Hypericum, or St. John's wort, provides bright yellow flowers nestled among green foliage throughout the summer. A low-growing shrub, hypericum is suitable in borders and beds or as a single planting in the garden. The shrub only reaches about 1 foot in height, but pruning is necessary to keep it from splitting or becoming unkempt looking. Hypericum tolerates freezing weather, but extended periods of cold may kill the top of the branches. These damaged areas must be trimmed to keep the plant looking its best.
Inspect the plant in late winter or early spring before new growth appears. Locate any damaged or dead branches, which do not have leaf buds on them.
Cut the damaged branches off ¼ inch above the nearest healthy leaf bud on undamaged wood. Use a pair of pruning clippers. Cut off dead branches at the base where they join the main branch.
Check the interior of the plant for branches that are rubbing against others. Cut these out from the base.
Cut back the entire shrub to control height and shape. Trim the top off all the branches back 3 to 5 inches so they are an equal height. Make the pruning cut ¼ inch above a leaf bud. Trim the sides back the same distance to shape the bush into a full mound.