Heat mat recomendations

Recently purchased a garland 7 tray window propogator recent temperatures have killed off all the seeds. As propogator doesn't have a thermostat and only heats up to 13 degrees can anyone recommend one that's suitable for tropical seeds. Than you in advance I have limited space window seal in unheated room

 

I use one very similar to this one. It keeps my propagator around 24c even in my unheated greenhouse - but I don't use it until March.

Garden Greenhouse Plant Seedling Heat Mat Thermostat With Temperature Control | eBay UK

PS - I put the heat mat on the bottom of my propagator (my propagator sits on some insulating foam) and about 1" of sand on top of the mat - the sand keeps the heat stable and acts sort of like a storage heater.

 

Thank you for recommendation have purchased this will give it a go.

 

There are relatively inexpensive plug in thermostats , such as the Inkbird 308* which could regulate electric heating.
Beware direct solar heating in greenhouses , windows etc Even this week my unheated greenhouse closed up (max 4 deg C outside) reached 27.4 deg C in an extended sunny 5 hours.
*
Inkbird Digital Prewired Thermostat Temperature Control ITC-308 Heat Cool UK Fan | eBay UK

 

I'm just wondering if you might be a bit early, germination is the easy bit at this time of year, growing on afterwards is often the problem if you are restricted for heated space.

 

For any such heated propagator you are better placing it on a thick layer (eg 25mm) of polystyrene to act as an insulator from the cold below.

Also making a secondary larger cover to help keep as much heat in as possible.
Use some cheap bubble wrap to make an effective cover and if possible remove the unit away from the window during this cold weather.

That said you then have to be doubly careful on a window cill as on a sunny day even in winter the propagator can get way too hot and the seedlings wilt.

As said, its very early for seed sowing without some heating and lighting not just for the germination but to keep the seedling and young plants growing in these winter months, with Tropical (?) plants even more difficult.

 

This is one of my 2 heated propagators I cobbled together -