Cassia javanica

Care Guide: Planting, Soil & Watering

Overview: The rainbow shower tree is a flowering deciduous tree that thrives in full sun and rich, well-drained soil topped with mulch. Though somewhat drought-tolerant, it flowers best with steady low-to-moderate watering.

Quick Care Requirements

Requirement	Ideal Condition
Planting Season	Spring to summer in zone 10b; spring to autumn in zone 11; year-round in zone 12+
Growth Rate	Moderate
Soil Type	Rich, well-drained soil with mulch
Water Need	Low to Moderate – drought-tolerant but prefers more water

Planting & Establishment

• Best Planting Season: Plant spring to summer in zone 10b, spring to autumn in zone 11, or year-round in zone 12+.
• How to Plant:
  • Hole Preparation: Dig a hole as deep as the root ball and 50-100% wider, loosening the base.
  • Soil Amendments: Mix organic matter, humus and dried leaves into some of the backfill, then mulch the surface to hold moisture – especially in summer.
  • Planting Depth: Loosen the root ball slightly and set the tree with its root collar level with the surrounding soil, not buried.
• Growth Speed & Expectations: A moderate grower reaching 6-12 m; its rate responds to watering, fertiliser and warmth, and it usually flowers and fruits within a few years.

Soil, Watering & Drainage Care

• Soil Mix & Drainage Needs: Wants rich, free-draining soil; in containers use a peat-and-perlite or potting mix with grit at the base for drainage, and keep it mulched.
• Watering Schedule & Technique:
  • Young / Newly Planted: Water every day for the first two weeks, ideally in the morning, then regularly through the first season.
  • Established: Water moderately once established; although drought-tolerant it blooms best with consistent moisture.
  • Seasonal Adjustments: Water more in summer heat and reduce in the cool season; mulch to conserve moisture.

Growing in Pots, Balconies & Indoors

The Java cassia is a big flowering tree – not a houseplant – but the grower says it can be kept in a container if held small as a dwarf or bonsai. A young tree makes a fine flowering patio pot for a few years before it outgrows one.

Quick Details

• Container Size: Minimum around 30 L (7 gal), better 100 L (20 gal) – start 50-100% bigger than the root ball and pot up
• Indoor Suitability: No – grow it outdoors
• Best Spot: Full sun
• Soil & Drainage: Peat with perlite (or potting mix) and lava grit in the base for drainage
• Watering in Pots: Small to average – drought tolerant but prefers more; water, then let it dry the same day

Indoors & On the Windowsill

• Not a houseplant: Too large and too sun-hungry for indoors – grow it outside.
• Overwintering: Tender to hard frost when young; in marginal climates a potted young tree can shelter in a bright, frost-free spot over winter.

On a Balcony or Patio

• Sun & size: A young tree gives a sunny balcony a burst of flower; give it full sun and shelter, but plan to plant it out or keep it dwarfed as it grows.
• Weight & wind: A big pot is heavy and a leafy young tree catches wind – stake it and site it securely.

Choosing the Pot, Soil & Long-Term Care

• Pot & potting-up: Keep it small as a dwarf or bonsai. Start in a pot 50-100% bigger than the root ball and pot up as it fills – minimum around 30 L (7 gal), better 100 L (20 gal).
• Drainage & mix: Use peat with perlite (or potting mix) and some lava grit in the base; sit it on a saucer and, when watering, let it fill but dry the same day.
• Feeding: Container trees need more feeding and added organic matter than trees in the ground.
• Refresh in dormancy: Once it is big, replace part of the soil and cut back the tree and roots in the dormant season to keep it in scale.

Bloom & Flower Guide

Quick Details

• Bloom Season: Spring to summer
• Time to First Bloom: A few years after planting, once the tree is established
• Flower Appearance: Fragrant pink flowers (deep pink to nearly white) in dense, weeping clusters, sometimes dozens per cluster
• Edibility: Ornamental – the flowers are not eaten

Detailed Blooming Overview

The rainbow shower tree is prized for its spring-to-summer show of fragrant pink blossoms hanging in weeping clusters. The scent and nectar draw bees and other pollinators.

