Diamonds in the Dark Purely Purple Crepe Myrtle

Diamonds in the Dark 'Purely Purple' (Lagerstroemia indica x fauriei) carries deep purple flowers against foliage so dark it reads black from across a garden. That pairing is unusual: most purple flowering shrubs sit on green leaves and lose half their impact. It grows to about 3m tall and 2m wide, small enough for a courtyard, and it is fast, deciduous and colours up before leaf drop.

Why you'll love it

• The deepest flower colour in the series. True purple panicles right through summer, held above near black foliage instead of green.
• Foliage that works when nothing is flowering. The dark leaves are why this plant still looks deliberate in October and again in March.
• Compact by design. Bred down to about 3m tall, against the 6m to 8m of older crepe myrtles, so it belongs in a small garden.
• Fast growing and hardy. It makes useful size quickly, and it is frost hardy, heat tolerant and drought tolerant once the roots are down.

Where it works best

Feature planting. The dark foliage sits best against something pale: a rendered wall, light paving, or silver and grey foliage nearby.

Small gardens. Allow roughly 1.5m from a fence or wall for the 2m canopy. It suits a courtyard or a front bed where a shade tree would be too much.

Driveways, avenues and pots. Space plants 2.5m to 3m apart for a repeated run, a touch more than the mature width. A 500mm pot or larger holds one for years in full sun.

Growing Purely Purple crepe myrtle in Australia

Position and climate. Full sun. Six hours is the minimum and more is better for both flower count and leaf colour. It suits cool temperate, warm temperate, subtropical and Mediterranean gardens, though in cooler southern districts the flowering window is shorter and starts later.

Soil. Drainage matters more than fertility here. On clay, mound the planting position and improve the bed with compost first, then mulch 75mm deep clear of the trunk.

Water and feed. Twice weekly deep watering through the first summer, then a fortnightly soak in dry weather. One application of complete slow release fertiliser in early spring covers the whole year.

Pruning. Prune in late winter when the branches are bare. Thin the crossing wood and tip the spent flower heads, but resist cutting the framework back hard, which ruins the shape and delays flowering.

What to expect when it arrives

It comes in 200mm pots sold in packs of six, and as single 300mm plants. The pack is the sensible buy for a run of several, while the 300mm plant gives more presence immediately if you only want one.

Sent between late autumn and early spring it arrives bare stemmed, because it is deciduous. Buds break when the soil warms, usually within weeks of a spring planting. Delivered Australia wide, delivery from $29.95, minimum order of $300 before delivery, with advanced and large stock freighted at cost and our 30 day healthy plant guarantee.

Plant care guides and related reading

• Growing Diamonds in the Dark crepe myrtles
• The full crepe myrtle care guide
• See the whole crepe myrtle range
• Planting a run: browse trees suited to driveways and avenues

Common questions

Will the leaves stay black all year?

They stay dark from bud break through to autumn, deepest in full sun and duller in shade. Then they colour and drop, and the plant stands bare through winter.

How fast does it grow?

Quickly for a flowering shrub. With sun and water it approaches its 3m height within three to four seasons, then thickens rather than climbing further.

Can I plant it near a paved courtyard?

Yes, as long as you leave room for the 2m canopy. About 1.5m to 2m back from paving keeps the branches from forever brushing the path.

Do I have to prune it every year?

Not strictly, but a light late winter prune keeps the shape open and encourages the new wood the flowers form on. Skipping it costs you flowers within a couple of seasons.