• Greenhouse kits enable almost any homeowner to enjoy green plants year-round.Jupiterimages/Photos.com/Getty Images
  
  Homeowners should first determine why they want a greenhouse kit before shopping for one. Greenhouses can provide year-round protection for plants or just extend the beginning and ending of the growing season by a few weeks. Sturdier greenhouse kits can withstand cold winters and heavy snows, while others are designed for staving off light frost and medium winds. Kits can range in price from a few hundred dollars to over $30,000, with the more expensive kits providing many more options and much more space.
  
  

Sunshine

• A redwood frame, easy assembly, and an assembly video sets the Sunshine greenhouse kits off from the others. It comes in small, medium and large sizes, and the anti-drip polycarbonate panels minimizes moisture build up in the interior. The panels come preinstalled into the frames.
  
  

Early Bloomer

• The Early Bloomer kit has a strong, composite frame with Solexx twin-wall polyethylene 3.5-mm covering providing insulation for wintered over plants. The greenhouse can be picked up and moved to another location even after assembly.
  
  

Early Start

• The Early Start greenhouse kit is a good beginner's kit. It is inexpensive but comes with a sturdy aluminum frame. The Early Start is not designed to provide winter protection in cold climes. It comes with a polyethylene plastic covering that is adequate to keep out early and late season frost.
  
  

Cross Country

• Cross Country greenhouse kits are the upper high end of kits. They can become a four-seasons room addition to a home, with protection from the coldest weather, and come with a lifetime guarantee. The aluminum frame, storm door and tempered glass greenhouses are available in hundreds of sizes.
  
  

Juliana Greenhouses

• A well-known midrange greenhouse, Juliana Greenhouses have an aluminum frame and an insulated covering. The company offers several price ranges -- from a basic budget model to a heavy-duty premium greenhouse.
  
  

Easygrow Greenhouse

• The Easygrow Greenhouse features an exceptionally strong frame and insulated coverings. A wire system adds even more stability. The "push and click" assembly is quick and easy.
  
  

Gardeners Greenhouse

• The polycarbonate panels of the Gardeners Greenhouse snap into place and look more like glass than the standard greenhouse covering. The panels do not retain heat well, which limits the greenhouse to milder climates. The frame is lightweight and does not stand up to strong winds and heavy snow.