Best Greenhouse Thermometer 2026: Min/Max, Bluetooth & WiFi Monitors Compared

Quick Answer: The best greenhouse thermometer for most growers in 2026 is the TempPro (formerly ThermoPro) TP357 — $12.99, accurate to ±1.0°F and ±2% RH, with a 260-foot Bluetooth 5.0 link so you can check the greenhouse from the kitchen. Choose the Govee H5179 (WiFi, ±0.54°F, app alerts, 328-foot WiFi range) if you need to know about a frost while you are away from home, and the water-resistant SensorPush HT.w ($64, plus the $99 G1 gateway for remote access) if the sensor has to survive years of condensation. The spec that actually separates these products is not accuracy — it is operating range: AcuRite’s own listing puts the popular 00613 at 32–122°F, which excludes both a freezing night and a sealed greenhouse in July.

A greenhouse thermometer is the cheapest insurance in the entire hobby. A $13 device tells you whether your unheated house held above freezing last night, whether the vent is opening early enough, and whether the humidity that keeps killing your seedlings is your imagination or 90% RH. Almost every roundup of these devices compares them on accuracy, which is the one spec where every model is already good enough. Here is what actually matters.

Greenhouse thermometers by the numbers:

• 32–122°F — the indoor temperature range AcuRite publishes for its widely sold 00613 monitor. A Zone 5 greenhouse drops below the bottom of that range most winter nights, and a closed greenhouse on a sunny afternoon can push past the top of it. Compare the -58°F to 158°F range TempPro lists for the TP49.
• ±0.54°F — the temperature accuracy Govee publishes for the H5179, using a Swiss-made sensor, against ±2°F on AcuRite’s classic 00613. Both are far tighter than the error introduced by hanging a sensor in direct sun.
• 49 feet vs 328 feet — Govee’s own published Bluetooth and WiFi ranges for the same H5179 unit. That gap is the whole argument for WiFi: Bluetooth range dies at the back door, WiFi reaches your phone at work.
• $163 — the real cost of true remote monitoring with SensorPush: $64 for the HT.w sensor plus $99 for the G1 WiFi gateway, per SensorPush’s pricing. Budget for the gateway or the sensor is a local-only device.
• 18–24 months — battery life TempPro quotes for the single AAA in the TP49, and SensorPush quotes “typically over 2 years” for the HT.w. A greenhouse sensor you have to recharge monthly will not get monitored.

Greenhouse thermometers compared

1. TempPro TP357 (formerly ThermoPro) — Best Overall

A sensor this cheap arrives fast enough to be in the greenhouse before the next cold snap — a free 30-day Amazon Prime trial covers the two-day shipping on a $13 order that would otherwise cost more to ship than to buy. Sponsored link — we may earn a fee if you sign up. No extra cost to you.

The TP357 is the one we recommend to almost everyone because it fixes the actual problem with a $10 thermometer: you have to walk to it. At 260 feet of Bluetooth 5.0 range, the greenhouse at the bottom of a suburban garden is comfortably inside the radius, so you check overnight lows from the kitchen with a phone instead of putting boots on. The app keeps the history, which is how you learn your own site — that the house holds 8°F above ambient on a clear night, or that the vent opens two hours too late.

What it will not do is tell you anything while you are at work. Bluetooth is a line-of-sight link between the sensor and a phone that is physically nearby; leave the property and the log simply pauses until you return. If a frost that arrives at 3am on a Tuesday while you are away would cost you a season of seedlings, read the Govee entry below instead. For everyone else, this is a $13 device that does 90% of what a $163 system does.

2. TempPro TP49 — Best Budget & Multi-Pack

The TP49 is the model that quietly proves the point of this entire page. It is one of the cheapest units in the category, and it is rated from -58°F to 158°F — a wider working range than monitors costing twice as much, because its maker specified it for outdoor use rather than for a living room. That single number is why it belongs in a greenhouse and why some better-reviewed indoor units do not.

Buy it in a multi-pack. Temperature in even a 6x8 greenhouse is not one number: the floor near the door and the top shelf under the roof can differ by 10°F or more on a sunny afternoon, and a single sensor tells you about exactly one of those places. Two or three TP49s — one at seedling height on the staging, one at floor level, one near the heater — costs less than one mid-range unit and tells you far more.

3. Govee H5179 — Best WiFi Alerts

This is the cheapest honest answer to “tell me before my plants die.” Because the H5179 connects to your home WiFi rather than to a nearby phone, the alert travels — a stuck vent on a 95°F afternoon or a heater that quit at 2am reaches you wherever you are. Set the high threshold a few degrees under whatever your crop tolerates and the low one a few degrees above freezing, and the device stops being a display and starts being an alarm.

