Japanese Indigo (Persicaria tinctoria)
Japanese Indigo is an annual plant yielding pure blue.
Sow seeds indoors in March/April. Sow thinly and lightly cover with a layer of compost.
Seeds can be sown in plug trays with a few seeds per cell or in an open flat seed tray. Germination is increased by warm temperatures – a heat mat is ideal. My preference is plug trays as the young seedlings are not tolerant of root disturbance which is more likely to occur when teasing seedlings apart in a flat seed tray.
Japanese Indigo is a heavy nitrogen feeder, therefore water with a spray mister weekly with a diluted nitrogen feed when the first true leaves appear – to get your plants off to a healthy start.
Before transplanting to the garden (about June time) ensure the soil is well prepared by forking it deeply with a healthy amount of organic matter, then space about 12 inches apart. It requires good drainage and needs to be kept moist by regular watering in the drier weather.
Feed the plants about every two weeks with a diluted nitrogen feed – particularly in the first few weeks of the growing season, which will greatly assist the leaf production.
Harvest leaves from mid-summer until autumn. The leaves are ready when you pinch them and see a dark blue stain.
It is important to sow fresh seeds harvested from the previous season as germination rates drop significantly in seeds over a year old.
0.5g – 25 seeds £3.25