Madagascar Caudex Plants: Complete Growing Guide (2026)

A complete Madagascar caudex plant guide: light, watering, soil, dormancy, seed germination, and how to build a thick caudex on Pachypodium, Adenium, and Adenia.

Patrick Ivern · 2026-02-08 · 21 min read

Key Takeaways

• Madagascar’s 80-million-year isolation produced the planet’s richest caudex flora: 20+ Pachypodium species, many Adenia, and other water-storing succulents built to ride out 5–10 month dry seasons.
• Light is the make-or-break factor. These plants want 6–8 hours of direct sun; indoor windows deliver a fraction of outdoor intensity, so a strong grow light or a summer outdoors is usually essential for real caudex development.
• Beat rot with drainage and restraint. Use a 70–80% mineral mix, water only when the pot is bone dry (the skewer test), and give zero water during leafless winter dormancy.
• Honor dormancy. Yellowing, dropping leaves in autumn are normal; reduce water as they fall, stop entirely when bare, keep cool (50–65°F), and wake the plant slowly in spring.
• Fat caudices come from patience, not pampering. Under-pot, feed lightly with low-nitrogen fertilizer, give maximum light, and expect 5–10+ years. Buy only nursery-propagated stock, since the whole genus is CITES-protected.

Madagascar hosts the world’s most spectacular collection of caudex plants: bizarre, sculptural succulents with swollen, water-storing trunks that look like living sculpture.

More than 20 Pachypodium species, 18 Adenia varieties, and a host of other caudiciforms evolved here over 80 million years of isolation. They bank months of water in flask-shaped bases, push out crowns of leaves seasonally, and ask for very little once you understand their biology.

What makes Madagascar caudex plants unique?

These plants developed extreme water-storage adaptations to survive the island’s brutal dry seasons, which last 5 to 10 months a year.

The caudex (from the Latin for “tree trunk”) works as a living water tank built from specialized parenchyma cells that hold moisture like tiny reservoirs. When drought hits, the plant simply shuts down: it drops every leaf, goes dormant, and lives off stored resources until the rain returns.

The island’s isolation made it an evolutionary hotspot. When Madagascar split from Africa around 160 million years ago, plant lineages evolved independently into forms found nowhere else. Pachypodium is the poster child: only one species exists in Africa, while over 20 thrive across Madagascar’s varied microclimates.

Each species adapted to specific conditions, whether limestone outcrops, quartzite formations, coastal dunes, or interior plateaus.

Which Madagascar caudex species should beginners start with?

Start with Pachypodium lamerei, commonly called the Madagascar Palm even though it isn’t a palm. It tolerates the widest range of conditions, grows relatively fast (4–8 inches of height a year), and forgives the odd watering mistake better than the finicky specialists. It’s also widely available, usually $20–50 for a 6–12 inch plant versus $100+ for rarities.

P. geayi is another good first plant, with similar toughness and a dramatic look of silvery-gray spines and narrow leaves. Both adapt to indoor life at a bright south window or under grow lights, unlike the habitat specialists that demand outdoor conditions.

Advanced collectors chase species like P. brevicaule, which grows barely 6 inches tall but builds a massive 10-inch flattened caudex that mimics the rocks it hides among. It grows excruciatingly slowly, maybe 1 cm of diameter a year, and demands perfect drainage, intense light, and absolute respect for dormancy.

A quick shortlist by experience level:

• Easiest: Pachypodium lamerei (most adaptable), Pachypodium geayi (striking silver), Adenium obesum (desert rose, flowers readily), Operculicarya decaryi (bonsai-friendly).
• Intermediate: Pachypodium densiflorum (massive caudex), Pachypodium rosulatum (variable forms), Adenia olaboensis (interesting vine).
• Advanced: Pachypodium brevicaule (rock-mimicking dwarf), Pachypodium eburneum (critically endangered), Adenia montagnacii (specialized vine).

How much light do Madagascar caudex plants need?

They need at least 6–8 hours of direct sun daily, and most species are happy in full sun all day.

These plants evolved under intense tropical sun at 12–25° south, getting roughly 12 hours of daylight year-round with little cloud cover in the dry season. Too little light causes etiolation: weak, stretched growth with thin stems and a poor caudex.

