin variety, Mertensia virginica.

Smart tip about Mertensia, the oyster plant

Offer your guests a mertensia leaf when you pass around glasses of Champagne: they’ll be amazed and impressed with this surprising yet delicious pairing!
(Only drink alcohol in moderate amounts…)

Images: 123RF: Joe Photo, CC BY 2.0: K M, CC BY-SA 2.0: Mike Clark, Stéfan; Pixabay: Myriam Zilles, Rebeck96
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  • Virginia Lee Blood wrote on 30 August 2023 at 0 h 36 min

    I have a very large pot for my oyster leaf. I mixed Perlite with potting soil; I potted my plant. It seemed to do so-so sitting in an eastern window. Sadly, the leaves slipped away one by one. So, are the roots dead?? How much sun does the plant want and need? I love these leaves!! I have a thermometer in the dirt to make sure the plant doesn’t get overheated. What else can I do??

  • Jana Mariposa wrote on 21 July 2023 at 21 h 42 min

    Do you sell Mertensia maritima seeds? I would like some, if so.

    • Gaspard wrote on 22 July 2023 at 1 h 44 min

      Hi Jana, no, we don’t sell any seeds. Try to look for it on an online store, because not many nurseries are going to have them. Or, better yet, call up your local nursery and see if they can order/get some; that way, you’ll build up a local relationship and they might also like discovering a new plant for their other customers!