Ask Mr. Smarty Plants

The Lady Bird Johnson Wildflower Center is dedicated to disseminating information about our native species and encouraging their use in their native habitats. Here is a link to our article on the reasons why natives make sense. Since St Johns Wort is a common name that covers many varieties, we can’t be positive about the precise species you are growing; Pennsylvania has sixteen native Hypericum (St. Johns Wort) varieties, with varying habitat and growth requirements. We can try to identify it if you send us a photo. If your plant is from a nursery it may be Hypericum ‘Hidcote’, a cultivar whose parents are of European origin and out of our area of expertise. Here is a link to a web page with background on Hypericum 'Hidcote'.

Some general causes for plants not to flower follow:

Too little sun; Hypericum can grow in shade, but flowers better in sunnier locations.

A variety not well-suited to your area; nurseries often get stock from far-away suppliers in different climates.

Improper fertilization; high nitrogen fertilizers can promote green over flowering growth.

Pruning at the wrong time; probably not the problem here, but some plants bloom on new growth, others on previous seasons' growth.