The intensity gap surprises most new growers. A bright room with big windows gives maybe 500–1,000 foot-candles, while full outdoor sun delivers around 10,000. That 10–20x difference is exactly why indoor plants go leggy and never bulk up.

Indoors, supplement window light with full-spectrum grow lights running 12–14 hours a day, positioned 6–12 inches above the tips to deliver 2,000–4,000 foot-candles. Many growers move plants outside for summer (May–September), which dramatically improves the caudex and triggers flowering.

A compact full-spectrum LED like the SANSI 36W is an easy way to close that intensity gap on a windowsill without scorching the foliage.

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Can Madagascar caudex plants tolerate shade?

No. They may survive in bright indirect light for months without dying, but growth stalls, the caudex stops developing, and the plant slowly declines.

The biology is straightforward: photosynthesis needs light energy to turn CO2 and water into sugars, so insufficient light means insufficient sugar, and the plant has nothing to store in the caudex or spend on growth.

P. lamerei handles lower light better than most, getting by on 4–5 hours of direct sun, while P. brevicaule and the other dwarfs demand maximum intensity or they grow abnormally. A simple diagnostic: if your plant is getting taller but the caudex isn’t thickening proportionally, light is the problem. Proper light produces compact, stocky growth with dramatic caudex expansion.

How often should I water my Madagascar caudex plant?

Water thoroughly only when the soil is completely dry. In practice that’s every 7–14 days during peak summer growth and every 14–21 days in spring and fall.

In winter dormancy, drop to once every 4–6 weeks, or stop entirely for leafless dormant plants. The caudex makes these plants exceptionally drought-tolerant, since they evolved to survive 5–10 months without rain.

The key is reading soil moisture properly: water when the mix is bone dry all the way through, not just at the surface. Use the skewer test: push a wooden skewer to the bottom of the pot, leave it a minute, and pull it out. If any moisture or soil clings to it, don’t water; if it comes out clean and dry, water thoroughly.

Thorough means saturating the whole soil volume until water runs freely from the drainage holes. That wets every root zone and flushes accumulated fertilizer salts. Never give little sips that only dampen the top inch, which encourages shallow roots and raises rot risk.

What happens if I overwater?

Overwatering causes root and caudex rot, the leading killer of cultivated Madagascar caudex plants.

The mechanism is biological: waterlogged soil goes anaerobic (oxygen-starved), killing beneficial bacteria while giving pathogenic fungi and bacteria ideal conditions. Those pathogens release enzymes that dissolve cell walls and literally liquefy plant tissue.

Early signs include soft, mushy spots on the caudex (especially at the soil line), foul odors, and sudden leaf drop despite moist soil. Advanced cases turn black or brown and can kill a plant within 1–2 weeks.

Treatment means acting fast. Unpot the plant and inspect all the tissue. With a sterilized sharp knife, cut away every soft or discolored area plus a half-inch margin into healthy tissue.

Let the wounds dry fully in open air for 2–4 weeks somewhere warm (75°F) and well-ventilated, dust with powdered sulfur once callused, then repot in completely dry pure pumice or perlite and don’t water for 1–3 months until new growth appears.

Surgery only succeeds 30–50% of the time once more than half the caudex is affected. Prevention through proper watering is 95%+ effective.

Can I water during dormancy?

Most mature plants need zero water during full dormancy, once all the leaves have dropped.

A dormant, leafless plant has no transpiration, minimal metabolism, and can’t process water, so any moisture just sits in the soil creating rot conditions.

There are exceptions. Young plants (under 3 years) may not go fully dormant and can take a light watering every 4–6 weeks even in winter. Very large specimens may need one or two light waterings during a long dormancy if they shrink noticeably (over 20% volume loss).

The diagnostic is simple: if the plant has dropped all its leaves, don’t water; if it keeps leaves through winter, keep watering but stretch to every 3–4 weeks.

What temperature range do these plants need?

They thrive at 65–85°F during active growth and tolerate brief swings from 40 to 95°F.

Most species survive a light frost (32–35°F) for a few hours but suffer tissue damage below 28°F. Year-round warmth keeps them growing but prevents natural dormancy, which over time hurts health and flowering. Requirements vary by species and native elevation: lowland coastal species want warmth year-round and show cold damage below 40°F, while highland species take cooler conditions and may need a winter chill (45–55°F) to trigger dormancy and bloom.

How cold is too cold?

