St. John’s Wort (Hypericum species), with its bright yellow flowers and often semi-evergreen foliage, is a popular, low-maintenance garden plant. Proper pruning is important to ensure the plant remains healthy and thrives.
Why Pruning St. John’s Wort Matters
Pruning St. John’s Wort offers several benefits for its health and appearance. Regular trimming encourages thick, bushy growth, leading to a fuller plant. This practice also promotes more abundant flowering, as St. John’s Wort blooms on new wood. Pruning helps maintain a desirable shape and size, preventing legginess, and allows for the removal of dead, damaged, or diseased stems.
Best Times to Prune St. John’s Wort
The best time to prune St. John’s Wort depends on your goals and its growth cycle. For general shaping and maintenance, prune in late winter or early spring, before new growth emerges. This timing is ideal because the plant flowers on new growth, ensuring you do not reduce the season’s flower production. You can remove about one-third of the plant’s total height during this period.
For vigorous varieties like Hypericum calycinum, annual cutting back in spring encourages fresh growth and containment. If the plant has become leggy or sparse, a more severe rejuvenation pruning can be performed in late winter or early spring, cutting the shrub significantly, sometimes almost to the ground. This stimulates robust new growth from the base.
Deadheading spent flowers can be done after the first flush of blooms to encourage secondary flowering and maintain a tidy appearance. However, if you wish for the plant to produce berries, avoid deadheading. In areas with colder winters, wait until after the last hard frost to prune, reducing the risk of damage to new growth.
Techniques for Pruning St. John’s Wort
Use sharp, clean pruning shears or loppers for precise cuts. Sterilizing your tools, such as with a bleach and water mixture, helps prevent the spread of diseases.
When pruning, make cuts just above a leaf node or an outward-facing bud. This encourages new growth away from the plant’s center, promoting a more open and balanced shape. For general shaping, light trimming of branch tips helps maintain the plant’s form and encourages bushier growth.
To remove dead, damaged, or diseased branches, cut them back to healthy wood or the main stem. This improves air circulation and reduces pest and disease issues. For rejuvenation pruning, cut back 50% to 75% of the shrub, removing the heaviest canes to the ground to encourage new shoots.
After Pruning Care
After pruning, ensure St. John’s Wort receives sufficient moisture to help it recover and grow. Watering thoroughly helps reduce stress and supports the plant’s recovery.
While low-maintenance, a balanced fertilizer can be applied in early spring to support new growth. Monitor the plant in the weeks following pruning for signs of new shoots and overall vigor.