Common thyme vs Lemon thyme

Most plants are lost to winter wet rather than frost: the roots rot in heavy, damp soil, so on clay plant it only in a raised spot opened up with gravel. In Central Europe the shoots can die back in prolonged hard frost without snow cover (below roughly -15 to -18 °C), especially in damp sites. It is short-lived: after 3 to 5 years it becomes woody and loose, does not reshoot reliably from old wood and needs replacing.

Its most common failure is rot: in heavy, wet soil, especially in a rainy winter, the crown and roots die, so in Central European clay gardens it is best planted in a gritty raised bed or a pot. Variegated forms (gold or white edged) are less hardy, can be cut back by windy frost without snow cover and now and then throw plain green shoots that need cutting out. It turns bare and woody within a few years unless trimmed regularly; renewing it from cuttings every 4 to 5 years is worthwhile.