A 100 watt bulb will keep a small well-insulated room, like a well-house from reaching freezing temps, if you don't open the door but probably not a shed like you're talking about. Better go with the above suggestions to heat either the whole shed with an elec heater or build a box within the shed and use the bulb in that. Put in a thermometer and see if you're getting the desired temps before you put in the plants.

FWIW, every couple of years the gray vinyl siding on the north side of my house develops a greenish tinge. Cup of bleach in two gallon sprayer and it goes away. Gorgeous garden and estate, BTW. Ev

I built a 8x12 shed in MA and I put in on 4x4x16 and 2x4x16 blocks. If your not putting in anything heavy, no need for a concrete floor. Use pressure treated 3/4 inch tongue and groove plywood over 2x6 for the floor on top of 4x4x16 concrete blocks. Put the blocks on 3/4 crushed gravel. I removed the grass and dug down about 6 inches. I filled the holes with 3/4 gravel, leveled the blocks and made sure they were all the same height and in line with each other. If you are a little off, you can use regular asphalt shingles as shims. If you use multiple blocks and shims, make sure you put a layer construction adhesive between each block/shim. I spread the rest of the gravel under the shed to aide drainage.

I used vinyl and run up wall 6" are more work very well easy cleaned did gassing out side gas will pour back into container out side oil dry works on vinyl. A 2x4 table 4x4 legs pressure treated high, 8 foot long 3ft. wide works good outside gaps between boards makes easy clean off. I don't like plywood floor to hard clean. I buy my vinyl 2 foot longer and 2 foot wider so go up wall this makes corners easy to clean and around wall edges even if pole barn style wall 2x4 studs. This post was edited by gator_rider2 on Sun, Jun 23, 13 at 5:30