Chaste Tree

Vitex agnus-castus

A sophisticated yet often overlooked Mediterranean shrub, the Chaste tree, or Vitex bush, adds a touch of late-summer elegance to the autumn garden. This impressive shrub can reach heights of up to 8 feet (2.4 meters) in ten years.

With its refined appearance, the Chaste tree stands out from similar plants like Buddleia, showcasing soft, aromatic palmate leaves and long clusters of delicate mauve flowers.

As a deciduous shrub, it becomes a haven for pollinators, drawing in bees and butterflies for weeks during early autumn. Its beauty and ecological benefits make it a remarkable addition to any garden landscape.

Eight year-old Vitex agnus-castus coming
into leaf in my Sussex garden. (May)

ABOVE I grow my Vitex (Chaste tree) in a raised bed, along with other Mediterranean plants, including lavender, artemisia, salvia and sedums. It naturally suits a Mediterranean style garden, but has potential in many planting schemes. It can be grown in any situation where lavender will thrive. Just ensure the soil is free-draining, and it has some protection from the worst of the winter cold.

Vitex is an adaptable shrub, holding on to its foliage throughout winters in warmer climates. In the UK it is deciduous, and also rather late into leaf, with new foliage only emerging in late April. The canopy does not become really dense until June. This has two benefits for UK gardeners. Firstly, its foliage is more likely to avoid frost damage. Secondly, a wide range of spring plants can be grown beneath it, as they will gain plenty of early season light.

Vitex plants are rarely seen in UK garden centres, but can be found in specialist nurseries. Fortunately, they are easy to purchase online. I forget where I got my plant (Beth Chatto, perhaps?) but I kept it for several years, languishing in its original five litre pot, where it survived several winters. I finally got round to planting it five years ago, and despite having become pot-bound and nutrient starved, it grew away perfectly well, as you can see in the photos in this article.

If I had left it to its own devices, my plant would have been clothed to the ground in foliage, but each year I prune back the lower branches to lift the crown. My plan is for it to eventually become a ten foot (3m) dome-topped small tree with clear stems on the lower third. So far this plan appears to be on course, with it now producing a spectacular autumn display above the 4ft hedge that runs across my garden (below).

The same shrub flowering
spectacularly in September.

CHASTE TREE
Vitex Agnus-Castus

8ft (2.4m)

Mauve

Aug-Oct

Full Sun

Free-draining soil

Hardy to -10C

Scented

Attracts pollinators

Avoid freezing winds

Bumble bees will exhaust themselves
visiting the Chaste tree. (September)

Growing Conditions The Chaste tree (Vitex agnus-castus) is native to the Mediterranean, so needs a warm, sunny location to thrive. Although hardy to -10C, its ability to withstand a particularly cold UK winter depends on it having ideal conditions, including good drainage and shelter from freezing winds. As such, it is best suited to the southern half of the UK, or milder costal areas, where happily it is also salt-tolerant. Further north and inland, it may need additional protection, such as being planted at the base of a warm, sheltered south-facing wall or given winter protection.

In general, if you have success with lavender, you should be able to grow Chaste tree.

Some nurseries list Chaste tree as half-hardy, suggesting that it is likely to be damaged by hard winters. However, in the wild it has been known to survive temperatures as low as -23C. In my Sussex garden it has thrived despite some recent winters where temperatures fell to -8C and plants like Agapanthus were killed. The wood of Chaste tree needs a long, hot summer to fully ripen, so winter hardiness might depend on the quality of the preceding summer. The good news is that even if top growth is damaged, Chaste tree can be cut back hard and will usually re-sprout readily.

One of the biggest enemies of Chaste tree is waterlogged soils. Wherever possible, provide it with excellent drainage. A friable loam-based soil with added sand or compost would be ideal. I grow mine in a low (6 inch) raised bed, which helps with winter drainage.

Growth Chaste tree is a moderately fast growing shrub which will readily form an open, roughly dome-shaped bush, or given time, a small tree. There are many cultivars, some being more compact and others more vigorous than the wild type tha

1 Pruning Vitex flowers on new wood, so can be cut back in winter without affecting its flowering. It appears to respond well to pruning, sending out new shoots even from older wood. Left to its own devices, it puts on new growth at a rate of 1–2ft (30–60cm) per year. New shoots from lower down, induced by pruning, can grow up to 4ft (1.2m) but are easily shortened or removed in the summer. I prune back or remove several shoots in summer to keep a nice rounded shape. I imagine heavy summer pruning might reduce autumn flowering, but I’ve never needed to prune so heavily that I can say for sure.

2 Foliage The leaves of the Chaste tree are deeply divided into fingers with 5–9 leaflets. They emerge coppery-yellow, turning to an attractive glaucous-grey-green as they mature.

3 Flowers The longer and hotter the summer, the earlier in the year Vitex blooms. In the UK it can be as early as mid-August, but more usually in September. Flowering spikes develop at the ends of new growth. The buds are covered in a fine white felt, creating a soft appearance. The flowers are arranged in long, upright spikes that typically measure 5 to 7 inches (12–18 cm) in length. These spikes are composed of many small individual flowers clustered together, giving them a dense, elongated, tiered shape.

