Sea Kale (Crambe maritima) is an excellent vegetable for the perennial garden. All parts are edible, but some are tastier and require more work than others. For my palate, there is a tie for best tasting part between the flower buds (like broccoli) and the blanched shoots. Shoots come early in the year, anywhere between February and April here, depending on the weather. This year, we’re getting them right on the average.
Ideally, you want to get the new shoots covered up as soon as they emerge. If you’re smarter than I am (or have fewer plants), you might mark them all the prior year so that you know where they are. If you are lazy like me, you just wait until you see them coming up and then cover them. You may pay the price in a little extra bitterness if you wait too long.
Here is what you are looking for. This one is actually several days past when I would normally want to get it covered, but it will still be OK.
Just cover the emerging shoots with something that blocks light and check on them in about two weeks. You can continue this process profitably for up to two weeks per year of age on the plant, up to four weeks. If you continue too long, you can kill the plant.
In the absence of light, the plant will produce long, pale shoots that you can use just like asparagus.
Some people use lovely ceramic forcing pots for this job. I use paint buckets and bricks. If you do use a bucket, make sure it is a dark color. I found that white buckets didn’t block enough light. I recommend drilling some holes on the north side of the bucket for ventilation.