Plant Profile & Key Characteristics
Overview: A twining evergreen climber reaching 1-3 m, grown for its showy clusters of bright red bowl-shaped flowers. It is evergreen in warm climates and used as an ornamental flowering screen or hedge.
Quick Specifications
| Specification | Attribute |
|---|---|
| Plant Type / Life Cycle | Perennial (evergreen to deciduous vine) |
| Foliage Type | Evergreen in warm climates; deciduous where cool |
| Mature Size | 1-3 m (3-10 ft) |
| Growth Rate | Fast to moderate |
| Hardiness | USDA zone 10b+ |
Growth Form & Structure
- Height & Spread: 1-3 m (3-10 ft) on a support; container-growable in a pot 100-200% larger than the root ball
- Growth Habit & Form: Twining evergreen vine that needs a trellis or support; grown as a flowering screen or hedge
- Lifespan & Maturity: Fast-establishing flowering plant reaching size within a couple of seasons
Anatomy & Physical Features
- Leaves & Foliage: Green to dark-green ovate leaves
- Flower Characteristics: Bright red bowl-shaped flowers in showy clusters
Primary Uses & Landscape Value
- Functional & Ornamental Roles: Ornamental flowering climber, screen and hedge; attracts pollinators
Care Guide: Planting, Soil & Watering
Overview: Clerodendrum splendens is a fast-to-moderate evergreen flowering vine for warm climates (hardy to about zone 10b) that grows in full sun to half shade. It needs rich, well-draining soil kept consistently moist, plus a trellis or support to climb.
Quick Care Requirements
| Requirement | Ideal Condition |
|---|---|
| Planting Season | Spring–summer in zone 10b, spring–autumn in 11, year-round in 12+ |
| Growth Rate | Moderate to Fast |
| Soil Type | Rich, moisture-retentive yet well-draining |
| Water Need | Moderate to High – keep the soil moist, never bone-dry |
Planting & Establishment
- Best Planting Season: Plant in spring to summer in zone 10b, spring to autumn in 11, and year-round in zone 12+.
- How to Plant:
- Hole Preparation: Dig a hole larger than the root ball.
- Soil Amendments: Mix in organic matter, chopped dead leaves and humus.
- Planting Depth: Set the plant in and cover it lightly, keeping the root collar at soil level.
- Growth Speed & Expectations: Fast to moderate, climbing 1–3 m (3–10 ft); train it onto a trellis or support.
Soil, Watering & Drainage Care
- Soil Mix & Drainage Needs: Use soil that holds moisture without staying waterlogged, and mulch to keep roots cool and moist; in pots use potting mix or peat with perlite and refresh it every few years as drainage declines.
- Watering Schedule & Technique:
- Young / Newly Planted: Keep the soil moist for the first few weeks until the plant establishes.
- Established: Water regularly so the soil never fully dries; these plants like an average-to-generous supply.
- Seasonal Adjustments: Increase in summer heat; reduce in cooler months.
Note: Best grown in a container, since named cultivars are propagated by grafting or cuttings rather than seed.
Climate, Light & Hardiness
Clerodendrum splendens is a warm-climate flowering vine that grows in full sun to half shade across tropical, subtropical, and mediterranean conditions. It is reliably hardy outdoors only from about USDA zone 10b upward.
Quick Climate Specifications
| Climate Zones | Tropic, subtropical, or Mediterranean |
|---|---|
| USDA Hardiness Zones | Approximately 10b and warmer |
| Frost Tolerance | Low |
| Light Conditions | Full sun to half shade |
Sunlight & Light Exposure
Optimal Light Setup
Grows well from full sun through half shade, with best flowering in good light.
Direct Sun Requirement
Tolerates full direct sun in warm climates.
Temperature Extremes & Hardiness
USDA Hardiness & Regional Limits
Suited to USDA zone 10b and warmer; where winters bring frost, it needs to be grown in a sheltered container or treated as a warm-season plant.
Cold Damage & Winter Protection
Cold slows and can damage growth; the plant establishes and grows best at warm temperatures around 21–25°C (70–77°F).
Frost Sensitivity
Frost-sensitive.
Growing in Pots, Balconies & Indoors
Clerodendrum splendens (flaming glory bower) is a showy scrambling shrub and climber (1-3 m). The grower does not rate it as a houseplant – it needs strong light for its brilliant flowers – but it thrives in a large pot with support on a sunny balcony or patio.
