Verbena is commonly referred to as a tree, but is actually classified botanically as a type of herb. There are a great number of varietals of verbena, often also referred to by its ancient name "Vervain", one of the most popular of which is the fragrant lemon verbena. Other varietals are known for their red or white blossoms, and still others for their many shaded blossoms and spiky leaves. Growing and caring for a verbena tree is relatively easy under the proper growing conditions.
Locate a sunny patch of soil with very little exposure to shade. Verbena requires nearly full sun to avoid falling victim to mildewing or mold. With the right location, plant care is nothing short of a breeze. The soil should have adequate drainage and be well balanced and neutral with plenty of mulch.
Dig the new root ball a hole that is as deep and wide as twice the size of the root ball itself. Be sure to line the new planting with plenty of mulch which will inhibit the growth of weeds. Water and more mulch around the base of the new root ball completes the planting.
Daily watering is essential to allow the new verbena tree's roots to take hold effectively. Once this has occurred verbena requires only weekly watering and infrequent fertilization to thrive. Pruning of declining or dead blossoms during the summer blooming months will encourage re-blooming and re-growth, and one fall pruning to remove diseased, damaged, or declining growth will ensure a healthy tree when the new blooming season returns. Verbena is also susceptible to the inroads of a particular type of brown caterpillar known as a "woolly", and removal requires hand picking off the caterpillars and treating the trees with a pesticide spray.