The blooming season for St. John’s Wort starts in mid-summer and typically lasts for up to 6 weeks. After that, the shrub will produce bright red berries that are just as decorative as the flowers and are a good winter food source for wildlife in the garden. There are a few steps that can be taken if your St. John’s Wort fails to produce flowers or berries as robustly as it used to.
Common Reasons Why St. John’s Wort Isn’t Blooming
Proper pruning, lack of enough sunlight, and the need for supplemental fertilizer are the three most common reasons that St. John’s Wort does not bloom or fruit well. St. John’s Wort blooms on new wood and responds well to pruning early in the spring. As surrounding trees and shrubs grow and mature, they may create too much shade for the St. John’s Wort to thrive. The branches and foliage may start to get spindly and sparse. If this happens, consider transplanting the shrubs to a brighter location or cutting back the surrounding plants.
Pruning St. John’s Wort To Help It Bloom
Since St. John’s Wort blooms on new growth every year, the plants will only flower at the branch tips if it is not pruned back every year. Cutting back to the woody growth early in the spring will help St. John’s Wort to remain compact and dense. Shrubs that have been neglected for a few seasons are easily rejuvenated with a hard cut back into the woody growth. New shoots will quickly develop, and if rejuvenation is done early in the spring, blooming will not be sacrificed.
Fertilizing St. John’s Wort To Help It Bloom
An annual feeding with a fertilizer formulated for Roses or other blooming shrubs may help St. John’s Wort to begin blooming again. A granular, slow-release food that has higher P and K numbers will help to support flowering and fruiting. Look for NPK ratios close to 6-12-6 or 0-10-10, which will encourage flower production and not excessive foliage growth. Mulching on an annual basis with organic compost will also provide nutrients for the soil as it breaks down. The nutrient content is not easy to control in compost, but it is a gentler and more consistent way to feed the soil.
Getting St. John's Wort To Produce More Blooms
St. John’s Wort is a shrub that also forms decorative berries after blooming has finished. If the flowers are deadheaded, then they are not able to set seed and fruit. Extra watering may be necessary during either the flowering or fruiting period if the weather is excessively hot or dry. A bad blooming period will result in less fruit forming. If the conditions are extremely hot and dry during fruit formation, the berries could dry up and fall off without supplemental water.
Why St. John’s Wort Isn’t Blooming
- Too little direct sunlight
- Pruned poorly or failing to be pruned on a regular basis
- Soil does not have enough Phosphorus, or too much Nitrogen has been applied.
Author Robbin Small - Published 8-15-2022