Quick Details
- Container Size: A pot 100-200% larger than the root ball (or a smaller pot with roots trimmed at planting), with a trellis for the climbing stems
- Indoor Suitability: Not a houseplant – too little indoor light for its flowers
- Best Spot: Full sun to half shade
- Soil & Drainage: Potting mix or peat/coir with perlite; refresh as drainage declines
- Watering in Pots: Average to generous, with free drainage
Indoors & On the Windowsill
- Not a houseplant: The grower marks it unsuitable indoors; the vivid red-and-white flowers need strong light a room cannot give.
- Bright sun-room: A very sunny conservatory with a support to climb is the only real indoor option.
On a Balcony or Patio
- Sun & support: Give a warm, sunny, sheltered spot and a trellis or wires for the scrambling stems; potted climbers dry fast against warm walls, so keep them watered.
Choosing the Pot, Soil & Long-Term Care
- Pot & drainage: A container 100-200% larger than the root ball with strong drainage holes and no standing saucer, plus a trellis; or plant in a smaller pot and trim the roots when you do.
- Potting mix: Potting mix or peat/coir with perlite; replace the soil after a few years as drainage declines.
- Feeding: Add organic matter and fertiliser at least once a year (the grower’s advice).
- Refresh the mix and pot on about every two years, lightly root-pruning and top-pruning to keep it vigorous.
Fertilizing & Feeding
A vigorous flowering vine that rewards regular feeding through its active growing season with strong stem extension and better bloom; growth slows and feeding needs drop off where winters are cool.
Quick Fertilizing Specs
| Feeding Level | moderate |
|---|---|
| Main Nutrient Priority | Balanced feeding with a nitrogen lean early to build the climbing framework, shifting to a more balanced blend as flowering approaches |
| Best Feeding Period | Warm active-growth months, from new spring growth through summer bloom |
| Organic Options | Compost or well-rotted organic matter worked in at planting and refreshed as a mulch layer supports steady growth |
| Soil pH | Adaptable to a range of garden soils but performs best in rich, well-drained soil that does not stay soggy |
| Reduce/Stop Feeding | Taper off as growth slows going into the cooler season and hold feeding while the plant is quiet |
Feeding by Growth Stage
Newly Planted / Establishment
Support root establishment without pushing soft, weak growth before the root system is ready to support it
| Nutrient direction | Light, balanced feeding that favors root development over top growth |
|---|---|
| Timing | First growing season after planting, once new growth confirms the plant has taken hold |
| Frequency | A couple of light feedings spaced through the establishment period is usually enough |
| Fertilizer types | A balanced, complete fertilizer at a gentle rate, Compost or organic matter worked into the planting hole |
| Precautions | Avoid heavy or concentrated feeding right after planting, which can stress developing roots |
Active Growth and Bloom
Fuel vigorous vine extension and support the clustered red blooms through the warm season
| Nutrient direction | A nitrogen-forward complete fertilizer while the vine is putting on new growth, moving toward a more balanced blend as flower clusters form |
|---|---|
| Timing | Warm months of active growth, continuing through the bloom period |
| Frequency | Several light feedings spread across the active growing season keep growth steady without forcing it |
| Fertilizer types | Balanced or nitrogen-forward complete fertilizer, Periodic top-dressing with compost or aged organic matter |
| Routine trace nutrients | iron, manganese |
| Precautions | Overfeeding with high-nitrogen products can push lush foliage at the expense of flowering; ease off if bloom is sparse despite strong leaf growth |
Cool-Season Rest
Let the vine settle into its natural slowdown where cooler temperatures cause partial leaf drop or dormancy
| Nutrient direction | None – withhold fertilizer while growth is inactive |
|---|---|
| Timing | Cooler months in climates where the plant loses leaves or growth pauses; largely skipped where it stays evergreen and active year-round |
| Frequency | No feeding at this stage |
| Fertilizer types | No feeding at this stage – resume with the return of active spring growth |
| Precautions | Do not fertilize a dormant or slow-growing plant; wait for clear signs of new growth before feeding again |
Nutrient Deficiency Signs & Corrections
Overall pale or yellowish-green foliage, more pronounced on older, lower leaves, with reduced vine vigor
| Possible causes | Nitrogen deficiency from light or infrequent feeding, Waterlogged or compacted soil limiting root uptake, Root stress from a container that has become too small |
|---|---|
| Appears first on | Older, lower leaves first, spreading upward if uncorrected |
| What to check | Recent feeding history and fertilizer type used, Soil drainage and whether roots sit in standing water, Root crowding if grown in a container |
