Seedling heat mat with a thermostat

Updated: October 2026

You are looking at two products that both call themselves a seedling heat mat. One stays on until you pull the plug and lifts the compost above the room.

You are looking at two products that both call themselves a seedling heat mat. One stays on until you pull the plug and lifts the compost above the room. The other aims at a number you set, and only does that if the probe is in the compost. A third case in this set adds a clock. This page compares the 12 amazon.co.uk listings on our seedling heat mats table. The Products Compared editorial team used the listings and The English Garden. A purchase through our amazon.co.uk links can earn a commission at no extra cost to you.

Our top picks

Badge	Product	Control	Set range	Timer	Note	Price	Offer
Best overall	HBN HBN 17.5 W fixed heat mat	None; leave it on until you unplug it	About 24–30°C claimed, not a setpoint	Not stated	7.8	about £14.99	View offer
	WADEO WADEO 50 W probe heat mat	Digital thermostat with a separate probe	5–45°C	Not stated	8.0	about £24.22	View offer
Alternative	WADEO WADEO 30 W timer heat mat	Probe thermostat and a 0–12 hour timer	5–45°C	0–12 hours; 0 hours means continuous	6.6	about £26.64	View offer

Best overall

HBN HBN 17.5 W fixed heat mat

7.8/10about £14.99

View offer

Rank 2

WADEO WADEO 50 W probe heat mat

8.0/10about £24.22

View offer

Alternative

WADEO WADEO 30 W timer heat mat

6.6/10about £26.64

View offer

On this page

1.A lift is not a set point
2.The fixed pads in this set
3.The thermostat kits, and where they are thin
4.Gears and a clock timer

A lift is not a set point

A fixed mat adds heat on top of the room. The English Garden puts an unregulated 17.5 W mat at roughly 8°C above the surroundings, and switched it off by day in a warm house. Eight degrees is their example of that wattage, not a number you can type in. A room at 12°C plus that lift is still short of 21°C compost. A room already at 19°C can overshoot if the mat cannot switch off. Only a working thermostat is a setpoint, and the probe has to sit in the compost. Crop, footprint and plug come first, on the seedling heat mat buying guide.

The fixed pads in this set

Three listings are fixed. The HBN CP-C93 is £14.99, 17.5 W, 230–240 V and 25 × 50 cm, with 4.6 from 283 reviews. It claims about 24–30°C and gives you no dial. It is the best value, and it remains a lift. The Senua is the same £14.99, at 20 W and 25 × 52.7 cm, with 4.6 from 66 reviews, a claimed rise of about 10–20°C, and an IP67 sentence of 1 m for 30 minutes. Voltage is not printed. The RC SLL listing is £42.99, 4.7 from 46, at 18 W per mat as written, with no thermostat in the box, a four-pack title and one bullet that says one pad. You buy these three when you will be there to pull the plug.

Testsieger

HBN HBN 17.5 W fixed heat mat

7.8/10about £14.99

View offer

The thermostat kits, and where they are thin

The AOOWU JX02 at £18.99 and the JX03 at £24.99 both state 20–45°C and IPX4, omit wattage and voltage, and share seven texts, so they do not describe the square on their own. The WADEO HG0281EU at £24.22 is the clearest probe in the long files: 50 W, 52 × 25 cm, 5–45°C, 4.5 from 404. It is the top pick for that reason. The model code ends in EU and the plug is unnamed. The two-mat title at £36.09 says one thermostat for both mats, so one setpoint, not two. Who should take which job is on the best seedling heat mat page.

Gears and a clock timer

The Gsycle at £8.90 claims three gears and about 40–45°C, prints no watts or volts, and shows 3.2 from 12 reviews. A review measured at least 50°C on the lowest gear. Reviews call it USB-powered. The WADEO HG0380UK at £26.64 is the thermostat with a clock: a probe at 5–45°C, a 54 × 27 cm mat, and a timer of 0–12 hours. Zero hours means continuous heating. Setting 24 does not keep it on for a day. A meter note sat around 22 W against a stated 30 W. You buy it when you want the heat to stop after a set spell.

Common questions

Does a fixed mat hold 21°C?

It holds a lift above the room. The HBN claims a band of about 24–30°C and gives you no dial. The Senua claims a rise above the room. If the room is 12°C, you should not expect chilli compost at 21°C from either of them. If the room is already warm, the same mat can run hotter than the packet. A thermostat with the probe in the compost is the listing that can be aimed at 21°C, where its printed range includes 21°C.

Which listings have no thermostat?

The fixed HBN CP-C93, the Senua 20 W mat, and the RC SLL mats. The RC SLL bullet points you at a separate thermostat that is not in the box. The Gsycle has three gears and no probe, so it is not in the thermostat group either. Everything else in this set states a controller, with the gaps described above.

Which listings state a numeric set-point range?

AOOWU states 20–45°C. The WADEO probe mats state 5–45°C, and one review of the UK model saw 5–40°C on the unit in hand. The HBN combo states 5–42°C. The WADEO timer uses the same 5–45°C probe range and adds the clock. The HYDGOOHO does not print a dial range. It prints a claimed lift over the room.

What does the 0–12 hour timer add?

It adds an off-switch that a plain thermostat does not have. A thermostat cycles to hold a temperature and can still run all night. The timer on the 30 W WADEO ends a spell you set between 1 and 12 hours. Zero hours leaves it on. That is useful when you are out for the day. It does not replace the probe, and it does not fix a cold border.

Why can a thermostat still miss the set point?

The probe may be in the air, the mat may be hotter in the centre than at the edge, or the controller may be failing. WADEO reviews describe all three, including compost that overshot the set point by several degrees and displays that died. One HYDGOOHO review would not reach 25–27°C. A printed range is the claim. A compost thermometer on the first day is the check.

How to use a seedling heat mat