Shrubby St. John's-wort

Size, growth and what to expect

Shrubby St. John's-wort grows slowly, 6 inches to a foot a year in our growth estimator. It makes a dense, rounded shrub usually 3 to 4 feet tall and as wide, at most 6 feet, and the older bark peels away to show orange-brown beneath. Its narrow, dark green leaves run 1 to 3 inches long. A shrub can be short-lived, but it seeds itself freely, and seedlings may flower in their third year.

Golden flowers up to an inch across open from June to August, each with a brush of 150 to 500 stamens. A flower lasts one day, but a shrub stays in bloom for about three weeks. The capsules ripen and split in fall and hang on through winter.

It grows wild from New York and southern Ontario west to Michigan, Wisconsin and Iowa, and south to Georgia, Louisiana and Oklahoma. Its home is rocky slopes, dry wooded hillsides, old fields and gravel bars along streams. In New England it is not native and grows only in disturbed ground.

How to grow Shrubby St. John's-wort

Shrubby St. John's-wort flowers best in full sun and takes part shade. It grows in sand, loam or clay, acid or limy, as long as the soil drains, and once rooted it rides out drought. It stands occasional flooding but can be short-lived where winters stay wet. Set plants 3 feet apart and keep them 2 feet from a wall. At its size it can go within 15 feet of overhead wires.

Saplings ship bare-root or potted. Plant them in a hole wider than the roots and no deeper. Set the crown at the soil line, put the native soil back in, and keep the mulch clear of the stems. Gather the capsules as they turn brown and split in fall. Sow the seed outdoors in fall, pressed onto damp soil without covering it. For spring, hold the seed damp in the refrigerator for 3 to 4 weeks first. Kept warm indoors, seedlings come up in two to three weeks.

Water it every day for the first two weeks after planting, then every two to three days until week 12. After that, water weekly through the first two summers, then only in long droughts. It flowers on new growth, so prune it, if needed, in early spring. Deer and rabbits seldom browse it.

Each flower carries both male and female parts, so there are no male and female plants to pair. Bumble bees and other bees gather its abundant pollen, since the flowers make no nectar. It has no serious pests, though root rot and wilt can strike in hot, humid summers. Eating the plant or getting its sap on the skin can poison some people, making their skin sensitive to sunlight.