| Possible correction | Resume regular balanced feeding during active growth and correct any drainage or root-crowding issue that is limiting uptake |
New growth turns yellow between green veins while the veins themselves stay green
| Possible causes | Iron unavailability in alkaline or overly wet soil, High soil pH locking out micronutrients, Root damage limiting nutrient uptake |
|---|---|
| Appears first on | Newest leaves at the growing tips |
| What to check | Soil pH and drainage around the root zone, Whether the pattern is interveinal on new growth specifically, Recent overwatering or root disturbance |
| Possible correction | Correct pH toward a more favorable range for nutrient uptake and apply a chelated iron product per its label if the pattern persists |
Leaf margins show scorch-like browning and flowering is weaker or shorter-lived than expected
| Possible causes | Potassium deficiency from an unbalanced or nitrogen-only feeding routine, Drought stress reducing nutrient movement, Salt buildup interfering with uptake in container culture |
|---|---|
| Appears first on | Margins of older leaves first |
| What to check | Balance of the fertilizer being used, Watering consistency during bloom, Salt crust on soil surface in containers |
| Possible correction | Switch to a balanced fertilizer that supplies adequate potassium and keep watering consistent through the bloom period |
Pruning, Training & Seasonal Maintenance
Clerodendrum splendens is a twining herbaceous vine, not a free-standing shrub, so its pruning centers on managing growth along a trellis, fence, or other support rather than shaping an independent framework. Like its shrubby relatives it flowers in clusters at the tips of current growth, so the safest time to prune is right after a bloom cycle finishes, allowing fresh growth time to develop and carry the next flush of flowers. It tolerates moderate to fairly hard cutting back, which is useful since left untrained it will twine into a tangled mass rather than the tidy flowering screen it is usually grown for.
Quick Pruning & Maintenance Specs
| Pruning Tolerance | Moderate to High |
| Primary Pruning Window | Immediately after flowering finishes (timing shifts with climate) |
| Typical Frequency | Once a year for renewal, plus ongoing tying-in through the growing season |
| Main Objective | Train twining stems onto their support and renew flowering laterals |
| Young Plant Priority | Select and tie in 1–3 main twining leaders onto the support structure |
| Mature Plant Priority | Cut back flowered laterals to renew bloom; remove tangled, unsupported growth |
| Best Tool Type | Bypass secateurs, plus soft ties to manage the twining stems |
| Avoid Heavy Pruning During | While the plant is actively in bloom |
Pruning by Plant Age & Size
Newly Established
Remove only damaged growth in the first season and begin tying the young twining stems to their support as they extend, rather than letting them wander and self-attach randomly.
Young / Formative
This is cane/vine-selection training, not a shrub framework: choose one to three vigorous leaders to become the main twining stems, tie them to the trellis or fence at intervals, and remove weaker competing shoots so the plant’s energy goes into the selected leaders.
Mature / Established
On an established vine, the main job each year is cutting back the lateral shoots that flowered to a couple of buds, which renews the flowering wood for the next cycle, and removing any growth that has come loose from the support and is tangling into a mass.
Flowering & Fruiting Wood
Flowers form in clusters on the current season’s lateral growth, not on old persistent wood, so cutting back flowered laterals after bloom does not cost the next display — it is what stimulates the new laterals that will flower next. Pruning before flowering finishes is what actually removes an upcoming bloom.
Structural Pruning & Training
Because this is a twining vine rather than a self-supporting shrub, structure is built by tying main leaders to a support and periodically cutting back the shorter flowering laterals that grow off them — closer to how a flowering climber is trained than how a shrub is shaped. Remove any stems that have escaped the support and begun twining around neighboring growth, which quickly becomes a tangled mass if left unchecked given this species’ fast to medium growth rate.
Special Growth to Remove
- Dead wood and weak branches: remove at any time, the same as noted in this species’ own care guidance.
- Flowered lateral shoots: cut back after bloom to encourage renewed flowering growth.
- Unsupported, tangling stems: redirect onto the support or remove if they cannot be tied in cleanly.
Tools
- Bypass secateurs: for cutting back flowered laterals and thinning tangled growth.
- Loppers: for older, thickened base growth on a mature vine.
- Soft ties or stakes: essential for guiding twining leaders onto the trellis or fence this species needs as support.
