The Well-Tended Perennial Garden The Essential Guide to Planting and Pruning Techniques, Third Edition

Hypericum calycinum

St. John’s wort

hypericaceae

Large yellow flowers; evergreen leaves

15–18 in. high; 24 in. wide

Full sun or part shade

Blooms June–August

Zones 5–9

pruning Plants are evergreen to

semi-evergreen, depending on the

climate, although leaves are often

battered by winter weather. Plants

have a tendency to become straggly

and twiggy if neglected. They benefit

from a shearing down to 6–10 in. every

year or two in the early spring to

remove winter damage, improve

density, and keep vigorous. Removing

any crowded, weak, or dead branches

at this time is also beneficial.

other maintenance A stolonifer-

ous groundcover for dry, sunny, or

partly shaded locations. Flowering is

reduced if the shade is too great.

Plants can be invasive and may require

sections to be dug out to maintain

control every 2–3 years in the spring or

autumn. Good for bank stabilization.

Benefits from part shade and moister

conditions in southern gardens.

Iberis sempervirens

evergreen candytuft

braSSicaceae

White tufts of flowers cover entire plant;

narrow evergreen leaves

6–12 in. high; 24 in. wide

Full sun

Blooms April–May

Zones 3–9

pruning Yearly, plants should be cut

back by half after flowering to keep

them full and compact. This can be

easily accomplished with hedge shears

or by grabbing a handful of stems at a

time and cutting with hand pruners.

Such pruning takes care of deadhead-

ing at the same time. Plants quickly fill

in to form an evergreen mound that

holds through the growing season and

the winter. Some damage may occur in

severe winters. Prune off damaged

sections in the spring, if necessary.

other maintenance

Well-draining soil is essential to

survival, particularly over the winter.

A good rock garden perennial. Avoid

areas with high winds and strong

afternoon sun in the winter if consis-

tent snow cover is not reliable, as

plants will quickly desiccate. Mulch-

ing with evergreen boughs can help

alleviate the damage in such locations.

Division is seldom necessary, as plants

form a subshrub growth habit. Stems

Hypericum calycinum