Flower Characteristics

• Fragrant pink flowers, deepening from pale to rich pink.
• Carried in weeping clusters, often dozens of flowers together.

Bloom Care & Thinning

• Pollination: By bees and other insects.
• After bloom: Long seed pods follow the flowers – a normal part of the cycle.

Pests, Diseases & Troubleshooting

Overview: Java cassia / pink shower tree (Cassia javanica) is a warm-climate flowering legume tree, and like most such trees it is fairly robust: caterpillar defoliators, scale, mealybug and aphids (with their sooty mould) are the main pests, and leaf spot the main disease. Its bigger practical issues are abiotic — frost sensitivity when young, chlorosis on poor soils, and brittle wood.

Quick Troubleshooting Overview

Issue / Pest	Main Symptom	Primary Solution
Caterpillars / defoliators	Chewed, skeletonised compound leaves, frass	Tolerate/hand-pick, Bt on young larvae, encourage birds
Scale / mealybug	Encrustations, honeydew, sooty mould	Prune out, horticultural oil, beneficials
Aphids	Sticky, curled new shoots	Water jet, beneficials, insecticidal soap
Borers	Bore-holes and frass in stressed limbs	Keep trees vigorous, prune out infested wood
Leaf spot / mildew	Spots or powder on leaflets, leaf drop	Airflow, sanitation, copper or sulfur if needed
Chlorosis / weak wood	Yellow veined leaves; brittle limbs	Chelated iron, drainage; formative pruning

Common Pests & Management

• Caterpillars / Defoliators (Catopsilia, Eurema (sulphur butterflies) and other Lepidoptera):
  • Symptoms: Larvae of sulphur/emigrant butterflies and assorted moths chew and skeletonise the compound leaves, sometimes defoliating young trees; frass beneath.
  • Prevention & Control: Tolerate light feeding on established trees (they support butterflies), hand-pick or prune out heavy clusters on young trees, and encourage birds and parasitic wasps. Bt on young larvae for serious outbreaks.
• Scale Insects & Mealybugs (Coccus, Saissetia, Planococcus spp.):
  • Symptoms: Brown, grey or cottony encrustations on twigs, leaf axils and undersides; sticky honeydew and black sooty mould, with yellowing and dieback of heavily infested shoots.
  • Prevention & Control: Prune out encrusted wood, encourage lady beetles and parasitic wasps, and wash off honeydew; horticultural oil smothers crawlers — repeat to catch generations.
• Aphids (Aphis, Toxoptera spp.):
  • Symptoms: Colonies on soft new shoots and flower stalks with honeydew and sooty mould; curled, distorted young growth.
  • Prevention & Control: Encourage beneficials and hose off colonies; insecticidal soap for heavy outbreaks, and avoid excess nitrogen that fuels soft growth.
• Stem / Wood Borers (Cerambycid & buprestid beetles):
  • Symptoms: Larvae tunnel trunks and branches of stressed or damaged trees, leaving bore-holes, frass and weakened, wind-prone limbs.
  • Prevention & Control: Keep trees vigorous and unstressed, avoid bark wounds, prune out and destroy infested wood, and paint/seal large cuts; healthy trees resist attack.