Tool Hygiene & Disease Risk
Routine hygiene is generally adequate. This species attracts aphids, spider mites and mealybugs, which can build up on soft new growth after cutting back laterals, so check regrowth for pests rather than assuming dieback is pruning-related.
Cut Placement & Technique
Cut flowered laterals back to one or two buds from the main twining leader, use thinning cuts to remove entire unwanted stems back to their point of origin rather than leaving stubs, and tie remaining growth to the support with soft ties that will not girdle the stem as it thickens.
Heavy Pruning & Rejuvenation
Tolerates a fairly hard annual cutback of its lateral growth well; if the vine has become a tangled mass beyond what selective cuts can fix, it can be cut back hard to its main leaders after flowering and will retwine and rebuild its lateral growth within the same growing season.
Post-Pruning Care
Water normally after cutting back, retie any loosened leaders to their support promptly so new growth trains in the right direction from the start, and watch the resulting flush of new growth for aphids, spider mites and mealybugs.
Common Pruning Mistakes
- Letting twining growth wander off its support instead of tying it in as it extends, resulting in a tangled mass.
- Treating this species like a self-supporting shrub instead of training it as a vine.
- Pruning before flowering finishes, removing buds that were about to open.
When NOT to Prune
Avoid pruning while the plant is in active bloom, and avoid a hard cutback right after transplanting or after first installing it on a new support, before it has begun climbing well.
Recommended Tools (by task)
- bypass_secateurs: the main tool for cutting back flowered laterals and thinning tangled stems.
- loppers: for thicker old growth at the base of a mature vine.
- soft_ties_stakes: to train twining leaders onto the trellis or support this species requires, rather than letting it self-attach randomly.
Propagation Guide
Clerodendrum splendens can be propagated vegetatively from stem cuttings. Seed is also possible where viable seed is produced and is appropriate for the species or genus-level plant.
Quick Propagation Specs
| Best Vegetative Method | Stem cuttings |
| Seed | Possible where viable seed is produced |
| Grafting | Not required |
Cuttings root best in early spring at around 21-25°C (70-77°F), in moist, humid conditions using a peat-based mix and a rooting hormone; a greenhouse or a small perforated plastic box helps hold humidity, and the first roots typically take a few weeks to form. For seed, a peat mix with vermiculite (or another well-ventilated medium) in a sunny, humid spot at the same 21-25°C range works well.
Stem Cuttings
Take healthy non-flowering stem material with viable nodes. Remove lower leaves, place the cutting in a clean, free-draining propagation medium, and maintain humidity without keeping the medium waterlogged until roots develop.
Growing from Seed
Use mature, viable seed when seed propagation is desired, sown very shallowly (about 0.5-1cm/0.2-0.4in) since germination is light-dependent. Seed-grown plants may vary, especially on cultivated or genus-level pages.
Aftercare
Keep rooted cuttings protected from severe stress while they establish, then increase light and normal watering gradually.
Note: Germination is reported in the 2-6 week range for this genus, often around 2-4 weeks under warm conditions (above 25C/77F).
Bloom & Flower Guide
Quick Details
- Bloom Season: Autumn to winter in the tropics; spring in cooler areas
- Flower Appearance: Bright red bowl-shaped flowers in generous clusters
- Edibility: Not eaten – an ornamental flowering climber
Detailed Blooming Overview
Clerodendrum splendens (flaming glorybower) is an evergreen to deciduous climber grown for its blaze of scarlet bloom. Flowering comes in autumn and winter in tropical climates, or in spring where conditions are cooler, in tropical, subtropical and Mediterranean gardens, roughly zone 10b and warmer. It can be trained up supports or used as a flowering hedge.
Flower Characteristics
- Vivid red, bowl-shaped flowers.
- Massed into large, eye-catching clusters.
- Long-lasting and a strong focal point against glossy foliage.
Bloom Care & Thinning
- Training & pruning: Guide the stems onto a support and prune after flowering to keep it shapely; it blooms on new growth.
- Position: Warmth, shelter and steady moisture bring on the richest display.
- Pollination: The red flowers draw butterflies and sunbirds.
Pests, Diseases & Troubleshooting
Overview: Clerodendrum splendens and its relatives are classic tender ornamentals that are magnets for whitefly and other greenhouse sap-suckers, which bring sticky honeydew and sooty mold. Keep plants vigorous in bright, humid, airy conditions, inspect leaf undersides often, and treat sap-suckers early with soaps and oils.
