Apart from being a tasty addition to salads, it grows easily, and really seemed to respond to a dose of chookpoo (in lieu of guana recommended in ONP notes!).

I agree that it benefits from guano. In fact, its extinction from the mainland is thought due to the loss of seabirds due to mammalian predation. They used to supply the plants with ample guano. However, it is easily grown in the garden if well-fed, and it enjoys a wash of salt water from time to time. Treat as a biennial and save seed for re-sowing (very easy to grow from seed). Susceptible to all sorts of garden pests (like aphids and white butterfly) and diseases like white rust (Albugo candida). try to eliminate shepherd's purse from the garden as this is a host for white rust. A lovely herb and makes rocket seem unpalatable in comparison. Lovely with fresh skipjack tuna.

I don't have access to guano but have found that a mix of fish frame and comfrey 'soup' and worm 'wee' sloshed around the base of my plants every few days is producing large, lush, dark green, yummy growth.