It's the dirtiest little secret among gardeners: Soil provides the key to plant health and a garden's vitality. The type and quality of your soil affects not only the success of your garden, but how you'll spend much of your time working there.

Ideal soil offers a hospitable environment for plants in a blend of air, water, and nutrients. But the ideal loam, a humus-rich balance of silt, sand, and clay, eludes most gardeners. Even those who are fortunate enough to start with good soil must contribute to its improvement regularly because soil is a living layer of earth that changes naturally with time and the weather.

Follow these general guidelines in working your soil:

• For long-term success, it's better to feed the soil than the plant.
• Feed your soil every season and every time you plant, using organic matter, such as compost, rotted manure, and chopped leaves.
• Don't dig when soil is too wet or too dry -- it damages the soil. Work soil when a fistful of it crumbles easily.
• Don't walk on your beds. Stepping on soil compacts it, preventing air, water, and nutrients from reaching plants.
• Avoid overtilling. Excessive rototilling or digging destroy the soil's structure, leaving it powdery or rock hard.