Two soil properties strongly affect its drainage: texture and structure. Texture refers to the size of soil particles. The larger they are, the easier water drains. Sand is the largest particle, clay the finest. Clay can water-log roots but holds nutrients well. Sand doesn't drown roots, but water carries nutrients away. Soil structure describes how soil particles come together. Platy soil, for instance, is arranged in layers or plates that make water travel sideways before going down. To find out how well your soil drains, you can perform a soil percolation test, or perc (also perk) test for short.
Dig a hole about a half-foot wide and about a foot deep.
Plant the yardstick in the hole so that one of the inch demarcations is level with the top of your hole. Make sure the stick is anchored well.
Fill the hole with water and let it completely drain out.
Fill the hole again, taking note of the water level on your yardstick. Note also the time.
Take note of how far the water has dropped every hour.
Evaluate initial results: If the water is draining an inch or two an hour, your soil is draining well. Above 4 inches of drainage an hour is too fast. Below an inch per hour is too slow.
Take note of how long it takes for the hole to completely drain. If the water isn't gone after about 12 hours, water won't drain well in your garden.