The constraint is coverage, and it is worth checking before you buy: the greenhouse has to sit inside your home WiFi footprint. Govee publishes 328 feet in open areas, but polycarbonate walls, a garden fence and the far side of a brick house all subtract from that. If your router does not reach the greenhouse, no WiFi sensor of any brand will work there, and you need either a mesh node in the garden or the gateway-based SensorPush system below.

4. SensorPush HT.w + G1 Gateway — Best Premium

SensorPush is what you buy when the contents of the greenhouse are worth more than the monitoring kit. The HT.w is the only sensor on this page that is designed to be rained on, which matters more than any accuracy figure — a greenhouse in March runs water down the inside of the glazing every morning, and that is what kills cheap electronics. Two years of battery life and a genuinely tight sensor make it something you install and forget.

Be clear-eyed about the price, though. The sensor is $64 and the G1 WiFi gateway is another $99, so remote monitoring starts at $163 — more than twelve times the TP357. Without the gateway the HT.w is a Bluetooth device with the same fundamental limitation as the $13 unit. It earns the money in a heated year-round house, an orchid collection or a propagation setup where one failed night is expensive; it does not earn it protecting a tray of tomato seedlings.

5. TempPro TP359 — Best Display

The TP359 is the TP357 with the two upgrades that matter in practice: a much larger backlit screen and a Sensirion sensor. The screen is not vanity. Greenhouse checks happen at dawn and at dusk, in the rain, without reading glasses, and a 3.5-inch backlit display tells you the overnight minimum from the doorway rather than requiring you to pick the unit up.

Whether the accuracy upgrade from ±1.0°F to ±0.9°F is worth eight dollars is a fair question, and honestly it is not — that difference is invisible against a sensor mounted six inches too high. Buy the TP359 for the display and treat the sensor as a bonus.

6. Mercury-Free Analog Min/Max Thermometer — Best No-Battery Backup

There is a real argument for keeping one analog min/max thermometer on the wall regardless of what else you own. It has no battery to die in January, no app to be discontinued, and no pairing to lose — and when a digital reading looks implausible, it is the second opinion that settles it. Modern versions use a patented mercury-free fluid rather than the mercury units your grandfather had, so a breakage is a cleanup rather than a hazmat event.

It also does the one job that gave this category its name honestly. Reset it in the evening, read it at breakfast, and you know exactly how cold the greenhouse got — no phone, no account, no subscription. What it cannot do is warn you, which is why we list it as a backup rather than a primary.

7. AcuRite 00613 — Best for a Propagation Bench

We include the 00613 because it is genuinely good at a job — just not the job its many “best greenhouse thermometer” placements claim. AcuRite lists it with a 32 to 122°F indoor operating range, which means the two readings a greenhouse owner most wants are the two it is not specified to give you: how far below freezing the house fell, and how far past 122°F it climbed with the vent shut.

Where it belongs is indoors, over a seedling heat mat on a propagation bench, where 32–122°F covers everything that will ever happen and the humidity readout is genuinely useful for judging when to take the dome off. At around $13 with a 1-year warranty, it is a good product being sold into the wrong room.

How to choose a greenhouse thermometer

Work through it in this order:

1. Check the operating range first, not the accuracy. Anything rated for a living room — commonly 32–122°F — cannot report the two events that matter. Look for a bottom end below 0°F and a top end above 140°F.
2. Decide whether you need a record or an alarm. Min/max tells you what happened; only a WiFi sensor or a gateway-equipped system tells you while it is happening. If losing a night’s crop is expensive, pay for the alert.
3. Check that your signal actually reaches. Bluetooth realistically covers a garden (260 feet on the TempPro units); home WiFi may or may not reach the greenhouse at all. Verify coverage at the greenhouse door before you buy a WiFi model.
4. Assume condensation. Unless a sensor is explicitly water-resistant, mount it under the bench, out of drip lines, and expect to replace it every few seasons.
5. Buy two cheap ones before one expensive one. A single sensor describes a single spot. Bench height and floor level in the same house can differ by 10°F on a sunny afternoon.
6. Mount it in shade, at canopy height. A sensor in direct sun is the most common reason a greenhouse thermometer “reads wrong,” and no accuracy spec can compensate for it.

A thermometer tells you the problem; it does not solve it. Once you can see what your greenhouse is doing, the fixes are an automatic vent and circulation fan for the highs, shade cloth for midsummer, and a greenhouse heater for the lows. Still choosing the structure itself? Start with our greenhouse kit guide.