This Little Probe Does the Checking.
Five reasons growers are learning that where the temperature gets read decides whether the plants make it — and why the heater that wins is the one that reads it beside the leaves, not inside its own hot box.
A Thermostat Is Only as Good as the Spot It Reads.
Every heater that "holds a temperature" is answering one question over and over: how warm is it right here? The answer it gets depends entirely on where "here" is.
Read the temperature in the wrong spot and the heater does exactly the wrong thing with total confidence. It shuts off while the plants are freezing, or runs all night while they cook. The control works perfectly. It's just controlling the wrong air.
That's why FrostGuard's thermostat doesn't live inside the heater. It reads through a probe on a cable you put wherever the plants are: in the soil, at the bench, at the canopy, by the roost. Whatever the probe reads is what the heater answers to.
A Built-In Sensor Reads the Heater's Own Hot Air. The Far Bench Pays for It.
Heaters with a thermostat built into the housing have a sensor sitting a few inches from their own element. When the heater fires, that sensor gets the warmest air in the whole greenhouse first.
So it hits its number fast and shuts off, satisfied, while the bench at the far wall hasn't warmed at all. Then the cycle repeats: short bursts of heat near the heater, frost on the seedlings across the aisle.
FrostGuard separates the two jobs. The heater makes the heat. The probe, out at the plants, decides when there's been enough. Put it on the far bench and the heater keeps going until the far bench is at your number.
Warm Air Rises. Your Seedlings Don't.
The second wrong spot is up high. On a cold night the peak of a small greenhouse runs noticeably warmer than the bench, so a thermometer hanging from the roof frame tells you everything's fine while the trays below it freeze.
The same goes for a wall-mounted thermostat at eye level, or a smart sensor sitting on a shelf. They read the air you see, not the air the plants sit in.
The probe fixes this by going down to them. Push it into the soil, clip it to the bench edge, or stake it at the canopy. When the display says 45, it means 45 at leaf height.
Where to Put It. Two Minutes That Decide the Whole Winter.
The rule: put the probe at the height of the most fragile thing you're protecting, in the coldest spot you've got. Then four things to avoid.
| Setup | Put the probe |
|---|---|
| Greenhouse, seedling trays | In the soil of a tray on the bench farthest from the heater |
| Overwintering pots | In the pot of your most tender plant, near the glass side |
| Grow tent | Staked at canopy height, in the middle of the plants |
| Chicken coop | Near the roost, where the hens sleep |
| Garage or shed | At the height of what you're protecting, away from the door |
| Avoid | Because |
|---|---|
| The heater's airflow | It reads hot blowing air and shuts off early |
| Direct sun | Morning sun on the tip reads warm while the bench is still cold |
| Touching glass or metal | It reads the cold surface, not the air |
| Up near the roof | Warm air pools there and hides the cold below |
One Probe, Any Space. $79.95, Thermostat Included.
Because the decision lives in the probe, the same kit works in a 6×8 greenhouse, a 4×4 tent in a cold garage, a lean-to full of citrus, or a coop. Move the heater, move the probe, set a new number.
$79.95 during the Fall Sale, down from $159.90, with free shipping. In the box: the 1500W / 5100 BTU PTC ceramic heater with its fan / 800W / 1500W knob and tilt stand, the digital thermostat controller, the probe on its cable, and the manual. Overheat protection, steel body, ETL listed.
It only draws power while the probe reads below your number, so a typical cold night is a few hours of heat, not eight. Sized honestly: one unit covers a small greenhouse, tent, coop or one-car garage. Bigger space, two units and two probes.
A 1500W PTC ceramic heater with the thermostat moved where it belongs: out of the heater and onto a probe beside your plants. It reads the air that matters and holds the number you set, all night.
Why 50% off? It's our Fall Sale, priced for growers who want the probe placed and tested before the first hard frost, not the night of it.
$79.95 during the Fall Sale, half off with free shipping and 30 nights to change your mind. A probe that reads at leaf height, a number you set once, and a heater that answers to the coldest bench, not its own hot air.
Get FrostGuard — 50% Off →