What type/wattage bulb to use for large tort outside for winter?

[omgdoubletacos]

I would just like to know what kind of bulb and what wattage everyone uses for their big guys outside during winter. I have a 100 w heat (red) bulb right now, but I feel like it's not keeping him warm enough.

 

[wellington]

Get a pig blanket, a reptile radiant heat panel and a thermostat to run them. I use both in Chicago and Tom uses them for his Sullies in Cali. If you get really cold, add an oil filled portable radiator heater.