Perennial, or ‘wild’, rocket (Diplotaxis tenuifolia) is very popular now and increasingly likely to appear in your salad. For good reason – the flavour is nice and sharp and doesn’t get bitter, even in the older leaves. The leaves are more slender and deeply serrated than annual rocket, and don’t go limp soon after picking. Makes good pesto and in the second year is conveniently ready to harvest at the same time as wild garlic. Can harvest as cut and come again... and again the following year.
Sow enough plants so you will be able to pick sparingly and regularly from each one without weakening individual plants. Seeds are quite small. I plant around 4 seeds per module in a tray and then plant outside in their final home a few weeks later. The long summer days will trigger flowering. You can pick off the flowering stems to encourage more leafy growth or let them flower and collect the seed in Autumn.