Mars Hydro Seedling Heat Mat with Thermostat, 25 × 53cm

The Mars Hydro 10 × 20.75 inch heat mat is a seedling heat mat with thermostat: a 25.4 × 52.7 cm, 20W carbon-fibre mat with a digital thermostat and probe, so you can set the exact soil temperature for a standard seed tray or propagator.

A single seed tray of chillies on the windowsill, a probe tucked into the compost and a small display glowing a steady 26°C. This compact mat does the worrying for you, so you can simply watch for the first shoots.

A seedling heat mat with thermostat for steady, reliable germination

Seeds are fussy about warmth, and too much is as unhelpful as too little. The probe sits in the compost and the thermostat switches the mat off the moment your chosen temperature is reached, so trays stay comfortably warm without drying out or cooking.

If there’s a power cut, or someone unplugs it to charge a tablet, the thermostat remembers your last setting and carries on. It’s one less thing to think about on a busy morning.

What your heat mat and thermostat help with

• Germinating chillies, peppers, tomatoes and basil
• Warming one standard seed tray or a small propagator
• Rooting herb and houseplant cuttings
• Early spring sowings on cool windowsills
• Keeping trays at an exact, steady temperature

Exactly warm, never too hot

• Digital thermostat included. Set anywhere from 5 to 42°C; the display reads 0 to 60°C.
• Probe-controlled. A metal probe reads the compost temperature and the mat switches off at your target.
• Up to 27°C above room temperature. Plenty of warmth for even the slowest chilli seeds.
• Waterproof and wipe-clean. IP67-rated outer layers shrug off spills and drips.
• Remembers your settings. Memory function after a power cut.
• Folds away. Flexible and easy to store when sowing season ends.

Heat mats with thermostats: your questions answered

Why use a heat mat with a thermostat?
A thermostat keeps compost at a set temperature, so seeds get steady warmth without overheating or drying out.

What temperature should I set for seeds?
Around 20 to 25°C suits many vegetable and herb seeds, with chillies and peppers at the warmer end. Check the seed packet.

Where do I put the probe?
Push it into the compost of one of the cells or pots on the mat, so it reads the root zone temperature.

Is it waterproof?
Yes. The mat is IP67 rated, so you can wipe it clean after spills.

The details

In the box

1 × Mars Hydro seedling heat mat and 1 × digital thermostat with temperature probe.

Steady warmth from below, and a tray of seedlings that arrive right on time.