like karin_mt, I use several heating mats for seedlings in my greenhouse. They measure 48" X 18" and provide about 100 watts each (about the same as a light bulb). If you use a mat in a cold frame on the brick patio it should work well...as long as you get yourself a 1" thick piece of foam insulation. Make sure the foam piece is larger than the base of the cold frame, as that will help minimize drafts out of the bottom. I also bought myself a thermostat that the mats plug into. For about $35 you can get a thermostat with a probe on a wire that goes into the soil and helps maintain a uniform temperature. Otherwise, you may have temperatures that will not lead to good germination, or possibly cook your seedlings.

You did it! This looks like an excellent shelter for the birds, from the cold, wind and snow soon to arrive. This is also a great example of adapting something for more than one use (and both benefit the ecosystem). Keep us posted on what happens -

Thank you both for giving such great suggestions. I stumbled upon winter sowing on pinterest and even though it seemed logical, I was a bit skeptical. I am so thankful that I researched further and found this wonderful forum. You all have made me a believer for sure! I had a little time off work and I have to admit I have probably spent several hours at this point rifling through numerous posts on this forum. I cannot believe how much I have learned from you all. (huge thanks!).....now I have to attempt to put it into practice lol. jensyen-I will for sure be on the lookout for additional containers to continue using your method. So far, I have only rummaged up twelve that are also sown. As suggested, I am making notes and trying to keep them as organized as possible. morz8-You are absolutely correct. He is quite proud of his work:) Now i just have to figure out how to break it to him that I will be slicing holes in the top if I can't keep up with propping it open when the weather warms up a bit;) Again-huge thanks for the responses, the inspiration, and ALL the info. What a great find!

A cold frame means you are going to be checking on things and opening and closing it at least twice a day. You can't just plant in it and leave it. It has to be opened on a daily basis so your plants don't fry and closed up at night to retain some of the heat when the sun goes down. Even on a cloudy day it Must be opened a bit because it only takes a bit of sun to heat up that small place I presume you are going to plant in the ground not use pots. If that's the case don't use a soilless mixture. They are meant for pots not soil. What you want is good soil like you'd find in a well tended flower bed. First make sure there is nothing growing in your raised bed. Pull out any weeds and grass making sure you get all the roots. Loosen the soil by digging and top dress it with compost and rake it in. Now you are ready for planting. Make sure when you make the cold frame it either has a slant or an arch to run excess rain water at night or if you want to keep it off the bed. Also include some way to open just part of it when you don't want it open all the way. Such as a cold but sunny day. Put the top on and leave it closed for a week or 2 before you plant to warm the soil. This will also kill any weed seeds that are there. Note--A cold frame heats up fast in the sun. It only takes about 20 minutes with the sun shining on it to reach a too hot for plants stage. When I used cold frames before my greenhouse was built I'd open then early in the morning and close them around 4 Pm to retain the heat for the night