Hummingbird hawk moth feeding
on my Vitex in August 2022

Planting Ideas

Vitex agnus-castus in a Mediterranean
style planting in my pond garden. (June)

Chaste Tree Vitex agnus-castus
Lavender Lavandula ‘Hidcote’
Sage Salvia ‘Caradonna’
African Lily Agapanthus ‘Poppin purple’
Red hot poker Kniphofia ‘Poco Citron’
Sage Salvia ‘Sensation rose’
Curry plant Helichrysum italicum
Triplet lily Triteleia ‘Rudy’
Thrift Armeria maritima
Creeping thyme Thymus serphyllum
Common box Buxus sempivirens
Stonecrop Sedum reflexum ‘Blue Spruce’
Red (& white) valerian Centranthus ruber

The same Vitex seen from a different
direction later in the year. (August)

Chaste Tree Vitex agnus-castus
Shrub rose Rosa ‘Desdemona’
Lavender Lavandula ‘Hidcote’
Dahlia Dahlia ‘Melody Harmony’
Sage Salvia ‘Sensation rose’
Garlic chives Allium tuberosum
Society garlic Tulbaghia violacea

Common Names

Vitex agnus-castus has several common names, each with an interesting origin:

Chaste Tree: This is the most common English name, derived from the ancient Greek belief that the plant reduced libido. Athenian women used the leaves in their beds to remain chaste during religious festivals.
Monk’s Pepper: This medieval name arose from the belief that monks used the plant’s dried berries to suppress sexual desire and maintain their vows of chastity.
Chasteberry: Refers to the small, pepper-like fruits of the plant, linking to its reputation for promoting chastity. (Note: Vitex rarely sets fruit in the UK)
Vitex: Tthe plant’s latin genus name means ‘to weave’ referring to the pliable stems that were once used for basket making.
Hemp Tree: Due to the similarity of its leaves to those of the hemp plant.
Abraham’s Balm: Origin unclear, but possibly related to its medicinal uses.
Lilac Chastetree: Refers to the color of its most common flower variety.
Texas Lilac: Used in some parts of the United States where it’s grown as an ornamental.
Cloister Pepper: Another name linking the plant to monastic use.
Sage Tree: Due to the sage-like scent of its leaves when crushed.

These names reflect the plant’s historical uses, appearance, and the beliefs associated with it across different cultures and time periods. The theme of chastity runs through many of these names, highlighting the plant’s long-standing reputation as an anaphrodisiac.

Cultivars

I have only grown the wild type of Chaste tree, with the lilac coloured flowers. However, in cultivation there are now dark purple, white and pink forms, as well as more vigorous and compact varieties. I’ve not grown any of these, but they do suggest a range of design opportunities:

‘Alba’: White flowered, up to 10 feet
‘Latifolia’: Large, spreading with finer leaves. To 15+ feet
‘Blue Diddley’: Compact variety with blue flowers. To 5 feet.
‘Pink Pinnacle’: Rather washed-out pale pink flowers. To 8 feet.
‘Montrose Purple’: Tall cultivar reaching up to 25 feet, with blue flowers.
‘Shoal Creek’: Features larger spikes of deep violet-blue flowers.
‘Abbeville Blue’: Another blue-flowered cultivar.
‘Blushing Spires’: Likely a pink-flowered variety.
‘Delta Blues’: A compact cultivar with blue flowers.
‘Blue Puffball’: A smaller cultivar that can be grown as a 3-to-6-foot shrub.
‘Cooke’s Blue’: A blue-flowered variety.
‘Cooke’s Pink’: A pink-flowered variety.
‘Rosea’: Another pink – perhaps slightly less wishy-washy than ‘Pink Pinnacle’.
‘Salinas Pink’: Apparently features ‘true pink flowers’.
‘Galactic pink’: Another attempt at an improved pink.

It is easy to picture how a pale-pink or white
variety would work in a garden like mine.

Chaste tree flower stems can be used as a short-lived cut flower.
I combined them with Desdemona roses in this vase.

Vitex (Chaste tree) makes a lovely cut flower, adding a unique structural element to floral arrangements. In autumn, I often have to prune back a few spikes that are hanging over a path or covering an adjacent plant. Using them in a flower arrangement means they don’t go to waste.

Here are some tips for using chaste tree as a cut flower:

Harvesting

Cut the flower spikes in the morning when they are about 1/3 to 1/2 open.
Choose stems with flowers that are just beginning to open for the longest vase life.
Use clean, sharp secateurs to make a clean cut at a 45-degree angle.
Remove any leaves that will be below the water line in the vase.

Conditioning

Immediately place cut stems in cool water.
Recut the stems underwater at a 45-degree angle to prevent air bubbles from blocking water uptake.
Allow the flowers to condition in cool water for several hours before arranging.

Arranging

Chaste tree flowers work well in both formal and informal arrangements.
The long spikes can add height and vertical interest to bouquets.
Combine with other late summer blooms such as like roses, zinnias, or dahlias.
The lavender-blue colour complements many other flower hues.

Vase Life

With proper care, chaste tree flowers can last 5–7 days in a vase.
Change the water every 2–3 days and recut stems to prolong their life.
Keep arrangements away from direct sunlight and heat sources.

Fragrance

The flowers have a pleasant, spicy scent that can add fragrance to arrangements.
The aroma is not overpowering, making it suitable for indoor use.

Using chaste tree as a cut flower allows you to bring its beautiful spikes and fragrance indoors, extending your enjoyment of this versatile plant beyond the garden.

Chaste Tree