Saint John’s Wort Plant

Question

How do l cut it back this spring from last year’s growth?

Answer 1

St John's Wort blooms on new wood. The flowers that appear in mid to late summer develop on the new growth that appears in the spring.
Pruning should take place in early spring, before the new growth appears.
Shrub varieties of St John's Wort should be pruned back by about 1/3 of the total height of the plant.

https://www.gardeningknowhow.com/edible/herbs/st-johns-wort/st-johns-wort-plant-care.htm