What size garden do I need?
Before using our garden calculator below, read these guidelines to get you started. The size of your garden is determined by a number of variables. Some of these are established by the conditions of your yard (such as soil type and yard slope), while others are determined by you (such as amount of roof top to be addressed or rainfall to prepare for). Enter information for the four items across the top (surface area, downspouts, soil type, and slope) then slide the rain gauge up and down to see how rainfall capacity influences the size and cost of your garden.
Most houses are square or rectangular so measuring the length and width of your house will give you the surface area that collects water. If you have an unusually shaped house or are just connecting a portion of an area, calculate the square footage and enter it directly here.
Most roofs are symmetrical so you can enter the number of downspouts attached to the surface area that you just measured. All values are per downspout — if connecting more than one downspout to the garden, multiply garden size by total number of connections.
Soil type determines how quickly water is absorbed into the ground. Most soil in Western PA has a high clay content, we can help you determine your soil type.
Yard slope determines how deep your garden is. Find the slope of your yard.
Remember — these are guidelines, not rules! Each garden site and individual circumstances are different. If your yard or budget can not accommodate the garden size recommended, consider limiting the amount of rooftop directed to the garden or installing multiple smaller gardens. No matter what size garden you put in, something is better than nothing!