Most seed package instructions tell you to plant arugula, cilantro, and Asian greens (like bok choy, gailan, mizuna, tatsoi etc.) in the spring and again in late summer or fall. Starts, or small plants, are also offered to you in the spring.
But wait! Those seeds sown in spring and the plants you buy are pretty much guaranteed to “bolt.” This term refers to the plant shooting up and making seed rather than the leaves you want. They dislike heat and so this happens as the temperature rises. Plants do that in order to survive at all costs.
To avoid bolting, plant these seeds after the summer solstice – ideally in August or early September, when the sun is going back the other way. You are much more likely to receive a bountiful crop, and the plants may overwinter and keep giving you more leaves until it goes to seed in May or June! The same applies to the rest of the plants described above and possibly including spinach, which also prefers cool weather.
Submitted by: Sharon Hanna, Friend of UBC Botanical Garden (FOG)