FrostGuard™ - PTC Greenhouse Heater
FrostGuard™ - PTC Greenhouse Heater
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The 30-Day Frost Guarantee
Run it for thirty nights. If you're unhappy with it for any reason, message us within 30 days of delivery and we'll walk you through a return and a full refund.
- 🌡️ Digital thermostat with probe — set it, it holds it
- 🔥 3-second PTC heat — no open coil behind the grille
- 🌬️ Fan-only mode for summer — one unit, four seasons
FrostGuard™ - PTC Greenhouse Heater
What size greenhouse does it heat?
What size greenhouse does it heat?
1500W / 5100 BTU. It comfortably holds frost off a 6×8 to 8×12 ft greenhouse, a small sunroom, a shed or a grow tent. Bigger, drafty or single-wall poly spaces want a second unit. It's a frost-protection heater, not a whole-barn furnace, and we'd rather tell you that now.
How does the thermostat work?
How does the thermostat work?
Plug the heater into the included digital controller, push the probe into the soil or clip it near your plants, press SET and pick a temperature. When the reading drops below it the heater switches on; when it climbs back over, it switches off. The dial on the heater itself is a coarse backup — the controller is the one you'll actually use.
Is it safe to leave on overnight?
Is it safe to leave on overnight?
That's the whole job. PTC ceramic self-limits so the element can't run away, there's no exposed glowing wire behind the grille, and the thermostat cycles it off every time the target is met. Keep it on a flat surface off wet floors, give the intake a foot of clearance, and use a 14-gauge or heavier extension cord if you need one. It's dust-rated (IP20), not splash-rated, so keep it clear of misters.
How much does it cost to run?
How much does it cost to run?
On the 800W setting, about 14¢ an hour at the US average rate of 17¢ per kWh, and only while the thermostat is calling for heat. Most frost nights need a few hours of actual run time, not eight. Full 1500W is there for the nights that need it.
How long does shipping take?
How long does shipping take?
Please allow about a week for processing. Need it before a cold snap? Choose Expedited Shipping at checkout. You can follow your order from our track-order page or by emailing us.
Set 45°F. Go to Bed.
Every greenhouse heater you've owned ran until you walked out and turned it off. FrostGuard runs until the number you picked is met. Plug it into the included digital controller, push the probe into the soil beside your seedlings, press SET and choose a temperature. When the reading dips below it, the heater switches on and blows 3-second PTC heat across the bench. When it climbs back over, it switches off and waits. You find out in the morning, from the display, that it cycled eleven times and nothing froze.
No Open Coil. No Fuel. No 3am Checks.
Most cheap heaters put a glowing red wire behind a thin grille and hope nothing blows into it. Propane puts an open flame in a room full of dry leaves and a door that won't zip shut. FrostGuard is built the other way around. The heat comes from a PTC ceramic block that self-limits — it physically can't run away — and the front grille hides it behind a mesh fine enough to keep moths and dust out. Alloy steel body, ETL listed, and a thermostat that cuts the power the moment your target is met. Honest limit: it's dust-rated, not waterproof. Keep it off wet floors and away from misters.
One Heater, Four Seasons
The heaters that only earn their keep four months a year end up in the shed by April. FrostGuard has a fan-only mode that moves 198 m³ of air an hour with no heat at all, so in July it's the thing keeping your tent from cooking. Three settings on one knob: fan, 800W for most frost nights, 1500W for the ones that mean it. Under five pounds, a carry handle on top, and a tilt-adjust steel stand so you can aim it at the bench instead of the roof.
WHO IT'S FOR
Four growers, one heater
Hobby greenhouse owners, overwinterers, seed starters and grow-tent growers buy it for different reasons. It answers all four.
“I lost a whole tray of seedlings to one cold night.”
You didn't miss anything; the heater just had no way of knowing. FrostGuard reads the temperature at the probe, right beside the plants, and restarts itself the moment it drops below your number.
“Propane got expensive and I’m sick of refilling it.”
No tank, no trips, no flame. Plug it in, set it to 800W, and it costs about 14¢ an hour only while it's actually running. Most frost nights that's a few hours, not eight.
“I don’t trust a heater running while I sleep.”
