How and When to Harvest Green Seaweeds

Green seaweeds are wonderful added to salads, pizza or to roast in the oven (see my Foraging book and Seaweed book for more ideas and recipes). Like all seaweeds they need careful harvesting to ensure that they continue to grow and flourish.

Here I introduce 3 green seaweeds: how and when to sustainably harvest.

I highly recommend using scissors to harvest seaweeds, as cutting the weed makes it easier to leave the holdfast (seaweed's equivalent of a root) behind, enabling the weed to continue to live. Below are specific guidelines for three green seaweeds that I regularly teach.

Sea Lettuce (Ulva lactuca)

Sea Lettuce starts to grow well from Spring to Summer. Like our leafy land greens, it responds well to light and warmth. They are several types of Sea lettuce, each ones grows to a different length. Make sure the seaweed is attached and cut the upper two thirds, leaving the lower third intact. Harvest between spring and early summer. The plants will be larger towards summer and the vitamin C with be higher then too.

Gutweed/Sea Greens (Ulva intestinalis)

Gutweed also has many different types but is categorised as long, single, unbranched strands, compared to the sheets of sea lettuce. Harvest at a similar time to sea lettuce, and cut in small patches where it grows profusely.

Remember to pick in rocky pools rather than sandy beaches. As each of those strands is actually a tube and if sand gets in the tubes it won't get out easily!

Velvet Horn/Green Sponge Fingers (Codium fragile)

There are two sub-species of Velvet horn, and I rarely come across it in vast amounts. Never take more than half of any one plant, and harvest scantily, leaving most of plant intact. Harvest between the Spring and Autumn.

Find out about this and so much more on my regular seaweed foraging courses.