[Overview]
An annual or perennial.
The stem is square in cross section.
Leaves are simple and opposite, with entire or toothed margins.
Verticillasters at the stem tips bear densely packed flowers.
The inflorescence has leaf-like bracts.
The corolla is divided into two lips, upper and lower, and there are 2 stamens that protrude far out.
The fruit is a schizocarp.
[Cultivation]
Propagate by division, from seed, or by shoot cuttings.
It prefers sunny, well-drained, well-ventilated, slightly moist soil.
It is very cold hardy.
For potted plants, water when the soil surface dries; for plants in the ground, rainfall is sufficient.
In spring and autumn, apply slow-release fertilizer placed on the soil.
Pests and diseases include powdery mildew, gray mold and aphids.