For most species, 28°F is the critical threshold where cells freeze, rupturing walls and causing irreversible death.

But damage starts well above freezing. At 35–40°F many species show stress: leaf discoloration, stalled growth, and greater disease susceptibility. Indoor growers rarely hit freezing, but cold windowsills can cause localized damage, where leaves touching the glass on a subfreezing night freeze while the rest of the plant is fine.

Keep plants 4–6 inches from the glass, or add an insulating barrier on the coldest nights.

What about winter dormancy temperature?

Ideal dormancy temperatures are 50–65°F, clearly cooler than active growth but above freezing.

That range signals the dry season, reinforcing the hormonal dormancy cues while lowering metabolic rate and water need. Plants held at 70–75°F year-round may skip dormancy entirely, keeping leaves and growing slowly. That’s tolerable for a year or two but eventually causes decline as the plant misses its rest period.

Cool spots in a heated home are the challenge; options include an unheated sun porch (ideal at 45–60°F), a basement with grow lights, a garage with windows, or just the coolest room with the heat vent closed (60–68°F).

What soil mix should I use?

Use an extremely fast-draining mix: 70–80% mineral (pumice, perlite, coarse sand, crushed granite) and 20–30% organic (peat moss, coco coir, composted bark).

Standard potting soil holds too much water and rots these plants. You want a mix that drains within seconds and dries fully in 3–5 days, mimicking Madagascar’s rocky, sandy, limestone soils that hold almost no water. In nature these plants root into rock crevices, thin soil over limestone, or pure sand where water drains instantly.

A few recipes that work:

• General purpose: 3 parts pumice + 2 parts perlite + 1 part peat moss.
• Maximum drainage: 4 parts pumice + 1 part perlite.
• Seedling mix: 2 parts pumice + 1 part perlite + 1 part coco coir.

Pumice is the ingredient that does the real work in every one of these, holding water inside the stone while keeping air around the roots.

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Why does soil drainage matter so much?

Drainage controls oxygen at the roots.

Roots need oxygen for cellular respiration, the process that powers nutrient uptake, growth, and maintenance. Waterlogged, anaerobic soil kills roots within hours to days. The cascade is predictable: waterlogging displaces oxygen, root cells can’t respire, roots die and decompose, decomposition feeds anaerobic pathogens, those pathogens infect living tissue, and rot spreads from roots to caudex.

Excellent drainage breaks that chain at step one: if the soil never waterlogs, oxygen stays available and the pathogenic conditions never develop.

Can I use regular cactus soil?

Commercial cactus mixes beat standard potting soil but usually still hold too much moisture for caudex plants. Most brands run 40–60% organic matter versus the 20–30% maximum you want. They suit many American cacti but stay too wet for these extreme drought specialists.

A simple fix: buy commercial cactus mix and cut it with pumice or perlite, roughly 1 part cactus soil to 1 part pumice. Test any mix by watering and watching the drainage. Water should run from the holes within 2–3 seconds; if it takes 10+ seconds or pools on top, the mix is too dense.

How do I successfully germinate caudex plant seeds?

Use the paper towel method. Moisten a paper towel with distilled water, place seeds on one half, fold the other half over, seal in a bag or container, and hold at 75–85°F.

Check daily; sprouting takes 3–21 days depending on species. Once the radicles (first roots) reach about a quarter inch, move them carefully to individual pots with seedling mix.

Fresh seed matters enormously. Pachypodium seed loses 50%+ viability a year, so fresh seed (harvested within 6–12 months) may germinate at 80–90% while two-year-old seed drops to 30–40%. Buy from reputable specialists who date their seed lots.

For hard-coated species, pre-soak seeds in warm water (80–90°F) for 12–24 hours to soften the coat and let water reach the embryo.

What temperature and light do seedlings need?

Keep seedlings at a steady 75–85°F for the first 3–6 months; temperature swings stress them and slow growth, so a heat mat under the tray helps.

Their light needs differ from adults. While mature plants demand full sun, seedlings under 4–6 months prefer bright indirect light or filtered sun, since direct midday sun can scorch tender tissue. Give morning or late-afternoon sun (2–4 hours) plus bright shade, then ramp up direct exposure over 6–12 months.

By age one, most can take full sun like adults.

How long until seedlings develop a visible caudex?

