The best plant heaters, compared.
Top pick: RC SLL 18 W heat mat Best value: HBN 17.5 W seedling mat – About £14.99 with 4.6 from 283 reviews, the lowest shelf price at 4.4 or above with at least 200 reviews. Updated October 2026.
A plant heater on amazon.co.uk is one of four tools: a seedling heat mat, a heated windowsill propagator, a low-watt tube or convector for frost, or a ducted grow-tent heater. You are usually protecting seed trays, a windowsill, or tender plants in a greenhouse, and the Royal Horticultural Society treats those jobs separately. Look for a setpoint you can change, a 220–240 V supply with a BS 1363 plug, and an IP code that matches how wet the place is. The order of those checks is in the [plant heater buying guide](/hub/plant-accessories/plant-heater/sub/plant-heater-buying-guide). An unregulated PVC mat, often about 25 by 50 cm and 17.5–20 W, sits under a seed tray. The three-bay unit is 12 W, about 16–19°C, with a stated UK plug and 220–240 V, and no adjustable thermostat. An air heater is for when the greenhouse itself must stay above freezing.
A plant heater on amazon.co.uk is one of four tools: a seedling heat mat, a heated windowsill propagator, a low-watt tube or convector for frost, or a ducted grow-tent heater.
38 products checked · 61 hrs invested · +18,400 readers
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Personal buying guide
Question 1 of 2
What are you warming?
The RC SLL BHD-100 is an 18 W PVC mat at about £42.99, with a claimed 20–30°C band and no thermostat in the box. A bullet recommends a separate RC SLL thermostat. Voltage is not printed. The title says a 4 pack and a bullet says one pad, so the count is not a fact here. Dimensions are 52.71 by 1.27 by 25.4 cm and 1.84 kg. amazon.co.uk shows 4.7 from 46 reviews, with 13 stored texts. Buyers who received working mats liked the thicker plastic. One report says one mat in a pack of four failed after about three weeks. A 4.7 from 46 reviews does not outrank the EarlyGrow count of 304.
Pros
Cons
Best for: A seed tray if you already own a thermostat and you check how many pads are in the box
Less suitable: Anyone who needs a settled pack count or a printed voltage
Specifications
Common questions
How many mats are in the box?
The title says a 4 pack and a bullet says the package includes 1 pad. The count is not settled here.
Is a thermostat included?
No. A bullet recommends an RC SLL thermostat, and that thermostat is not in the included line.
Why is 4.7 not the top pick?
The star line is 4.7 from 46, with 13 stored texts. The EarlyGrow propagator has 4.5 from 304, which is the larger count at 4.4 or above.
The HBN CP-C93 is a 17.5 W seedling mat at about £14.99, with 230–240 V printed and a claimed band of about 24–30°C that is not a dial. The mat is described as about 10 by 20 inches. Waterproof is wording only, with no IP code. amazon.co.uk shows 4.6 from 283 reviews. The first 50 texts praise plug-in use under tomato and pepper trays and a low price. They also say there is no timer, heat can be uneven, and one mat stopped after one or two months. It is the best value here because it is the lowest shelf price at 4.4 or above with at least 200 reviews. It will not frost-proof a greenhouse.
Pros
Cons
Best for: A windowsill seed tray when you want a low price and a large review file, and you can switch it off yourself
Less suitable: A greenhouse frost watch, or anyone who wants a setpoint
Specifications
Common questions
Can you set the temperature on the HBN 17.5 W mat?
No. The listing claims about 24–30°C and prints no dial. Reviews say there is no temperature control and no timer.
What size is printed?
The listing states 10 by 20 inches, which it also gives as 25 by 50 cm. The package line is 26.5 by 7.2 by 7.2 cm.
Is a waterproof claim the same as an IP code?
No. This listing says waterproof and says you can wipe it. It does not print an IP code, and it does not claim you can immerse it.
The AOOWU JX02 is about £18.99, with a controller claimed from 20°C to 45°C and IPX4. The title size is 52.5 by 25 cm. Wattage and voltage are not printed, so the listing does not show whether the supply is 230 V. The listing says indoor use and not to immerse the mat. amazon.co.uk shows 4.6 from 11 reviews, and seven stored texts mention rose cuttings and seeds, with one disappointed review and no repeated hardware fault. A 4.6 from 11 is a thin sample next to the HBN mat’s 283 reviews.
