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Glory tree

Habit (mature) - Forest & Kim Starr / Wikimedia Commons - CC BY 3.0

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Glory tree

Tibouchina granulosa

A spectacular flowering tree from the Atlantic Forest of eastern Brazil, where it is known as quaresmeira, grown for repeated flushes of intense royal-purple flowers borne in showy panicles over glossy, ribbed, dark-green leaves. The bloom can recur several times a year, smothering the canopy in violet and dropping a carpet of purple petals beneath. Honesty first: this is a frost-tender tropical tree (Melastomataceae), native to the Atlantic Forest of eastern Brazil (POWO, Kew; Flora e Funga do Brasil), hardy only in roughly USDA zone 10 and warmer, for tropical and frost-free subtropical gardens. It grows fast but the wood is brittle and breakable in wind, so it is a short-to-medium-lived showpiece rather than a long-term structural tree. A taxonomic note worth carrying: the accepted name is now Pleroma granulosum (POWO, Kew; GBIF), with Tibouchina granulosa kept as a widely-used synonym — the name most gardeners and nurseries still use. Its flowers are buzz-pollinated, releasing pollen only to native bees that vibrate the anthers.

Climate fit: narrow (17/100)

Focal point

Structure

Light

Full sun

Water

Moderate water

Mature size

180-480" tall · 240" apart

Hardy in zones

10a-11b

mild to nearly frost-free winters

Native in Illinois

This is a strictly ornamental flowering tree, grown for its spectacular purple bloom — no part of it is eaten, so treat it as inedible.

°C

°F

Cold hardiness

Future

2050

2100

These values are location-based: this location's current hardiness is the baseline, and the 2050 value is a projected future climate for this same location.

Now

Zone 6b

USDA

Published baseline for this location from 1991-2020.

Source: USDA Plant Hardiness Zone Map 2023 (1991-2020 climatology) via ArcGIS FeatureServer

Won't grow here

2050

Zone 7a

Plotwright

Projected zone for this same location in 2050 (2041-2070) using SSP3-7.0 (regional rivalry).

Won't grow here

In plain terms: This location is in Zone 6b today. Its hardiness profile is cold winters, and coldest nights are typically around -3°F. By 2050, the projected hardiness zone is Zone 7a based on SSP3-7.0 (regional rivalry). That is a +0.5-zone shift from Zone 6b to Zone 7a by 2050.

Out of range today and still out of range in 2050.

Heat tolerance

Future

2050

2100

Heat tolerance values are location-based too: heat days today are observed at this site, and the 2050 value projects this same location under a future climate.

Loading AHS heat-zone data for this location...

Where this plant fits

Suitable across 17 ecoregions — 11 climate-resilient through 2070 · 6 newly possible by 2070. Best matches first.

Atlantic coastal pine barrens

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California coastal sage and chaparral

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Central Pacific Northwest coastal forests

Eastern Australian temperate forests

New Zealand North Island temperate forests

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Northern Pacific Alaskan coastal forests

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What it needs

Conditions

Light

Full sun

Water

Moderate water

Spacing

240"

Habit

Evergreen tropical flowering tree (Melastomataceae), fast-growing but brittle-wooded, with a rounded crown of glossy ribbed leaves; frost-tender (USDA zone 10+); accepted name Pleroma granulosum

Care tips

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Recognize the honest verdict: this is a frost-tender Brazilian Atlantic-Forest tree for USDA zones 10a-11b only — if you get frost, it is a knowledge entry, not a planting option, so choose a hardy flowering tree instead.

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Give it full sun, warmth, and moist but well-drained slightly acidic soil, and keep moisture steady to fuel the repeated purple flushes that make it worth growing.

•

Plant it in a sheltered spot out of strong wind and build a sound branch structure with early staking and pruning — the wood is fast-grown and brittle, so wind and storm breakage are the main long-term risk.

Lifecycle

Planting

Plant only in frost-free tropical and warm-subtropical gardens (USDA zones 10a-11b) in full sun, in moist but well-drained, moderately fertile, ideally slightly acidic soil. Give it a sheltered spot out of strong wind because the wood is brittle, and site it where its repeated purple bloom can be seen as a focal point. Anywhere that frosts, it is not a candidate for outdoor planting.

Transplanting

Move it as a young container plant at the start of the warm, wet season so it can establish before any dry or cool stress; keep the rootball intact and water generously through establishment. Set it in its permanent sheltered position early, as the fast, brittle growth does not take well to later disturbance.

Early growth

Young trees grow quickly in warmth and full sun, often flowering within a few years. Keep moisture steady, feed lightly for strong growth, and stake and shape early — the soft, brittle wood is prone to breakage, so a sound branch structure built young pays off. Protect from any frost, which kills tender growth.

Maturity

A mature tree reaches roughly 15-40 feet with a rounded crown and delivers its signature repeated flushes of royal-purple flowers. Fast growth is paid for in brittle wood and a relatively short-to-medium lifespan, so expect wind and storm breakage over time and treat it as a glorious but not permanent specimen.

Propagation

Propagated readily from semi-hardwood cuttings, which root well in warm, humid conditions and reproduce the parent reliably; it can also be grown from seed. Either way it needs frost-free warmth to establish.