Most Pachypodium show initial caudex swelling by 6–12 months, though that may be just a slight basal thickening rather than a true flask. Impressive form takes 5–10+ years even in ideal conditions.

Annual caudex gain averages 2–5 cm (1–2 inches) for vigorous species in good conditions, and far less for specialists; P. brevicaule may add only 0.5 cm a year, so a 4-inch plant represents 15–20 years. Set realistic expectations: a one-year-old might be 2–4 inches tall with a pencil-thin stem, a five-year-old maybe 8–12 inches with a 2-inch base, and true specimen plants take decades.

When and how should I fertilize?

Fertilize only during active growth (April–October) with a low-nitrogen formula (NPK like 2-7-7 or 3-12-6) diluted to half strength, applied monthly or quarterly.

Stop completely November–March. Always feed previously moistened soil: water thoroughly first, wait 30 minutes, then apply the diluted solution.

Nitrogen drives leafy growth, phosphorus builds roots and flowers, and potassium boosts drought tolerance. High-nitrogen feeds cause rapid vertical growth with little caudex thickening, the opposite of what you want, while low-nitrogen formulas redirect energy into storage tissue. For maximum caudex with a compact form, feed quarterly (April, June, August, October) at half strength; for moderate balanced growth, monthly April–September.

More is not better, since over-feeding causes leggy growth and salt buildup.

What happens if I fertilize during dormancy?

Dormant plants can’t use nutrients. With no leaves for photosynthesis and transpiration, uptake is minimal, so fertilizer just accumulates as mineral salts that can reach toxic levels and damage roots when growth resumes. If you fed by accident, leach the soil in early spring before growth restarts: apply plain water thoroughly, let it drain, and repeat 3–4 times in one session to flush the salts.

Should I use organic or synthetic fertilizer?

Both work. Synthetics (like a cactus-specific 2-7-7 liquid) give precise ratios for targeted caudex development. Organics (worm castings, compost tea, fish emulsion) provide slow-release nutrition with beneficial microbes but usually carry more nitrogen, so dilute them further.

Many advanced growers use a hybrid: worm castings top-dressed annually for a slow baseline, plus occasional synthetic liquid quarterly for controlled supplementation.

How do I recognize when my plant is entering dormancy?

Yellowing and dropping leaves are the main signal, usually September–November in the Northern Hemisphere.

Lower leaves go green to yellow to brown before falling, which is completely normal. At the same time growth ceases, no new leaves emerge, and the caudex may shrink slightly as stored water is used. Dormancy is triggered by shortening days and cooling temperatures: phytochrome proteins sense the shorter photoperiod and shift hormones, raising abscisic acid (the dormancy hormone) and lowering growth hormones.

That shift drives leaf senescence, where nutrients are pulled back into the caudex before the leaves drop.

Don’t fight dormancy with extra water or warmth. Forcing it produces weak, unsustainable growth and eventual decline; the rest period is biologically necessary for resource consolidation and hormonal cycling.

What should I do when dormancy begins?

Reduce watering gradually as leaves yellow. When leaves start dropping, cut watering frequency by half; when half have fallen, halve it again; when nearly all are gone, stop entirely.

Keep providing bright light even while the plant is bare, since leafless stems still do a little photosynthesis (5–10% of summer rates). Move it somewhere cooler if you can, ideally 50–65°F, and keep air moving to prevent fungal issues on dormant tissue. Dormancy usually runs 3–5 months; just leave the plant alone with light and cool temperatures.

How do I bring plants out of dormancy?

Watch for buds swelling from late February through April. When they visibly plump up, resume very light watering, just enough to moisten the top inch or two once. Wait and watch for 1–2 weeks; if growth continues, ramp watering up gradually:

• First month: water once.
• Second month: water twice.
• Third month: return to the regular schedule.

Raise temperatures to 70–75°F as growth resumes, and start fertilizing only once leaves have fully emerged and new growth is clearly active, typically April or May. Some plants delay until May in a cool spring, so wait for clear growth signals rather than forcing it with premature water.

What container should I use for caudex plants?

Choose pots just 1–2 inches wider than the current caudex, never much larger. Under-potting creates controlled root restriction that drives caudex thickening instead of excessive height.

Use unglazed terracotta in humid climates for maximum drying, or glazed ceramic in arid climates to slow drying. Every container needs at least 3–5 drainage holes of about a half inch. Match depth to the species: shallow-rooted plants like Dioscorea and Stephania want pots 4–6 inches deep, while tap-rooted Pachypodium and Adenia prefer 8–15 inches.

