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Chaste Tree

I can think of at least three great trees I like that bloom in summer. But my favorite tree of the bunch—chaste tree (Vitex agnus-castus)—stands up to dry spells in the summer heat, grows just about anywhere, and comes with cooling blue or white flowers.

About Chaste Trees

Native to southern Europe and central Asia, chaste tree quickly grows into a multi-trunked tree about 10 to 20 feet tall and wide with a broad, spreading habit. Also known as "monk's pepper," it gets its name from the erroneous medieval belief that a potion made from it could curb libido. In reality, it doesn't, but that doesn't mean that the chaste tree doesn't have its pharmacological uses. An extract made from Vitex supposedly does a good job of alleviating premenstrual symptoms, otherwise known as PMS. But we don't recommend running right out to the yard to pick and eat your chaste berries—talk to a doctor first.

Chaste Tree's Blue Blooms

The best thing about chaste tree is the flowers, which bloom in upward-growing panicles up to a foot long. Chaste tree is one of the very few winter-hardy trees out there that sports true blue flowers (although they can also be pink, purple, or white). The one you're looking at in this article is 'Abbeville Blue,' which bears large, spectacular panicles of deep-blue flowers in summer. Other selections I like include 'Montrose Purple' (purple blooms), 'Shoal Creek' (blue-violet), and 'Silver Spires' (white). There are also smaller cultivars like 'Blue Diddley' and 'Blue Puffball' that can be grown as shrubs, while 'Cooke's Blue,' 'Cooke's Pink,' and 'Cooke's Purple' can grow to 30 feet. If you buy an unnamed chaste tree from a nursery, buy it in bloom so you can see the color of the flowers and the general shape of the plant. A good mail-order source for named selections is Forest Farm. When it's not in bloom, the chaste tree's attractions include its feathery, sage-scented, grayish-green leaflets and the brownish fruits it provides for the birds in fall.

Where to Plant a Chaste Tree

Here are some different ways to use chaste tree in the landscape:

  1. As a single specimen in the lawn
  2. In a row along a property line or a driveway
  3. Limbed-up in a border with lower plants growing beneath it
  4. As a small patio tree

How to Grow a Chaste Tree

Few trees are as easy to grow. Here's the low-down:

Light: Full sun (at least six hours a day)

Soil: Well-drained

Water: Regular moisture at first—very drought-tolerant once established

Problems: No serious pests, though it can be damaged by thrips; planting in wet areas can lead to root rot

Pruning: Not the tidiest plant in the world. Needs regular pruning to produce an attractive multi-trunked tree. Prune in winter. Clean out the entire center of the tree, removing all side branches from the main four to five trunks. Also remove messy, twiggy growth that tends to crowd the ends of the branches. As another option, cut the entire plant to the ground in winter. It will sprout in spring and bloom in summer, although later than chaste trees not pruned so severely. You can also force a second bloom in summer by removing the first flush of blooms as soon as they fade. Clean up fallen berries to avoid seedlings popping up around your yard.

Salt & wind tolerance: Good

Cold-hardiness: Usually winter-hardy in USDA Zones 6 to 9, but in Zones 5 and 6, it may die back to the ground in winter, then sprout and bloom the following summer.

Bumblebee alert: Chaste tree attracts all kinds of pollinating insects and birds. Bumblebees love this plant above all others and will even spend the night on the flowers. Keep this in mind if bees freak you out.