English thyme is the foundational culinary thyme: the aromatic, slightly camphorous herb of roasting, soups and bouquet garni. It thrives on neglect in lean, well-drained soil and full sun; overwatering or rich soil produces rank, flavourless growth. The tiny pink flowers in early summer draw bees and are edible.
Plant it 12 inches apart in spring, in sandy or gritty ground, or in a pot with extra grit. Harvest sprigs any time, but the oils are strongest just before it flowers; cut whole stems and strip the leaves, then dry the surplus, which thyme does better than most herbs. Cut the plant back by a third after flowering to keep it compact and productive.
Plants turn woody after three or four years and should be replaced with rooted cuttings or a layered stem. In zone 4 and 5 a loose winter mulch of evergreen boughs helps it through, and the real killer is winter wet rather than cold, so site it on a slope or in a raised bed. Deer and rabbits leave it alone. It is a Mediterranean native and the species behind most of the named thymes.
Root rot
Plants wilt, yellow, and stunt even in moist soil; lower stems and roots turn brown, soft, and mushy and the plant may collapse. Most common in heavy, wet, or poorly drained ground.
Improve drainage and stop overwatering, and never plant too deep. Lift and destroy badly affected plants along with the soil around the roots. Grow in raised or free-draining beds to prevent it returning.
Powdery mildew
White or grey powdery coating on leaves - usually starting on older growth in humid conditions or when nights cool.
Improve air circulation by thinning plants. Apply neem oil or potassium bicarbonate spray at first sign. Avoid overhead watering.
Botrytis (grey mould)
Grey fuzzy mould on petals and stems, worst in cool wet conditions.
Remove affected parts immediately. Improve air circulation. Avoid overhead watering. Apply copper fungicide if severe.