Diseases & Fungal Issues

• Leaf Spot (Cercospora, Phyllosticta, Pseudocercospora spp.):
  • Symptoms: Brown or grey rounded spots, sometimes with yellow halos, on the leaflets in warm humid weather; heavy spotting yellows and drops foliage.
  • Treatment & Management: Improve airflow by thinning the canopy, rake up fallen leaves, and avoid overhead wetting; a copper fungicide only under sustained pressure.
• Powdery Mildew (Erysiphales):
  • Symptoms: White powdery coating on young leaves and shoots in crowded, humid conditions; distorted new growth.
  • Treatment & Management: Prune for light and airflow, remove affected shoots, and use sulfur or potassium bicarbonate if persistent.
• Root Rot & Sooty Mould (Phytophthora / Capnodium):
  • Symptoms: Wilting and dieback with dark rotted roots in waterlogged soil (root rot); black sooty film over honeydew from sap-suckers (sooty mould).
  • Treatment & Management: Plant in free-draining soil and avoid waterlogging for root rot; control scale, mealybug and aphids to clear the sooty mould, then wash it off.

Growing Difficulties & Abiotic Problems

• Frost Sensitivity (young trees):
  • Cause & Symptoms: Soft young growth and whole young trees are damaged or killed by frost; these are warm-climate legumes.
  • Correction Strategy: Plant in a warm, sheltered spot, protect young trees over their first cold seasons, and prune frost-damaged wood after the danger passes.
• Chlorosis in Alkaline / Poor Soil:
  • Cause & Symptoms: Yellowing between green veins on alkaline, compacted or waterlogged soils where iron and micronutrient uptake fails.
  • Correction Strategy: Improve drainage and add organic matter, adjust pH where practical, and apply chelated iron for a quick correction.
• Weak Wood & Limb Breakage:
  • Cause & Symptoms: Fast, soft growth makes for brittle branches that split in wind or under heavy bloom, especially with narrow forks.
  • Correction Strategy: Prune formatively for strong, wide-angled branches when young, thin the canopy to reduce wind-load, and remove damaged limbs promptly.
• Litter & Pod Drop:
  • Cause & Symptoms: Sheds flowers, leaves and long seed pods that litter beneath the canopy.
  • Correction Strategy: Site away from paving and pools where litter is a nuisance, and rake up pods; purely a maintenance matter.

What Helps — Products & Tools

A shade-tree kit: horticultural oil for scale and mealybug, insecticidal soap for aphids, Bt for caterpillar defoliators, chelated iron for chlorosis, and a copper or sulfur fungicide only if leaf spot or mildew is heavy. Sound formative pruning for strong branch structure prevents more damage than any spray.

Propagation Guide

Cassia javanica is easiest and most commonly raised from seed, which the site notes is not difficult; the hard legume coat germinates more evenly after soaking or scarifying. Cuttings are possible but slower and less reliable. Species seedlings are reasonably uniform, though some variation occurs.

Quick Propagation Specs

Best Propagation Method	Seed
Alternative Methods	Semi-hardwood cuttings (harder)
Propagation Difficulty	Easy (from seed)
Seed True-to-Type	Mostly uniform (some variation)
Best Propagation Season	Spring to summer (site)
Seed Germination Time	About 3–7 weeks (site)
Germination Temperature	26–30°C (79–86°F) (site)
Seed Sowing Depth	About 2–4 cm (1–1.8 in) (site)

Growing from Seed

Seed Handling & Viability

Collect seed from mature brown pods and store in a dry, dark place (site); fresh seed germinates most readily.

Dormancy & Pre-Sowing Treatment

Like most legumes the seed has a hard coat; a warm-water soak, or light scarification, before sowing improves and evens up germination.

Sowing Season

Spring to summer (site).

Sowing Depth & Spacing

About 2–4 cm (1–1.8 in) deep, preferably into individual pots; if sowing in place the site allows wide spacing of about 3 × 3 m (site).

Germination Conditions

Moist, well-drained soil in a warm, sunny position; the site reports best results at 26–30°C (79–86°F).

Germination Time

About 3–7 weeks (site); emergence may be staggered.

Seedling Care

Grow on in full sun with regular watering (site).

Stem Cuttings

The site roots cuttings from early spring, or at around 26°C (79°F), in a moist peat-based medium under high humidity with a rooting hormone and an enclosed/greenhouse setup; it notes cuttings are harder than seed.