If you don’t have space for a walk-in greenhouse, this mini greenhouse is the perfect alternative. It is made from cedar boards and a repurposed window to save time and effort in construction. The hinged lid is perfect for providing ventilation and acclimating your seedlings before planting in the garden. You can make this greenhouse in a couple of hours using basic power tools. And check out our guide to how to start seeds indoors. This would also be the perfect size for a deck greenhouse.