Sub-shrub of the Lamiaceae family, Thymus x citriodorus is a horticultural hybrid, generally considered to result from the cross between Thymus vulgaris and Thymus pulegioides, known and cultivated since at least the 17th century. The cultivar 'Aureus' is selected for its entirely or largely golden foliage, which is its main attraction.
It forms a bushy, dense, and rounded clump, 15 to 25 cm in height, with woody stems at the base and tight branching. The leaves are small, oval, bright golden yellow to yellow-green depending on the season and exposure, with sometimes a slight variation in shade between the center and the periphery of the clump. The scent, distinctly lemony, is one of the most consistent features of the hybrid and is released as soon as the foliage is slightly crushed.
The flowers are small, pale lilac pink, grouped in terminal whorls. In cultivation, flowering generally occurs in June-July. It remains discreet compared to the effect of the foliage, which is the main interest of this cultivar throughout the growing season.
It requires full sun to maintain the intensity of its foliage color — in the shade, the foliage turns noticeably green. The soil must be well-drained, poor to moderately fertile. A light pruning after flowering helps maintain a compact shape. Suitable for rock gardens, dry borders, and aromatic plant associations.