To test how well your garden soil drains, run the hose on the surface at different points around your garden. Then observe what the water does. If it drains away immediately, your soil is too sandy for most plants; dig in some compost, or other organic matter, or apply a mulch when the soil is wet to help it retain water.
If the water stands for 30 minutes to 1 hour, the drainage is ideal for vegetables and flowers. If it remains in the hole for several hours, your soil drains poorly. Either dig in some sand, manure or compost, or construct raised beds of improved soil.