Loam is hands-down the best all-around soil for gardening. Any type of plant can be grown in loam without making major modifications or additions to the soil. It holds its shape when squeezed or compressed and crumbles slightly under pressure, which means that loam isn't overly dense or loose. Most loam is made from fairly equal parts of silt, sand and clay, giving it all the best qualities of each of these materials with few of the drawbacks. The sand content keeps the loam open so air, moisture and sunlight can reach the plants, while the clay and silt content slows down drainage and evaporation, keeping water and nutrients in place. Loam warms up early in the spring, won't dry out in the summer and still drains well in heavy rain, making it the perfect soil for year-round planting [source: BBC].
While loamy soils can vary in their specific makeup, they're usually easy to bring into balance by using simple additives. Compost or mulch can make up for minor imperfections in the soil content, creating a versatile planting base for virtually any type of plant [source: Gardening Data].