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Best plant heater

Updated: October 2026

The best plant heater in this amazon.co.uk set is not the highest star line and not the cheapest mat. If you are sowing salad, tomatoes, or chillies on a kitchen windowsill, the EarlyGrow three-bay propagator is the top pick. If you want one bare tray and you will switch the heat off yourself, the HBN 17.5 W mat is the best value. The pick follows the review file and the UK plug. Prices and counts are on the [plant heater comparison](/hub/plant-accessories/plant-heater). The Products Compared editorial team compared those listings on 16 October 2026. We did not run a lab test. A qualifying purchase can earn us a commission at no extra cost to you.

The best plant heater in this amazon.co.uk set is not the highest star line and not the cheapest mat.

Our top picks

RC SLL RC SLL 18 W heat mat

Best overall

RC SLL RC SLL 18 W heat mat
9.4/10about £42.99
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HBN HBN 17.5 W seedling mat

Best value

HBN HBN 17.5 W seedling mat
9.2/10about £14.99
View offer
EarlyGrow EarlyGrow 3-bay heated propagator

Rank 3

EarlyGrow EarlyGrow 3-bay heated propagator
9.0/10about £42.95
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On this page
  1. 1.Top pick for a windowsill
  2. 2.Best value for one seed tray
  3. 3.High stars that do not win
  4. 4.Who should leave this set

Top pick for a windowsill

The EarlyGrow MPL50034/P/C is £42.95. It is a 12 W, three-bay windowsill propagator, 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 dial. 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, so measure the sill against the larger figure. amazon.co.uk shows 4.5 from 304 reviews, the highest count in this set at 4.4 or above. The Royal Horticultural Society says many seeds germinate around 18°C, and the packet comes first. Reviewers grew salad, tomatoes, and chillies. They also say headroom is tight and the capillary mat can be too wet. You cannot turn the heat down on a sunny sill. Twelve watts will not hold glasshouse air above freezing.

Best value for one seed tray

The HBN CP-C93 is £14.99, the lowest shelf price here at 4.4 or above with at least 200 reviews. It is 17.5 W, with 230–240 V printed and a claimed band of about 24–30°C that is not a dial. The listing describes it as about 10 by 20 inches (25 by 50 cm). amazon.co.uk shows 4.6 from 283 reviews. Buyers praise plug-in use under tomato and pepper trays. They also say there is no timer, heat can be uneven, and one mat stopped after one or two months. Waterproof has no IP code. That file is why it is the best value, and why the Levson at £14.36 is not. The Levson prints 20 W, 230 V, and IP65, and amazon.co.uk shows 3.8 from 12 reviews. Twelve reviews do not beat 283 at the same job. You switch the HBN mat off yourself.
RC SLL RC SLL 18 W heat mat

Testsieger

RC SLL RC SLL 18 W heat mat
9.4/10about £42.99
View offer

High stars that do not win

The RC SLL BHD-100 is £42.99 and shows 4.7 from 46 reviews. It is an 18 W mat with no thermostat in the box, voltage is not printed, and the pack count is not settled. The AOOWU is £18.99, claims 20–45°C, and shows 4.6 from 11 reviews, with wattage and voltage absent. The Morris tube is 4.1 from 500 and the LightHouse is 4.0 from 495, so both miss a 4.4 floor despite large files. The Airmaster, at 520 W with a 5–30°C thermostat, is the air heater in the set and is not the top pick, because the top pick is the seed job. No listing here is both 4.2 or above and at least 500 reviews. The filters behind that floor are on the plant heater buying guide.

Who should leave this set

Buy the EarlyGrow if the sill, the UK plug, and a fixed band near 18°C match the packet. Buy the HBN mat if one tray and a large review file matter more than a dial. Leave the set if the greenhouse must stay above freezing. That sits on the greenhouse frost heater page.

Common questions

What is the top pick in this set, and who is it for?
The top pick is the EarlyGrow three-bay propagator, £42.95, 12 W, about 16–19°C, with a stated UK plug and 220–240 V. amazon.co.uk shows 4.5 from 304 reviews, the largest file at 4.4 or above. It is for salad, tomato, and chilli seed on a kitchen windowsill. Skip it if you need a greenhouse, many varieties, or a thermostat.
What is the best value, and why is the cheaper Levson not that pick?
The best value is the HBN 17.5 W mat at £14.99, with 4.6 from 283 reviews and 230–240 V printed. The Levson is £14.36 and prints IP65, but it is 3.8 from 12, with cooked seedlings, a mat that went cold, and an EU plug that did not match the picture. The value rule is the lowest price at 4.4 or above with at least 200 reviews.
Why is a 4.7 not ahead of a 4.5?
The RC SLL mat is 4.7 from 46 reviews. The EarlyGrow is 4.5 from 304, with a stated UK plug and 220–240 V. Multiplying stars by 20 puts the RC SLL ahead on the score and it still loses on file size, missing voltage, and a pack count the listing does not settle.
Should a greenhouse owner buy the EarlyGrow?
Not if the job is keeping the air above freezing. The EarlyGrow is 12 W under a lidded windowsill unit. Reviewers used it for seed, and the listing is not a greenhouse heater. A greenhouse needs an air heater sized to the house, which this page does not award.
Is the £119 tent heater the premium pick for a UK socket?
No. The THERMOFORGE T7 prints 120 V AC. UK mains are 230 V, and this file does not show a BS 1363 plug. The price and a claimed 1,000 W do not correct the supply. Most review texts in the file are from the United States or Canada.
Do star ratings here come from a lab?
No. They are amazon.co.uk star ratings and review counts. We did not germinate seed or hold a greenhouse overnight. The displayed score is the star line times 20, and it can sit on a small sample or a 120 V listing.

Related pages

How to use a seedling heat mat

Seedling heat mat or greenhouse heater

Plant heaters

Plant heater buying guide: job, voltage, plug and IP

Greenhouse frost heater for pelargoniums and fuchsias

Sources

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.

  1. RHS: heating greenhouses efficiently (retrieved 16 October 2026)
  2. RHS: electricity in the garden (retrieved 16 October 2026)
  3. RHS: sow seeds indoors (retrieved 16 October 2026)
  4. RHS: April greenhouse jobs (retrieved 16 October 2026)
  5. Electrical Equipment (Safety) Regulations 2016, regulation 35 (retrieved 16 October 2026)
  6. NICEIC: gardens and electrics (retrieved 16 October 2026)
  7. Gardeners' World: heated propagators (retrieved 16 October 2026)
  8. Thompson & Morgan: heating a greenhouse (retrieved 16 October 2026)