St. John’s wort
Thirty-one species of St. John’s wort
(Hypericum) are found in Florida. All
are native, and several are on state
and federal endangered plant lists. In
nature, look for St. John’s wort in sandhill
and atwood habitats, as well as on the
margins of cypress swamps and marshes.
Species vary in the appearance of their
leaves, but their reddish stems and
delightful yellow owers are constants.
Some have short needlelike leaves, while
others might look as if they belong to a
different genus entirely.
Description
St. John’s wort is an evergreen perennial
shrub known for its outstanding
ornamental features. With sturdy reddishbrown
twigs, species in this genus
can grow from 1 to 3 feet tall and have
spreads of 2 feet or more. Species found
at native nurseries typically have 1-inch
yellow owers with four or ve petals that
contrast with their dark green foliage.
Plants of most species ower in summer.
Planting
St. John’s Wort can be used a foundation
plant, along a border or edge, or in a
mass planting. Space plants from 24 to 36
inches apart.
Seeds
Native ecotype seeds are not available
commercially but may be collected from
plants when dry. Sow directly in the
garden in the fall for spring growth.
Plants
Atlantic St. John’s wort (H. tenuifolium)
is the most typical species encountered
at nurseries and plant sales. It likes dry
to moist soils and
usually doesn’t
need any pruning,
maintaining a
delightful, mounding
shape. Its summer
blooms last a
month or more. St. Andrew’s cross (H.
hypericoides), found in nature in moist
shaded areas, has an elegant, feathery
form and produces three seasons of
owers. For a showy addition to the
garden, consider Fourpetal St. John’s wort
(H. tetrapetalum), which has larger, fourpetaled
owers; and Mrytleleaf St. John’s
wort (H. myrtifolium), which has bluegreen
foliage and rich yellow owers.
Care
These hardy perennials are easy to care
for once established. A light pruning in
winter, if needed, is all established plants
require to maintain a desired shape. Give
wetland species a drink after a few days
without rain.
Site conditions
St. John’s wort does best when planted
in full sun to part-shade in sandy soils.
However, they can adapt to a variety of
other soils, including clay and loam, and
acidic and lightly alkaline soils. Plants
are not salt tolerant and are moderately
drought tolerant once established.
eep wetland species moist by adding
them to a rain garden or moist site.
Hardiness zones
Most St. John’s Wort species are suitable
for zones 8a–10b, though St. Andrew’s
cross’ southern limit is 9b.
Hypericum species are attractive
to polyester, yellow-face, large
carpenter, bumble, leafcutter,
resin and sweat bees, as well as to
Gray hairstreak butteries, whose
caterpillars feed on its seed capsules.
1–3 ft
Nectar
The St. John’s wort
that is promoted as a
supplement for use in
CAUTION
treating depression is
a non-native species.
According to Dan Austin
in his book, Florida Ethnobotany,
using native St. John’s wort can lead
to dermatitis or photosensitization due
to a hypericin compound found in the
plants.
Some species may be toxic to
livestock.
Photo by Mary Keim
Fourpetal St. John’s wort
Photo by Ron and Diane Bynum
St. Andrew’s cross
Photo by Peg Urban
Myrtleleaf St. John’s wort
Photo by Mary Keim
Atlantic St. John’s wort