SUNPACK Digital Temperature Controller for Heat Mats

Dial-In Heat Mat Precision for Reliable Seed Germination

A heat mat running a few degrees too hot or too cold can be the difference between a tray of vigorous seedlings and one that never sprouts, but most heat mats plug straight into an outlet with no way to dial in an exact temperature. The Sunpack Digital Temperature Controller sits between the mat and the wall, holding root-zone temperature within the 68-108 degree F range most seedlings and cuttings need to germinate and root reliably.

A probe on a 6ft cord reads the actual growing-medium temperature rather than estimating from nearby air, and the display switches between Fahrenheit and Celsius depending on which a grower prefers. LED indicator lights show at a glance whether the mat is actively heating or holding steady at the set point.

Key Features & Benefits

• 68-108 degree F control range — covers the temperature window most seed germination and cutting propagation calls for.
• 6ft probe cord — reads actual growing-medium temperature at the root zone rather than ambient air temperature.
• Switchable F/C display — shows readings in whichever unit a grower is used to working in.
• LED status indicator lights — show at a glance whether the mat is actively heating or holding steady.
• Compatible with most 120V heat mats — works as a drop-in add-on between an existing mat and the wall outlet.

Who Should Use This

Growers starting seeds or rooting cuttings on a 120V heat mat who want consistent root-zone temperature rather than whatever the mat delivers unregulated are the right fit for this controller, especially in cool basements or garages where ambient temperature swings widely.

About Sunpack

Sunpack sells this temperature controller alongside its grow light and tray lines, rounding out the propagation hardware growers need to keep both light and root-zone temperature in the right range.

Frequently Asked Questions

How do I set up the controller with my heat mat?

Plug the heat mat into the controller and the controller into the wall outlet, then place the probe in the growing medium near the root zone rather than resting it on the tray surface. Set the target temperature on the display and the controller cycles the mat on and off to hold that point.

Will this work with any heat mat, or only Sunpack mats?

It is built to work with most standard 120V heat mats regardless of brand, since it controls power to the mat rather than communicating with mat-specific electronics. Confirm your mat's voltage and wattage fall within the controller's rated capacity before connecting it.

Where should I place the temperature probe?

Insert the probe into the growing medium a short distance from the heat mat's surface, in the same tray or flat being warmed, rather than leaving it in open air. This gives a reading that reflects the actual root-zone temperature seedlings are experiencing.

What temperature should I set for germination versus rooting cuttings?

Most seed germination happens fastest in the mid-70s to mid-80s F range, while many cuttings root well slightly warmer or cooler depending on species, so check the specific crop's preferred range. The controller's 68-108 degree F span covers both use cases without needing a second unit.