Sweet lavender, also known by its Latin name Lavandula heterophylla, is an herbaceous perennial valued for its fragrant flowers and ease of care. The plant flowers during late spring, producing numerous dusky purple flowers on tall spikes that rise above the short clump of foliage. Sweet lavender flowers are commonly harvested and used for homemade potpourri, sachets and flower arrangements. Native to Europe, sweet lavender thrives in USDA hardiness zones 5 through 9, making it a popular ornamental for gardens in temperate regions of the country.
Plant sweet lavender in a location that receives full sunlight throughout the day and consists of extremely well-drained soil. It cannot tolerate wet feet and good drainage is vital to the plant's success. Space sweet lavender plants at least 18 inches apart.
Apply a 1- to 2-inch layer of gravel mulch over the ground surrounding sweet lavender plants to increase moisture retention, deter weeds and insulate the soil. Provide at least 3 inches of space between the plant's base and the mulch to allow enough air circulation.
Water sweet lavender plants about once per week during spring, summer and fall to prevent the soil from drying out completely. Reduce the frequency of watering to once every two weeks during winter, when the plant is no longer growing actively.
Fertilize twice per year, once during early spring and again in mid-summer, by side-dressing with organic compost. Spread a 2-inch layer of compost over the soil surrounding the plant, and it will slowly release nutrients as it decomposes. Do not allow the compost to touch any the plant, as this may promote rotting and disease.
Prune sweet lavender plants after flowering ends to increase their overall health and visual appeal. Use pruning shears to cut back overgrown, bare, damaged and diseased branches. Do not remove more than 1/3 of growth during any pruning session, as the plants may not recover.