Greek oregano is the intensely aromatic subspecies used in Mediterranean cooking — far more pungent than common oregano. The difference is the density of essential oils, which concentrates in full sun and lean soil. Rich, moist growing conditions produce lush but flavourless leaves. Harvest just before and during flowering, when oil content is highest.
Reliably perennial in Zone 5–10; cut back hard in early spring to 2–3 inches above the base to encourage fresh growth. Divide every 3–4 years when the centre becomes woody. Dry by hanging bundles upside-down — oregano dries better than almost any other herb.
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.
Spider Mites
Tetranychus urticae →Fine stippling or bronzing on leaves, faint webbing on undersides, foliage drying out during hot, dry weather.
Spray foliage with a strong jet of water to dislodge mites. Apply insecticidal soap or horticultural oil to leaf undersides; repeat every 5–7 days as needed.