Heating a very small greenhouse in the garage

I have a small 36h x 24l x 19w (inches) that I want to put in the unheated garage to start a few seeds. I have the lights setup, but not sure the best (and cheapest) way to provide heat.

Its obviously not a large area to heat and I only need to warm the inside about 10-15 more degrees. I'm thinking a heat lamp bulb in one of those plug in plant lamps would do the trick. I'm extremely hesitant about an electric heater in such a small space, any ideas?

Thanks!

FeedMe, somewhere here on Daves a person used christmas lights, the small twinkle kind, to heat their small size GH.

the most common & efficient is a small heating mat similar to the heaters on water beds
goes under the seed tray
they aren't cheap but you can get them at nursery supply stores & of course on $bay
but one or two very small light bulbs the size used in nite lights will supply a surprising amount of heat
very similar to the bulbs in the older Xmas tree strings

I am using rope lights from Lowe's attached to the undersides of my wire matal shelves- they put out a gentle hest.

I second the idea from Jo. I have some of the rope-type Christmas lights that do a good job of provide a little extra heat. I'm currently using some on my outside faucets during the record cold temperatures we're having in Texas. The lights, coiled around the faucets, covered with a small box, have kept all my faucets clear in single-digit temperatures. The boxes are just warm to the touch. I haven't measured the temperature increase of the string, but bet that it is enough for your greenhouse shelf.

David

Thanks y'all, I have some christmas lights in the garage, ill light them up and see what the temperature reads tonight. I might not need them as its decided to already start warming up here!

FeedMe, I would not use regular Christmas lights- the bulbs could cause hot spots. Rope lights are encased in plastic and barely warm to the touch. Here's one photo of mine- I have since added a second set and they are doing very well.

I use strands of C60 Christmas lights with clear bulbs. I have been using them for 3 years now with no issues.