Hypericum (Hypericum frondosum) is also sometimes referred to as golden St. John's wort, St. John's wort, and blueleaf St. John's wort. It is a perennial-growing, semi-woody, low-to-medium-growing shrub, depending on the variety. As a native plant to the southeastern United States, it is found growing in open meadows and in near forested habitats. Although hypericum has a tendency to become invasive, it is a hardy, fast-growing plant that requires little care once established.
Purchase healthy hypericum plants either in 3-inch, 4-inch or 6-inch-wide pots. You can also purchase them in one-gallon pots. Avoid larger-sized pots since the plants may be root bound.
Locate a site in your garden where you want to plant the hypercium. Although hypericum can tolerate some light shade in cooler Northern climates it grows best in full sun. In hotter Southern climates, you should choose a location that offers partial shade during the hottest part of the day, usually afternoons.
Soak each of the hypericums in a bucket or tub that is about 1/2 full. This helps make transplanting easier and plumps up the roots in case they have been overly dried out.
Dig up the soil in the area you have selected for planting the hypericum. Use a spade, fork or rototiller if you're planting a large area. The soil should be well-aerated and loose.
Dig planting holes for each hypericum, spacing each hole about 10 to 16 inches apart, depending on the variety you're planting. Make each hole about twice the width and about the same depth of each planting pot. Measure 1 tbsp of a 10-10-10 or similar all-purpose granular fertiliser. Mix the fertiliser into the soil in the bottom of the planting hole. Do this for all the planting holes.
Lay a hypericum on its side, using care not to break off any of the foliage. Strike along the bottom of the pot using a rubber mallet, hammer or a block of wood. Once the pot begins to loosen, wiggle the plant free from the pot. If the roots appear overly bound or otherwise matted, make two to three vertical cuts across the root system using a sharp knife.
Plant the hypericum in the planting hole so it is level with the adjacent garden soil. You may need to remove the plant from its planting hole to scoop in a few trowels of soil, then readjust the plant in its hole.
Fill each hole with water, letting it totally drain back before proceeding. Fill the planting hole full with soil, using your hands or a trowel to push the soil around the roots of the hypericum.
Fertilise hypericum every spring with a water-soluble fertiliser, such as 15-15-15 or similar. Read the directions as specified on the product label so you'll know how much to use per gallon of water. Hypericum is hardy in USDA zones 5 to 8, according to Floridata.com. To prevent some varieties of hypericum from becoming leggy and unkempt, you may need to prune about 3 to 4 inches off the hypericums every spring, before new growth appears.