Pros
Cons
Best for: One indoor propagator if a stated IPX4 controller matters more than a known wattage
Less suitable: Anyone who needs to confirm 230 V and a wattage before they buy
Specifications
Common questions
What temperature range is printed?
The controller is claimed from 20°C to 45°C. A separate line describes roots at 20–30°C. The seven stored texts do not show how close the probe stays to the setpoint.
What is the wattage?
It is not printed in the product data. Voltage is not printed either, so you cannot check the UK supply from the specification block.
Is IPX4 the same as a waterproof greenhouse heater?
IPX4 is a splash rating. The listing says do not immerse the mat, and it says indoor use.
The EarlyGrow MPL50034/P/C is a 12 W, three-bay windowsill propagator at about £42.95, made in the United Kingdom, with a stated UK plug and 220–240 V. The heat is a fixed band of about 16–19°C, not a thermostat. It includes a vented lid and a capillary mat, and the capacity line says 1.4 litres. Two size lines disagree: 54.5 by 21.5 by 14.5 cm, and 51.5 by 21.5 by 13.5 cm. amazon.co.uk shows 4.5 from 304 reviews. That is the highest review count in this set at 4.4 or above, which is why it is the top pick. Reviewers grew salad, tomatoes and chillies on a kitchen sill. They also say headroom is tight and the mat can be too wet. It is not a greenhouse heater.
Pros
Cons
Best for: Salad, tomato and chilli seed on a kitchen windowsill, with a socket the lead can reach
Less suitable: A greenhouse, a large number of varieties, or anyone who wants a dial
Specifications
Common questions
Does the EarlyGrow propagator have a thermostat?
No. The heat is a fixed band of about 16–19°C. Reviews say it is not adjustable, and one buyer added an external thermostat.
Is a UK plug stated?
Yes. The item type states a UK plug, 220–240 V, and manufacture in the United Kingdom by Malton Plastics (UK) Ltd.
Will seedlings fit under the lid?
Reviews say headroom is limited, so labels have to lean and seedlings outgrow the lid. The bays are small if you want many varieties.
The WADEO MS-HG0430UK set is about £36.09: two mats and one digital thermostat claimed from 5°C to 45°C, with power-failure resume. The listing claims 50 W per mat and a rise of 5.6–11.1°C above ambient. Voltage is not printed, though the model code ends in UK. The title says 104 by 50 cm and the technical field says 52 by 25 by 1 cm, so the size is not settled. Waterproof has no IP code. amazon.co.uk shows 4.5 from 21 reviews. Twelve texts praise peppers and chillies, and they also say both mats share one setpoint and that soil temperature overshoots.
Pros
Cons
Best for: Two trays that can share one temperature, if you do not rely on a single printed size
Less suitable: Two different setpoints, or anyone who needs one agreed mat size
Specifications
Common questions
Can the two WADEO mats run at different temperatures?
No. The listing is one digital thermostat for two mats. Reviews say both mats share a setpoint.
Which size is correct?
The title says 104 by 50 cm. The technical field says 52 by 25 by 1 cm. The listing contradicts itself, so neither size is stated here as fact.
Do reviews mention overshoot?
Yes. Texts say soil temperature overshoots by several degrees even on the lowest setting, and that the mats get very hot.
The HBN combo is about £27.99: a 17.5 W mat and a digital thermostat claimed from 5°C to 42°C, with a probe, overload protection and error codes E1, E2 and E3. The controller bullet says it is rated up to 2,000 W. Voltage is not printed. Waterproof is wording only. The dimensions look like a package, and the mat area is not stated in centimetres. amazon.co.uk shows 4.4 from 48 reviews, with 17 stored texts. Buyers report faster chillies and tomatoes, and also a setpoint that did not stick, a reading that was way off, and a mat that did not cover two trays.
Pros
Cons
Best for: One seed tray when you want a dial and can accept a voltage that is not in the spec
Less suitable: Two full trays, or anyone who needs the voltage on the listing
Specifications
Common questions
What does the thermostat cover?
