Temp control for propagator. Help!

I keep my propagator in the utility room (65 degrees day, 55 degrees nights). At night I turn on a 7 1/2 watt bulb under the tray and the soil stays about 70 degrees. During the day (when the florescent light is on and 7 1/2 watt bulb off), the soil temp rises to close to 80 if I'm not really careful about opening the window wide open. Soon I will be moving seedlings to a lighted shelf in the same room, but I'm afraid that the temp will be too high from the lights. Any advice or suggestions? Propagator covered, seedlings on shelf will be uncovered.

There might be something wrong with the fluorescent fixture, if it is making the temps go up that high! They shouldn't put out much heat at all, maybe a degree, but not 10 degrees. Are there regular light bulbs (incandescent) close by that might be adding to the temperature?

I grow my seedlings under lights and cooler temps after germination are ideal. The ones you describe, 65F day and 55F night, sound perfect for most plants in the seedling stage.

Sorry, scratching my head to try to figure out why your daytime temps are that high.

A good topic here. I recently read where some people make propagating tables with light bulbs under the trays, usually several of them (about 7 watts each). By turning on or off some of the lights the heat could be adjusted. It also went on to say that the TOP of the fluorescent light is where the heat comes from (the ballast side) and not so much from the bulbs. Apparently some people put their flats right on the top.

Things that puzzles me tho is, I am wondering how to make one with lights below the flats for heat...because wouldn't the water from watering the flats drip down into the lights/electricity?

As for your heat, Fuchsia, are your trays enclosed in plastic? That would really hold in the heat. And also, if the sun come in the window during the day that would REALLY heat up your trays...Greenhouse like!

I just bought a couple of timers at Walmart that have the option to turn on and off several times each 24 hour period. As the pin is pushed in or out (I forget which) the timer will come on. So you can set the timer to come on each even hour and shut off each odd hour. Anyhow a lot of control for lighting and/or heat control. Once I had everything hooked up together and the heating mat was turning off at night with the lighting. So I put the mat on it's own timer and had better luck.

I guess my heat gain is from the ballast. I will look and see if there is some way to expose the ballast to the room and not down to the plants. North window and 3 feet away. Absolutely no light other than ambient from window. Florescent light is on a timer. 7 watt bulb only plugged in at night when florescent is off. Plasic dome for germination and then plants are moved to more open air so that heat gain is not a problem.
Horseshoe - The propagator is a wooden box (husband is genius!)about 8 inches deep. Bulb is under a strip of wood about 6 inches wide about 4 inches off the bottom so that the heat does not just spot heat right under the seed flats. The box is sized so that one of the dome covered plastic trays with 9 cell inserts (removed) fits right in and rests on the top edge of the box. Then the little seed flats (Cottage cheese containers or whatever with drain holes) sit in the plastic tray so no water drips down.

'Shoe, I have seen kits for sale as Fuschiafan described. They are typical flat-size, and run about $40.00 each (light bulb not included). You got a great DH, there, Fuschiafan. I wish I knew a good carpenter :)

I suspend my lights from chains; that dissipates the heat into the room. Maybe I can figure out a way to convert some of that heat, so I can use it for a propagator??? Something to work on for next fall/winter. I can always use more plant space, especially if there is a way to heat it above room temp.

Thanks lupine...if I could see a pic of one of them I'm sure I could build one. I really need one for 4 or 5 flats so could just build a long one with rows of bulbs. Peppers really germ SLOW unless the heat is way up!

By the way, if you have multiple shelves with fl. lights, the heat from the ballast end (top) of the lights could heat the flats on the shelf above each light. Once they're germed then something can go to the bottom shelf to utilize the light but be at a cooler temp down there.