Thai Double Blue

Thai Double Blue is a Thai selection of butterfly pea grown for pigment as much as for looks, and there is one thing to know before sowing it: it is not a uniformly double strain. The catalog description Baker Creek uses, reproduced by Rush Creek Growers and by the Freeport Library's gardening guide, calls it a single- and double-flowered type found in Thailand, so a packet yields a mix of ruffled multi-petalled blooms and plain single pea-flowers. Both carry the same anthocyanins, so both steep the deep indigo tea that flips to pink the instant lemon juice hits it, and both work as natural dye for rice, drinks and desserts. In Thailand the blooms are used exactly that way, colouring teas, rice and sweets. As a legume it fixes its own nitrogen and asks very little of the soil, but it is frost-tender and only behaves as a perennial where winters stay warm.