The listing claims 5–42°C, a probe, overload protection and error codes E1, E2 and E3. Reviews include a setting that did not stick and a reading that was way off.
Is the voltage printed?
No. The mat wattage is 17.5 W, and a bullet rates the controller up to 2,000 W. The supply voltage is not in the specification block.
Will it cover two trays?
The mat area is not stated in centimetres. One reviewer returned it because it did not cover two trays.
The Airmaster FW400 is a 520 W floor convector at about £25.94, with a printed thermostat of 5–30°C, a cut-out and a claimed cover of up to 10 m². The spec says indoor and IP20, while the blurb names greenhouses, animal housing and caravans. Two dimension lines disagree: 260 by 245 by 105 mm, and 35 by 17.5 by 35 cm. amazon.co.uk shows 4.3 from 173 reviews. Some buyers say it kept a 6 by 8 ft greenhouse or a cactus house from freezing on a low setting. Others say it is a small-room heater, and one says the thermostat failed in under two months. IP20 is not a wet-floor rating.
Pros
Cons
Best for: A small, dry, insulated space where a 5–30°C thermostat and about 520 W match the job
Less suitable: A wet greenhouse floor, a wall mount, or a large uninsulated house
Specifications
Common questions
What thermostat range is printed?
5–30°C. One caravan review says it came on around 6°C. There is no timer in the spec. A cut-out switch is listed.
Can it go on a wet greenhouse floor?
The spec says IP20 and indoor, and floor standing only. IP20 is not a splash or jet rating. The blurb still names greenhouses.
Which size line should you use?
The blurb says 260 by 245 by 105 mm. The item-dimensions field says 35 by 17.5 by 35 cm. Both are in the product data, so the size is not settled here.
The AC Infinity THERMOFORGE T7, model AC-SFT7, is about £119, with a claimed 1,000 W, ten heat levels, a probe, and VPD or temperature control. The listing prints 120 V AC. That is the wrong supply for a UK 230 V socket, and the listing does not show a BS 1363 plug. Ducting is not included. An IP code is not stated. amazon.co.uk shows 4.3 from 57 reviews. Almost all of the 36 stored texts are from the United States or Canada, and one is from the United Kingdom. Growers praise a 4 by 4 ft tent with a UIS controller. One meter reading over 1,600 W is among the stored texts. Do not treat this listing as a 230 V UK appliance.
Pros
Cons
Best for: A grower who already has a 120 V supply and a UIS controller, and who has checked the plug
Less suitable: A UK mains socket, a glasshouse frost tube, or anyone who wants UK review texts
Specifications
Common questions
Is the THERMOFORGE T7 a 230 V UK heater?
The listing prints 120 V AC. The product data does not show a BS 1363 plug. Do not treat it as a 230 V UK appliance.
Are the reviews from the United Kingdom?
amazon.co.uk shows 4.3 from 57. Of the 36 stored texts, almost all are from the United States or Canada, and one is from the United Kingdom.
What is in the box?
Detachable extended hosing, a sensor probe and the claimed smart controls. Ducting is not included. There are two ports.
The Morris 2 ft tube is about £29.99, 120 W at 240 V and 0.5 A, IP55, with a claimed cover of 4 m². The listing includes wall or floor brackets and a 90° thermal cut-out. Reviews say there is no dial. The same page lists 60 W to 240 W for 1 ft to 4 ft versions; this ASIN is the 120 W tube. amazon.co.uk shows 4.1 from 500 reviews. Buyers use it to take the chill off cupboards, boats and sheds, often with a separate thermostat. Several say 120 W does not warm a room, and some tubes died within months. A one-year defect warranty is stated.
Pros
Cons
Best for: Background warmth in a shed or cupboard when you add your own thermostat and want IP55
Less suitable: A room that needs a dial, or a 6 × 8 ft greenhouse on 120 W alone
Specifications
Common questions
Does the Morris tube have a thermostat you can set?
The spec lists a 90° thermal cut-out. Reviews say there is no dial, so it is not a 5–30°C greenhouse stat unless you add one.
What does IP55 mean on this listing?
