Aloe: what your moisture meter reading means

The healthy band for an aloe, on whichever scale your meter prints — and, more usefully, what the same number means in different situations.

Percent (0–100)

10–35%

what the four-in-one we recommend prints

Ten-point probe (1–10)

1–4

if your probe prints a bare 1–10 sweep

Analog dial

1–2

Dry to Moist — of 4 zones

That is the band you are aiming for, not a target to hit exactly. These ranges are published horticultural consensus and are deliberately banded wide — these are unpowered galvanic probes, two of them in the same pot routinely disagree, and fertilizer salt raises the reading with no extra water present.

Got the plant in front of you? Point your camera at it — Plant Tender names what is in the pot from one photo and gives you the numbers it wants. No account, no card.

What each reading means for an aloe

An aloe wants water below 10% and starts staying wetter than it likes above 35%. If your probe prints a bare 1–10 sweep instead of a percentage, that works out like this.

Reading	For this plant	What to do
1	In the healthy band	Inside the healthy band. Leave it — the useful question is whether this number is falling since last time.
2	In the healthy band	Inside the healthy band. Leave it — the useful question is whether this number is falling since last time.
3	In the healthy band	Inside the healthy band. Leave it — the useful question is whether this number is falling since last time.
4	Wetter than ideal	Wetter than ideal. Fine a day or two after watering; a concern if it has been a week.
5	Wetter than ideal	Wetter than ideal. Fine a day or two after watering; a concern if it has been a week.
6	Wetter than ideal	Wetter than ideal. Fine a day or two after watering; a concern if it has been a week.
7	Saturated	Saturated. If this has not fallen in several days, check drainage before you change anything else.
8	Saturated	Saturated. If this has not fallen in several days, check drainage before you change anything else.
9	Saturated	Saturated. If this has not fallen in several days, check drainage before you change anything else.
10	Saturated	Saturated. If this has not fallen in several days, check drainage before you change anything else.

Every row here is worked out from this plant's own numbers — an aloe at 4 and a snake plant at 4 are in genuinely different situations.

The number depends on your soil, and most charts ignore that

An aloe is usually in gritty cactus mix, often in terracotta — sand, pumice and perlite with little organic matter.

An aloe's whole healthy band sits at the bottom of the meter. On a 1–10 probe a 1 is healthy and a 4 is already too wet, which is the reverse of how most people read the scale. There is also no reading low enough to mean water: gritty mix barely conducts between the probe pins, so an aloe that needs a drink and one that still has water at its roots can print the same 1. The meter's real job on this plant is catching the pot that stays too wet. The leaves tell you when it is thirsty.

Adjusting for your mix

Gritty mix in terracotta: readings sit at 1 or 2 most of the time and fall back to the bottom within days of a soak, so judge by the leaves. Gritty mix in plastic: the pot holds water noticeably longer, so check that the reading has come back down before you water again. Dense nursery soil, which is how many aloes are sold: readings are honest, but the pot can hold a 4 or 5 for weeks, and that is the setup that rots them. Repot into gritty mix, in a pot that is wider than it is deep.

Plant Tender asks which of these your pot is in — dense potting soil, chunky aroid mix, bark / orchid mix, semi-hydro / pon, succulent / cactus grit — and applies the adjustment for you, along with a probe-depth target from your pot size.

Where to put the probe

Halfway down, near the pot wall, away from the base of the leaves and any pups. Aloe roots spread outward more than down, so take a second reading near the bottom of the pot as well. If the middle reads 1 but the bottom still reads wet a couple of weeks after watering, the pot is deeper than the roots can use, and that wet bottom layer is where rot starts. Keep the probe clear of the leaf bases, which bruise easily.

How an aloe actually fails

Rot at the base, where the leaves join the stem. The lower leaves go soft, brown and slightly see-through, starting at the bottom, and a rotting leaf pulls away with almost no effort. Compare that with a thirsty aloe, whose leaves get thinner and curl inward along their length like a shallow channel but stay firm and attached. There is a third look that gets mistaken for both: leaves that flatten out and flop sideways instead of growing upward. That is too little light, and it is the most common complaint about aloes kept indoors.

Common situations

My aloe reads 1 — does it need water?

Not on that number. For an aloe, 1 sits inside the healthy band: the target is roughly 10–35%, which is the bottom few marks of any 1–10 probe, and gritty mix reads low even with water in it. Look at the leaves instead. Plump and firm means leave it alone; leaves that have thinned and started to curl inward mean it is time for a thorough soak. After a deep watering, most aloes indoors go two to four weeks before they need another.

My aloe reads 4. Is that dry enough to water?

It is the opposite of dry. On this page a 4 is wetter than ideal: the same number that tells a calathea owner to water tells an aloe owner to stop. If you watered in the last day or two, a 4 is expected and should fall. If it has read 4 for more than about a week, the pot is holding too much water, and the usual causes are dense nursery soil, a pot with no drainage hole, or a pot much deeper than the roots. Let it dry out fully, and repot into gritty mix if the number will not come down.

The leaves are flopping over but it reads 2.

A 2 is in the band, so this is not a watering problem. An aloe whose leaves flatten and splay outward is reaching for light it is not getting. Move it to the brightest window you have, and do it over a week or two rather than all at once: an aloe moved straight from a dim room into strong sun can scorch, and its leaves turn reddish-brown. Check the base as well. If the leaves are also soft and see-through where they meet the stem, that is rot, and more light will not fix it.

One reading can't be trusted. How fast the pot dries out can.

Everything above is really one argument: a single number from a cheap conductivity probe is not a measurement, it is a data point with a large error bar. Fertilizer salt raises it. Air gaps in chunky mix lower it. Probe depth moves it several points. Two meters in the same pot disagree.

What survives all of that is the trend. The same meter, in the same spot, in the same pot, read over a few weeks, tells you how fast your aloe in this specific mix in this specific room actually dries — and that is the thing that answers "do I water it", which no chart can do for you.

Stop looking it up. Point your camera at your aloe.

The bands above are for aloe in general. Plant Tender gets there from a photo instead: one shot of what is actually in the pot, and it names the plant and gives you the soil-moisture, soil-temperature and light numbers that plant wants. Your first scan needs no account and no card.

Scan a plant — free, no account

Already know what it is? Save it to Plant Tender and it remembers what your aloe read last time, then tells you water or leave-it-be — so you are reading a trend instead of interpreting one number in isolation. Free for your first three plants.

Ranges come from Plant Tender's per-species dataset, which is version-controlled and reviewed in public — Aloe vera, 10–35% moisture, 51–83°F soil temperature, bright direct light.