Matching depth to actual roots prevents dead soil volume that stays permanently wet.

Why does terracotta work better than plastic?

Terracotta’s porosity lets moisture evaporate through the walls, effectively raising the drainage rate and preventing waterlogging. That evaporation also cools the root zone 5–10°F versus plastic in direct sun, which matters because root temperatures above 95°F inhibit nutrient uptake.

The flip side: in very arid climates terracotta can dry so fast it needs daily watering. There, glazed ceramic or plastic brings watering back to a manageable level while still growing the plant well.

When should I repot?

Repot in early spring (March–April), just before dormancy breaks but after frost danger passes, so the plant can grow new roots into fresh soil and establish before summer. Repotting during dormancy leaves bare roots exposed during an inactive period, and repotting mid-growth causes shock.

Repot young, actively growing plants every 2–3 years. Mature slow growers can stay in the same pot 5–10 years, or indefinitely with annual top-dressing. When you do repot, remove the plant carefully, inspect the roots for rot or pests, prune any dead or damaged roots with sterile shears, remove 30–50% of the old soil while gently loosening the outer roots, repot at the same depth or slightly higher (exposing a bit more caudex), water lightly, and give bright shade for 1–2 weeks before returning to normal conditions.

How do I encourage thick caudex development?

Drive caudex thickening with under-potting (containers just 1–2 inches wider than the caudex), minimal water and fertilizer (mimicking harsh natural conditions), and maximum light (8+ hours of direct sun). This pushes photosynthetic resources into storage tissue rather than excessive height or root growth.

Root restriction creates a mild chronic stress that shifts hormones: raised abscisic acid signals resource scarcity, so the plant prioritizes building water-storage capacity (a thicker caudex) as insurance. In resource-rich conditions it does the opposite, racing upward with extensive roots.

Hard pruning from a young age helps too. Trim the main stem tips by 1–3 inches each year during active growth. That removes apical dominance (where the tallest tip suppresses lower growth), redirecting hormones to the base and stimulating girth.

What is the treat-them-mean philosophy?

It means giving the minimum care that keeps plants alive and slowly growing, rather than optimal care for fast growth. Water at minimum frequency (every 10–14 days in peak summer), fertilize just 2–4 times a year at quarter strength, and keep plants pot-bound.

This controlled deprivation mimics Madagascar’s harsh rocky habitats. In resource-rich conditions plants grow tall and leafy with small caudices; in resource-limited conditions, vertical growth slows and energy diverts to storage. The mechanism is carbon partitioning: under stress, more photosynthate becomes starch and storage compounds instead of cellulose for stem elongation.

Even so, set expectations: dramatic form takes 5–10+ years, with annual caudex gain of 2–5 cm for fast species and as little as 0.5 cm for slow specialists.

Can I speed up caudex development?

Not dramatically, but a few things help modestly. Maximum light (outdoor full sun May–September) increases photosynthesis, moderately frequent watering during the growing season (weekly versus bi-weekly) supports faster growth while keeping some stress, and warm year-round temperatures (70–75°F minimum) extend the season.

The catch is that rapid-growth protocols produce less attractive plants. The most impressive specimens pair reasonable size with character: interesting bark, contorted growth, an aged look, all of which come from slow growth and stress over years. Fast-grown plants often look bloated and bland despite their size.

The collector community knows this: a 10-year-old, 6-inch P. brevicaule grown hard earns far more respect than a 3-year-old, 12-inch P. lamerei raised on abundance.

Are these plants legal to buy and grow?

Yes. Nursery-propagated Madagascar caudex plants are completely legal to buy and grow in the US for a personal collection.

That said, the entire Pachypodium genus and several Adenia species are protected under CITES (Appendix II), so international trade requires permits and documentation. Domestic sales of established cultivated stock don’t need permits.

CITES protection exists because several species face real extinction threats from illegal collection and habitat loss. Pachypodium eburneum is Critically Endangered, largely from horticultural-trade poaching, and climate models project Madagascar’s threatened Pachypodium rising from 7 to 13 species, with 3 potentially extinct in the wild by 2080.

How do I verify plants are legally sourced?

