Lemon verbena (Aloysia triphylla) is a perennial growing up to 5 feet tall and should be spaced nearly 2 feet apart when planting to ensure adequate room for spreading growth. This lemon-scented herb is used in herb pillows, drinks, and jellies according to the North Carolina State University Extension. It is a native to Chile and Argentina, making it sensitive to colder climates. It grows best in USDA zones 9 to 10 in the United States. It is susceptible to drying soil, so a strict watering cycle should be followed, along with regular close inspection.
Place a sponge in the bottom of the planter when transplanting lemon verbena. A sponge will prevent the soil from washing out through the drain holes of the planter and retains moisture in the soil.
Monitor the soil closely and water when the top 1 inch of soil has become dry. Prevent the soil from becoming dry any deeper into the planter.
Pour water into the planter, covering the entire soil surface. Continue to water until the excess drains from the bottom of the planter.
Water the lemon verbena twice weekly or more often if the soil becomes dry. It will need more water than the other herbs in your garden.