Neither did we. PTC ceramic self-limits so it can't overheat, there's no exposed coil behind the grille, and the thermostat cuts power every time the target is met. ETL listed, alloy steel body.
“My tent cooks in summer and freezes in winter.”
Same unit, both problems. Fan-only mode in summer keeps air moving with no heat; 800W in winter holds the line. Under five pounds and a tilt stand, so it goes wherever the problem is.
THE WHOLE CASE
Four reasons, and that's the lot
One heater, one digital thermostat, and a probe you leave beside your plants.
Everything in the box
SEE IT WORK
HOW IT WORKS
Set. Probe. Sleep.
Most greenhouse heaters run until you turn them off. FrostGuard runs until the number you picked is met.
Step 1 — Set your temperature
Plug the heater into the digital controller, press SET and use the arrows to pick your number in °F or °C. Most growers land on 40–45°F for frost protection. The display shows the live reading at the probe.
Step 2 — Place the probe
Push the probe into the soil or clip it at plant height — not at the roof, where it’s always warmer. The controller reads exactly where your plants live.
Step 3 — It handles the night
When the probe drops below your number the heater switches on and PTC ceramic reaches full heat in about three seconds. When it climbs back over, it switches off. You wake up to the display, not to frost.
YOUR FIRST NIGHT
From box to first frost
What setting it up looks like, start to finish.
Plug it in
Heater into the controller, controller into a 15A outlet or a 14-gauge extension cord. Set the knob to 800W for a normal frost night.
Set the number
Press SET, pick your temperature, choose °F or °C. Forty degrees keeps most plants alive; forty-five keeps them comfortable.
Place the probe
Soil or plant height, near the coldest corner. Give the heater a flat surface and a foot of clearance in front.
Check it in the morning
The display shows the live temperature. The heater cycled itself all night. The plants didn’t notice anything happened.
THE HONEST COMPARISON
Only one does all three
The 30-Day Frost Guarantee
Run it for thirty nights. If it isn't holding the temperature you set, or you're unhappy with it for any reason, message us through the Contact page within 30 days of delivery and we'll walk you through a return and a full refund.
Set It. Probe It. Sleep.
★ [RATING]/5 · Over [N] greenhouses kept warm — set a temperature, it holds it · 3-second PTC heat, no open coil · free digital thermostat · 30-Day Frost Guarantee
ANY LAST QUESTIONS?
The things people ask before they order
What size greenhouse does it heat?
1500W / 5100 BTU. It comfortably holds frost off a 6×8 to 8×12 ft greenhouse, a small sunroom, a shed or a grow tent. Bigger, drafty or single-wall poly spaces want a second unit. It's a frost-protection heater, not a whole-barn furnace, and we'd rather tell you that now.
How does the thermostat work?
Plug the heater into the included digital controller, push the probe into the soil or clip it near your plants, press SET and pick a temperature. When the reading drops below it the heater switches on; when it climbs back over, it switches off. The dial on the heater itself is a coarse backup — the controller is the one you'll actually use.
Is it safe to leave on overnight?
That's the whole job. PTC ceramic self-limits so the element can't run away, there's no exposed glowing wire behind the grille, and the thermostat cycles it off every time the target is met. Keep it on a flat surface off wet floors, give the intake a foot of clearance, and use a 14-gauge or heavier extension cord if you need one. It's dust-rated (IP20), not splash-rated, so keep it clear of misters.
How much does it cost to run?
On the 800W setting, about 14¢ an hour at the US average rate of 17¢ per kWh, and only while the thermostat is calling for heat. Most frost nights need a few hours of actual run time, not eight. Full 1500W is there for the nights that need it.
Does it work in a grow tent?
Yes — that's one of the most common places it ends up. Set the probe at plant height, run it on 800W, and switch to fan-only mode in summer to keep air moving without adding heat.
What if it doesn't work for us?
Message us through the Contact page within 30 days of delivery and we'll walk you through a return and a full refund. No forms, no restocking fee.
How long does shipping take?
Please allow about a week for processing. Need it before a cold snap? Choose Expedited Shipping at checkout. You can follow your order from our track-order page or by emailing us.