St. John’s Wort is a perfect example of why common names need to be verified with a botanic name. At your local nursery you will most likely find a broad-leaved variety of Hypericum labeled St. John’s Wort. The botanic name for this creeping ground cover is Hypericum calycinum and it has no herbal use at all. Since there are about 370 different species of Hypericums it is vital to make sure your plant is labeled Hypericum perforatum if you are seeking the herbal St. John’s Wort. One key to look for, besides the proper botanic name, is the perforation in the leaf. Holding the leaf to the light shows little translucent dots around the edge of the leaf (thus the species name perforatum).
In some areas St. John’s Wort may be invasive. We have not seen that here. In fact, with our dry hot summers and multitudes of gophers, we have trouble keeping it alive which is a shame because it makes a great beneficial insect attractor.
This patch of St. John’s Wort is over 15 years but because our climate is very dry it takes it a long time to spread. This section is about four feet by three feet. It is on a drip which also keeps it from reaching further.
Before you use an herb medicinally, you should consult a qualified practitioner. Large quantities ingested by livestock or horses is poisonous.
This plant is sometimes available in a plug tray. These trays hold 128 of all the same plant. They are a great low cost way to fill a lot of space. Each cell is 3/4 of inch by an inch. Check here to see if St. John’s Wort Plug Trays are available.