IP55 is printed on this 120 W tube. The listing also names bathrooms and greenhouses. The heat is described as background, not a fan heater.
Is 120 W the only size on the page?
This ASIN is the 2 ft, 120 W tube. The listing also shows 60 W, 180 W and 240 W for 1 ft to 4 ft versions.
The LightHouse 09-435-250 is about £22.99 and sold as a greenhouse heater. The title says 45 W and the heat-output field says 50 W, at 230 V and 0.22 A. Reviews say there is no thermostat. The coverage field prints 8.611129 with no unit. The spec says outdoor and floor mount, and at least one review could not see a wall fix. amazon.co.uk shows 4.0 from 495 reviews. Buyers who were pleased used it in a cupboard, a cold frame or a potting shed. Several say 45 W does not lift a greenhouse. Failures in the texts include smoke, a fallen end cap and units that stopped heating.
Pros
Cons
Best for: A cupboard, cold frame or potting shed if you add your own thermal switch
Less suitable: A 6 × 8 ft greenhouse, or anyone who wants a dial on the heater
Specifications
Common questions
Does the LightHouse heater have a thermostat?
Not in the review record. Several buyers say it runs whenever it is plugged in, and some add a separate thermal switch.
Is it 45 W or 50 W?
The title says 45 W. The heat-output field says 50 W. Both figures are in the product data, so neither one is settled here.
Will 45 W heat a greenhouse?
Several reviews say it does not. One small box rose 2–3°C and one shed by about 1°C. Buyers who were pleased used a cupboard, a cold frame or a potting shed.
The Levson LDPHM-200 is a 20 W seedling mat at about £14.36. The listing prints 230 V, a claimed 20–30°C band that is not a setpoint, and IP65, and it says not to treat the mat as a room heater. amazon.co.uk shows 3.8 from 12 reviews. Seven stored texts are recorded. Reviewers who liked it used it under a seed tray. Others said seedlings cooked because there is no temperature setting. One United Kingdom review says the mat stayed cold after a single use. One Ireland review received an EU plug twice although the picture showed a three-pin plug. It is the lowest price in this set, and the star line is the weakest.
Pros
Cons
Best for: A small seed tray if you will watch an unregulated mat and can check the plug in the box
Less suitable: Anyone who needs a setpoint, or a greenhouse that must stay above freezing
Specifications
Common questions
Does the Levson mat have a thermostat?
No. The listing claims a 20–30°C band, and the reviews say it is on all the time. There is no setpoint.
Can you immerse this mat?
IP65 is printed. The page does not say you can immerse it, and a bullet says not to treat it as a room heater.
Did every buyer get a UK plug?
One Ireland review says an EU plug arrived twice although the picture showed a three-pin plug. The specification block does not name BS 1363.
Eleven plant heaters on amazon.co.uk were scored from the listing facts in this set. The displayed score is the star rating multiplied by 20. It is not a laboratory, germination or frost-protection score. A 4.7 therefore shows as 94 even when the review count is small or the listing contradicts itself. The top pick is the listing with the highest review count at 4.4 or above that also states a UK plug and 220–240 V. The best value is the lowest shelf price at 4.4 or above with at least 200 reviews. Price does not set the score. There was no lab test.
Review evidence
35%The amazon.co.uk star average, multiplied by 20, is the displayed score. A larger count at 4.4 or above outranks a higher star line on a small file. The RC SLL mat scores 94 from 46 reviews and is not the top pick.
Job and setpoint
25%A tray mat, a lidded propagator, a tube and a convector are different jobs. A thermostat counts when you cannot watch the tray, and when a greenhouse heater should run only on cold nights.
Voltage and plug
25%UK mains are 230 V. Credit depends on a printed 220–240 V supply and a stated BS 1363 plug. A listing that prints 120 V is the wrong supply for a UK socket.
IP code and conflicts
15%IP20, IPX4, IP55 and IP65 are recorded as printed. Waterproof with no code is weaker. A clash in wattage, size or pack count reduces confidence in that row.
Start with the job, then with whether you can set a temperature, then with the voltage and the plug. Wattage and the IP code decide whether the listing matches the space. The notes below follow that order for these eleven listings.