Buy only from established, reputable nurseries that propagate their own stock or source from documented legal importers. Ask specific questions: Is this plant wild-collected or nursery-propagated? Can you provide import documentation if it was imported?

Legitimate sellers are transparent and happy to answer.

Red flags include vague answers about origin, defensive responses, listings advertised as “freshly imported” with no mention of permits, suspiciously low prices for rare species, and any unwillingness to provide documentation. Seeds and nursery-grown plants are far more available in legal trade than adult wild-collected specimens, and multi-generation captive-bred plants have zero wild-collection impact.

What conservation efforts exist?

Support conservation by buying only nursery-propagated plants, never wild-collected. Learn seed propagation so you become a net producer rather than a consumer, and back ethical nurseries with transparent sourcing.

Donating helps too. Organizations working in Madagascar (Missouri Botanical Garden, WWF Madagascar, Durrell Wildlife Conservation Trust) put even $10–20 a month toward field work, habitat surveys, community education, and income alternatives to poaching; many collectors set aside 5–10% of their plant budget for it. Ex-situ conservation (cultivated collections outside natural habitats) is real extinction insurance: well-documented, seed-propagated collections can be critical genetic reservoirs if wild populations collapse.

What are the most common problems and how do I fix them?

Root and Stem Rot

What to look for: Soft, mushy areas on the caudex (especially at the soil line), a foul smell, brown or black discoloration, and sudden leaf drop despite moist soil. Rot can kill a plant in 1–2 weeks.

How to fix it: Act immediately. Unpot and inspect the full extent. With a sterilized sharp knife, cut away all soft tissue plus a half-inch margin into healthy tissue; if rot has reached the central core, survival is unlikely but worth attempting.

For plants with over 50% of the caudex affected, success is under 30%. Clean wounds with 3% hydrogen peroxide, dry in a well-ventilated, warm (75°F), shaded spot for at least 2 weeks (up to 4–6 for large wounds), then dust with powdered sulfur, repot in completely dry pure pumice, and don’t water for 1–3 months until new growth emerges.

Why it works: Surgery removes the infected tissue and pathogen source, extended drying lets a protective callus form, sulfur is fungicidal and bactericidal, and a very dry mineral medium prevents recurrence while roots regrow.

Mealybug Infestation

What to look for: Small white cottony masses in leaf axils, under leaves, and around the soil line. Mealybugs breed fast (females lay 300–600 eggs that hatch in 1–2 weeks), causing yellowing leaves, stunted growth, sticky honeydew, and eventual decline.

How to fix it: Isolate the plant immediately. For light infestations, dab individual bugs with 70% isopropyl alcohol on a cotton swab, which dissolves the waxy coat and kills on contact. For heavy ones, spray thoroughly with horticultural oil or insecticidal soap every 5–7 days for 3–4 weeks to break the breeding cycle; severe cases may need a systemic insecticide.

Why it works: Alcohol strips the protective wax and exposes the soft bodies to desiccation, insecticidal soap disrupts cell membranes, and repeated applications catch newly hatched nymphs before they reproduce.

Spider Mites

What to look for: Fine yellow stippling on leaf surfaces, webbing in heavy infestations, and leaves turning bronze or brown. Spider mites love hot, dry, still air.

How to fix it: Raise humidity and air circulation as prevention. For early infestations, blast the plant with plain water every 3 days for 2 weeks. For established ones, apply insecticidal soap or a miticide every 5–7 days for 3 rounds, since eggs resist treatment and must be hit as they hatch.

Why it works: Forceful water knocks mites off physically, soap and miticides kill on contact, and repeated applications over 2–3 weeks clear newly hatched mites before they mature.

Insufficient Light Causing Etiolation

What to look for: A plant growing tall and thin, reaching toward the light, with elongated stems, wider gaps between leaves, pale or yellowish color, and a caudex that stays small relative to height.

How to fix it: Move it to the brightest spot available, outdoors in full sun (acclimate over 2 weeks) or at a south window plus grow lights running 12–14 hours a day, 6–12 inches above the plant. Prune back the leggy growth to a more proportional level, then keep maximum light with under-potting and minimal water for compact regrowth.

Why it works: Etiolation is the plant’s response to too little light, with cells elongating to seek brighter conditions. Fixing the light stops the abnormal pattern. The old stretched stems won’t thicken retroactively, but new growth comes in correctly.

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