Anyone else think our rubber plant “rules” are cargo cult gardening?
The same advice gets parroted: bright indirect, let it dry halfway, no drafts, small pots to keep it “compact,” pinch or notch to branch. I’ve been growing Ficus elastica for years and I can’t square those rules with what I see.
Observations that contradict the status quo:
- Light: After slow acclimation to very high light (outdoors summer sun or 400-800 µmol/m²/s indoors under LEDs for 6-8 hours), internodes tighten dramatically, leaves get smaller but thicker, and branching increases without any pinching. My “bright indirect” plants stay lanky no matter how perfect the watering is.
- Water: In semi-hydro with a constant reservoir and oxygenated, chunky medium, I get zero edema or leaf drop. The “they hate wet feet” line seems to conflate low oxygen with moisture.
- Pot size: Upsizing into a larger pot with coarse substrate did not cause elongated growth; it increased vigor and bud break. Root restriction didn’t make anything “compact”; it just slowed the plant.
- Notching: Success rate is wildly seasonal. I get 70-90% bud activation only when the plant is in an active push and daylength/incoming DLI is rising. In winter or under low DLI, I get callus and nothing else. Auxin dominance + carbohydrate availability seems to explain the mismatch better than the typical “just notch any time.”
- Color on ‘Burgundy’/‘Ruby’: The deep pigment only holds for me above a certain daily light integral and with a slight night drop. Anecdotally, >20-25 mol/m²/day and nights 4-8°C cooler deepen color. Warm, steady rooms fade to green even if PPFD looks decent.
Questions for the group, looking for numbers, not vibes:
- Has anyone logged bud break after notching vs heading cuts as a function of DLI and day-night temp differential? What DLI threshold predicts consistent branching for you?
- In semi-hydro, what air-filled porosity or wicking column height correlates with best root health? Anyone run dissolved oxygen or at least track reservoir turnover?
- Pot size myth: do you have side-by-sides where substrate and light are controlled but volume differs? What happened to internode length and leaf size?
- For dark cultivars, have you quantified color retention under different spectra/DLIs or with night drops? Even crude phone colorimetry or side-by-side photos with timestamps would help.
- Leaf shine and “clogged stomata” claims: has anyone done a before/after PAR reflectance or gas exchange proxy, or at least tracked growth under wiped-with-water vs commercial shine vs dusty control?
If folks are game, I propose a simple community trial for the next 8-12 weeks:
- Two matched cuttings or branches per person.
- Factor A: Light/DLI target low vs high (e.g., 8-12 vs 20-30 mol/m²/day; use a PAR app consistently, even if imperfect).
- Factor B: Notching vs heading cut vs untouched control applied when you see active extension.
- Factor C: Medium moisture regime: well-aerated soil watered when 50% dry vs passive hydro with a fixed reservoir.
- Optional: Night temperature differential small (≤2°C) vs moderate (5-8°C).
Track:
- Time to bud swell and break, number of shoots activated.
- Internode length on the next two leaves.
- Leaf thickness proxy (mass/area) or at least width/length.
- For dark cultivars, a weekly top-down photo under the same light, plus a white balance card if you have one.
I’m not trying to be contrarian for sport; I just suspect a lot of our rubber plant lore is houseplant-era extrapolation from low-light rooms. If we can anchor care to light quantity, oxygen availability, and timing relative to growth phase, we might retire a few myths. Who’s got data, logs, or even clean side-by-sides?