A plant heater on amazon.co.uk is one of four tools. An unregulated PVC mat, often about 25 by 50 cm and 17.5–20 W, sits under a seed tray. A thermostat mat adds a probe. Ranges printed in this set include 5–42°C, 5–45°C and 20–45°C. A lidded windowsill propagator is a different object. The EarlyGrow three-bay unit is 12 W, about 16–19°C, with a stated UK plug and 220–240 V, and no adjustable thermostat. An air heater is for when the greenhouse itself must stay above freezing.
Bottom heat under a tray does not hold greenhouse air above freezing. Expecting 45 W or 120 W to hold a 6 by 8 ft house is the same mistake at a larger wattage. Check the claim with a min/max thermometer.
IP20 is not splash-proof. IPX4 is splashes. IP55 and IP65 are jets. The word waterproof, with no code, is weaker. Do not immerse a mat, and do not wet a heater.
UK mains are 230 V, and a domestic appliance should have a BS 1363 plug. The THERMOFORGE T7 listing prints 120 V. One Levson review received an EU plug twice although the picture showed a three-pin plug.
Choose bottom heat, a lidded propagator or an air heater first. Do not cross them. Unregulated mats in this set claim a band such as 20–30°C or about 24–30°C and have no dial. Thermostat mats print 20–45°C, 5–42°C or 5–45°C. EarlyGrow is a fixed band of about 16–19°C. The Morris tube has a 90° cut-out and no dial in the reviews. The Airmaster prints 5–30°C. The THERMOFORGE prints ten levels and a probe, at 120 V. Mats here are about 12–50 W.
Prefer a printed 220–240 V supply and a stated BS 1363 plug. EarlyGrow states both, and UK manufacture. The HBN 17.5 W mat prints 230–240 V and does not name the plug. Several thermostat mats do not print a voltage. The THERMOFORGE listing prints 120 V AC. Regulation 35 of the Electrical Equipment (Safety) Regulations 2016 is the plug rule for appliances intended for UK domestic sockets. A 120 V product is the wrong supply for that socket.
Three typical situations, each with a recommendation from this comparison.
You want a lidded propagator, not a greenhouse tube. The EarlyGrow three-bay unit is about £42.95, 12 W, with a stated UK plug, 220–240 V and 4.5 from 304 reviews. The heat is a fixed band of about 16–19°C. Headroom is tight, and 12 W will not hold a greenhouse.
Pelargoniums, fuchsias or cacti need air heat, insulation and a thermometer, not a seed mat. The Airmaster FW400 is about £25.94, 520 W, with a printed 5–30°C thermostat and 4.3 from 173 reviews. The spec says indoor and IP20, so it is not a wet-floor rating.
You can switch the mat off yourself. The HBN 17.5 W mat is about £14.99, with 4.6 from 283 reviews and 230–240 V printed. There is no thermostat and no IP code. It will not frost-proof a greenhouse.
The top pick is HBN 17.5 W seedling mat, with the highest score in this comparison (9.2 out of 10, from 283 amazon.co.uk reviews). The best value for one seed tray is the HBN 17.5 W mat at about £14.99, with 4.6 from 283 reviews and no thermostat. The RC SLL mat scores higher on the star line, 4.7 from 46, and the title and a bullet disagree on the pack count. The AC Infinity THERMOFORGE T7 prints 120 V. Do not treat it as a 230 V UK appliance.
HBN 17.5 W seedling mat
About £14.99 with 4.6 from 283 reviews, the lowest shelf price at 4.4 or above with at least 200 reviews.
Editorial
Products Compared publishes British-English buying guides based on amazon.co.uk listings and public UK sources. We do not run a lab and we do not invent test scores.
Guides on what to look for, how to use a product, and common mistakes.
Public UK sources for greenhouse heat, sowing temperature and electrical safety, plus the amazon.co.uk listing facts in the display file. Shelf prices and star lines are those captured figures, not a live re-check.
This page contains affiliate links to amazon.co.uk. If you buy through them, we may earn a commission at no extra cost to you. Prices, stars and review counts are the captured UK listing figures in this set. We did not lab-test these plant heaters.
