need info,
 

i have a lean-to greenhouse on the side of an unheated garage. i'm looking for the most economical heating for it, i live in zone 5, mid michigan.also looking for the best economical grow lights, i have 1 lemon tree, 2 avocados, 3 small dwarf cavendish bananas,rooting orange tree and 1 pineapple. any and all help would be appreciated, thanks baker mike- i'm also a fairly new member.

Re: need info,
 

Hello bakermike! Welcome to bananas.org! I too live in an area that requires plants to be overwintered indoors. The benefit of lean-to greenhouses is that they are less exposed to the elements than a free standing structure. This should help stabilize the interior temperature and reduce heating costs. The type of heater needed will depend on several factors: 1)size of the greenhouse 2) type of material the greenhouse is constructed from 3) desired minimal temperature, especially at night & 4) amount of passive solar heating during the day. For small greenhouses that are fairly well insulated and sheltered, a small electric space heater can do the trick, although for most greenhouses, it must run throughout the night just to keep temps above freezing. Caution must also be exercised because many common models are not weather/waterproof. If you would like to keep the greenhouse at a higher temperature, a dedicated unit such as an electric or gas greenhouse heater will be well worth the investment. The best place to start for heaters is a greenhouse heating calculator that should give you a good idea of the BTU's needed after factoring for a wide set of variables.

Greenhouse BTU Calculator - International Greenhouse Company

ACF Greenhouse Heaters & Heater Size + Cost to Heat Calculators

Supplemental lighting is super helpful in winter months for tropical plants. Just like with heating, the desired state of the plant is an important consideration. It is possible to put many tropical plants into a low growth stage during the winter months that makes them easier to keep alive until next summer, in which case, light and temperature requirements are much lower. If you wish to keep them actively growing, however, light levels will need to be much higher. For the best effect, High Intensity Discharge (HID) or Sodium Vapor/Metal Halide lamps are recommended as the best choice for greenhouses. However, these units can quickly become expensive and require a notable amount of energy. A more economical choice would be T5 fluorescent grow lamps, which work fairly well, but generally lack the intensity of HID or Sodium Vapor/Metal Halide kits. T5 systems would definitely be my recommendation for the best value and "bang for your buck."

Amazon.com: Hydrofarm JSV4 4-Foot Jump Start T5 Grow Light System: Patio, Lawn & Garden

I have used T5 set ups in the past to grow small plants and start seedlings, and have always found them to work well. I must say that I do not currently have a greenhouse, but as a tropical plant enthusiast, I have spent many hours researching greenhouses and effective winter set ups to overwinter plants. I hope this helps!