Use every time you are preparing the soil for planting. Sprinkle evenly over the soil and mix in well. Water well after planting out, especially in dry weather.
During the growing season sprinkle evenly over the soil around established plants. Gently work it into the soil surface with a hand fork without disturbing the roots and water in thoroughly.
For established plants, in borders and containers apply at the start of the season and reapply 1-2 times to stimulate flowering, fruit formation or fruit ripening when plants are actively growing. Sprinkle around plants, fork in and water in well.