Build a useful greenhouse easily and grow seedlings and even tropical plants throughout the year. The no-frost environment provided by a greenhouse allows you to enjoy gardening in very cold climates almost anywhere in the world. With so many greenhouse designs, you can be sure that there are a plethora of good greenhouse designs out there for your consideration. Choose the design that can help you to build an outdoor effective greenhouse. The secret to building an effective greenhouse is in taking the time during the planning stage to carefully assess your needs. While an effective greenhouse must obviously provide an appropriate environment for growing plants, this can be accomplished in many ways depending on your needs and preferences.