Here's a trick question: Name a small tree with showy blue flowers. If you're stumped, it's all right. Very few trees qualify. Texas mountain laurel (Sophora secundiflora) is one, but its range is limited due to lack of cold hardiness. Here's the better choice for most of us in the South—chaste tree. It grows practically everywhere.
Native to southern Europe and central Asia, chaste tree (Vitex agnus-castus) got its name in medieval times. Substances in its seeds (called "monk's pepper") supposedly suppressed the libidos of novice monks.
In most of the South, chaste tree grows 10 to 15 feet tall and features multiple gnarly trunks with blocky bark reminiscent of alligator hide. Its aromatic leaves, divided into five to seven narrow leaflets, bear more than a passing resemblance to marijuana, so label your plant lest you receive an unwelcome visit from the feds.
In early summer, branched spikes (panicles) of blooms up to a foot long crown the plant. Blue and violet are the most common colors, but you can also find pink and white ones. Add chaste tree to a lawn, patio, or spot near the street. Or limb it up in a border and put lower-growing plants beneath it.
Chaste tree does need regular pruning to stay tidy. Cut off the first spent flowers in summer to get a second crop. In winter, clean out the center of the tree, removing all side branches and twiggy growth from the main four or five trunks. Or cut the whole tree to the ground. It will grow back quickly and bloom by summer.
Plant It Now!
Name: Chaste Tree
Light: Full Sun
Soil: Well Drained
Hardiness: USDA Zones 6 through 10
Our Favorite Chaste Trees: 'Abbeville Blue' (large, deep blue spikes), 'Montrose Purple' (violet), 'Shoal Creek' (blue-violet), 'Salinas Pink' (pink), and 'Silver Spire' (white)
Bring It Home: If you can't find the chaste tree you want at your local garden center, visit a good mail-order source, including forestfarm.com, nichegardens.com, and woodlanders.net.