When should I harvest thyme for the strongest flavour and can I take repeat cuttings?

Thyme aroma (its oil content) is strongest just before or as it begins to flower, so for the best flavour cut it at that pre-flowering to early-flowering stage. Harvest in the morning after dew dries, when oils are concentrated. Because thyme is a perennial, you can take repeat cuttings through the season: snip the top few centimetres of soft stem, leaving enough green growth on the plant so it can regrow, and avoid cutting hard into old woody base. Done this way it branches and gives several flushes. Do not strip the plant bare or cut into bare wood, as thyme is slow to recover from old stems. Pinching off flower buds keeps it producing tender leaf longer, though letting it flower briefly is fine and bees like it. For drying, the pre-flowering cut also gives the best dried flavour. Keep the plant in full sun and well drained soil, and trim it regularly so it stays compact rather than going leggy. Treat each cutting as a light prune that keeps the plant productive, and you will get repeat harvests from the same plants for a few years.