Grow Lights for Alocasia

We have not tested these fixtures. What follows is published specification, Extension guidance, and our arithmetic joining the two, with the working shown.

“Bright indirect light” is the phrase attached to alocasia everywhere, and it is the least actionable advice in houseplant care. It contains no quantity and no distance. This page replaces it with a band, a fixture size and a hanging height.

The target

Iowa State University Extension puts foliage and flowering houseplants at 6 to 10 mol/m²/day. Alocasia belong at the upper half of that band: they are understory aroids, but large-leaved ones that put real energy into each new leaf, and they are noticeably more demanding than a pothos or a heartleaf philodendron.

What “indirect” is actually warning about is not intensity so much as exposure — direct midday sun through glass scorches those thin leaves. A grow light at a sensible distance is diffuse by comparison, which is why alocasia often do better under a fixture than on a south sill.

1. SANSI 36W BR30 — one alocasia, placed by numbers

65.6 µmol/s published, with a PPFD of 265.58 µmol/m²/s at a stated one foot. The stated distance is the reason this is first: alocasia are sensitive to getting this wrong in both directions, and a bulb you can place by arithmetic removes the guesswork.

The downside: one bulb lights one plant, and alocasia are collected in groups more often than most. It also runs 36 W, which is four times the draw of the 9 W bulbs and about $2.38 a month at 12 hours.

2. AC Infinity IONBOARD S22 — a shelf, dimmed down

A 115 W board publishing 2.7 µmol/J, which implies about 311 µmol/s, over a stated 2 ft by 2 ft coverage. On its own that is far too much light for this plant — and it dims in 20% increments, which is what makes it the right answer for a group.

The downside: you are buying a fixture and then using a third of it, which is a strange purchase unless you also grow higher-light plants or plan to. AC Infinity also publishes a “1098 PPFD” figure with no measurement distance attached, which makes that particular number unusable — we derive from the wattage and efficacy instead.

3. GE Grow BR30 — a small plant, cheaply

16 µmol/s per bulb from 9 W, CRI 90, sold in a two-pack. For a young alocasia — a polly, a small zebrina, anything under a foot — 16 µmol/s from a foot away is the right order of magnitude rather than a compromise, and two bulbs cover two plants.

The downside: it will not carry a mature plant. The 32 µmol/s figure above is two of these bulbs’ entire output with nothing lost to spill, and GE publishes no beam angle, so what actually reaches the leaves cannot be computed — only bounded.

Reading the plant

Alocasia are unusually expressive about light, which makes them easier to tune than most plants on this site.

• Too little: long petioles reaching upward and leaning, new leaves arriving smaller than the ones before them, and the plant dropping an old leaf for every new one so the total never increases. That last pattern is the clearest signal, and it is usually read as normal shedding.
• Too much: pale or bleached patches on the upper surfaces facing the fixture, silvering between the veins, and crisp brown margins on the newest leaves. Raise the fixture or dim it.
• Not a light problem: yellowing lower leaves with damp soil, which is watering; small brown spots with yellow halos, which is not something a fixture fixes; and a dormancy in winter where the plant dies back to the corm, which is normal for several species and not a sign the light failed.

Hours

Iowa State University Extension gives 12 to 14 hours as the general range for indoor plants, with 10 as a floor and 16 as a ceiling. Twelve is what every calculation on this page assumes, and it is the right default here.

If an alocasia is short of light, lengthening the day to 14 hours adds about 17% to the daily total without raising the intensity the leaves see — which for a plant that scorches is the safer of the two levers. The other lever, moving the fixture closer, works but should be done in steps of a few inches with a week between them.

Running cost

Sizing by the plant you actually have

“An alocasia” ranges from a four-inch polly to a five-foot zebrina, and the fixture that suits one is wrong for the other. The target band does not change; the area it has to cover does.

The pattern worth noticing is that a single 36 W bulb publishing 65.6 µmol/s covers everything up to a large plant, and stops there. Beyond that the answer changes shape rather than getting bigger: a board or a pair of bars, not a brighter bulb.

Supplementing a window instead of replacing it

Most alocasia live near a window and need help for part of the year rather than a full artificial day. That changes what you should buy.

A supplement has a smaller job than a replacement, so the bulb that would be marginal as a sole source is often exactly right alongside an east or north window. It also changes the schedule: run the fixture during the darkest hours at each end of the day rather than through the middle, when the window is already doing the work.

The one arrangement to avoid is a fixture directly opposite a bright window with the plant between them. Alocasia lean hard toward the strongest source, and two competing sources at similar strength produce a plant that twists between them. Put the fixture above the plant and let the window come from the side.

Winter, and why the plant may stop

Several alocasia species slow dramatically or die back entirely to the corm in winter. This is normal, and it is the single most common reason people conclude their new grow light has failed.

A grow light holds the daily light integral steady through a dark season, which genuinely helps a plant that would otherwise decline. It does not override dormancy, because dormancy in these species responds to temperature as well as light. A plant in a 60 °F room in January will slow whatever the fixture does.

The practical approach is to keep the light on its normal schedule, reduce watering to match the reduced growth, and wait. A corm that looks firm is alive. Increasing the light to force growth through a dormancy wastes electricity and risks scorching leaves the plant is already withdrawing resources from. The wider winter case is in how much light houseplants need in winter.

Moving a plant under a light without shocking it

An alocasia bought from a shop has been grown under whatever that shop had, usually far less light than a grow light delivers. Its existing leaves are built for that level and cannot rebuild themselves.

Putting such a plant straight under a fixture at its final height produces bleaching within days, which is read as proof that alocasia hate grow lights. It is not: it is a transition injury, and new leaves grown under the new level arrive adapted to it.

If you only buy one fixture

Most people reading this own one alocasia and will buy one light, so the honest single answer matters more than the ranked list.

Buy the 36 W bulb with the published one-foot PPFD, and hang it 15 to 18 inches above the plant. It is the only pick here that can be placed by arithmetic rather than guesswork, it covers every plant size up to a large mature specimen, and at about $2.38 a month it is cheap to run. The board is the better purchase only if you already know you are building a shelf, and the 9 W bulbs are the better purchase only for a plant that is genuinely small and likely to stay that way.

Corms, offsets and lighting the young plants

Alocasia multiply by corms, and anyone who keeps one for a year ends up with small offsets to grow on. They want different treatment from the parent, and getting it wrong is the commonest way people lose them.

A potted corm with no leaves has no way to use light at all, and no way to replace water lost to it. Until the first leaf unfurls, the corm needs warmth and moisture rather than intensity, and putting it under the fixture that suits the parent plant dries the medium out faster than the corm can root into it.

The practical arrangement is a shelf where the parent sits directly under the bulb and the offsets sit at the perimeter, moving inward as they put out their second and third leaves. That uses the falloff you are usually fighting as a feature.