Quick Troubleshooting Overview
| Issue / Pest | Main Symptom | Primary Solution |
|---|---|---|
| Whitefly | Clouds of white flies under leaves; sticky honeydew and sooty mold | Yellow sticky traps, insecticidal soap, oil |
| Mealybugs | White cottony masses in leaf axils and stems | Dab with alcohol, insecticidal soap, oil |
| Spider mites | Fine stippling and webbing in warm, dry air | Raise humidity, hose foliage, horticultural oil |
| Aphids | Clustered on soft shoot tips; distorted growth | Water jet, insecticidal soap |
| Scale | Brown or waxy bumps on stems; honeydew | Scrape off, horticultural oil |
| Leaf spot | Brown/black spots and yellowing leaves | Improve airflow, avoid wetting foliage |
Common Pests & Management
- Whitefly (Trialeurodes vaporariorum / Bemisia tabaci):
- Symptoms: Signature pest: tiny white flies rising in clouds when disturbed, with nymphs and honeydew on leaf undersides leading to sooty mold and weakened, yellowing growth.
- Prevention & Control: Yellow sticky traps to monitor; insecticidal soap or horticultural/neem oil to undersides in the evening, repeated to catch hatches; encourage Encarsia parasitic wasps under glass.
- Mealybugs (Planococcus citri / Pseudococcus spp.):
- Symptoms: White cottony tufts wedged in leaf axils, stem joints and undersides, with honeydew and stunted, distorted growth.
- Prevention & Control: Spot-treat with a cotton bud dipped in alcohol; insecticidal soap or oil for wider infestations; isolate new plants and check regularly.
- Two-spotted spider mite (Tetranychus urticae):
- Symptoms: Fine pale stippling, a bronzed dull cast to leaves, and fine webbing beneath in warm, dry indoor air.
- Prevention & Control: Raise humidity and hose or wipe foliage; horticultural or neem oil and insecticidal soap; predatory mites in enclosed spaces.
- Aphids (Aphis spp.):
- Symptoms: Clusters of soft insects on tender shoot tips and buds, causing curling, honeydew and ants.
- Prevention & Control: Dislodge with water, insecticidal soap or oil on heavy colonies; conserve natural predators.
- Soft/brown scale (Coccus hesperidum):
- Symptoms: Flat brown or waxy bumps along stems and leaf veins, with sticky honeydew and sooty mold.
- Prevention & Control: Scrape off light infestations; horticultural oil to smother, repeated; prune out badly encrusted stems.
Diseases & Fungal Issues
- Leaf spot (Cercospora / Phyllosticta):
- Symptoms: Brown to black spots that enlarge and merge, with yellowing and leaf drop in humid, still conditions.
- Treatment & Management: Improve airflow and spacing, avoid overhead watering, remove affected leaves; copper fungicide only if persistent.
- Sooty mold (secondary fungi on honeydew):
- Symptoms: Black sooty film coating leaves and stems wherever sap-suckers have left honeydew, blocking light.
- Treatment & Management: Control the underlying whitefly/scale/mealybug; wipe or wash off the mold once the pests are gone.
- Root rot (Pythium / Phytophthora):
- Symptoms: Wilting, yellowing and collapse from soggy soil; roots dark and mushy.
- Treatment & Management: Use free-draining mix, water only when the surface dries, and never leave pots standing in water.
Growing Difficulties & Abiotic Problems
- Chlorosis / leaf yellowing:
- Cause & Symptoms: Yellowing between veins from high pH, cold, or overwatering locking up iron and magnesium.
- Correction Strategy: Correct watering, feed with a balanced feed plus chelated iron/magnesium, and keep tender types warm.
- Leaf drop & poor bloom:
- Cause & Symptoms: Insufficient light, cold drafts or sudden change causes leaf drop and few flowers on tender species.
- Correction Strategy: Give bright light, steady warmth (avoid drafts) and even moisture; feed in the growing season.
- Sunburn:
- Cause & Symptoms: Scorched, bleached patches when a shade-acclimated plant is moved abruptly into strong sun.
- Correction Strategy: Acclimate gradually and provide light shade in the hottest part of the day.
What Helps – Products & Tools
Lead with cultural control – bright airy conditions, clean foliage, yellow sticky traps and isolating new plants. When needed, insecticidal soap and horticultural/neem oil manage whitefly, mealybug, scale, mites and aphids, and a copper fungicide addresses stubborn leaf spot.
