When and how to amend garden soil
Your garden soil is like your bank account: In the long run, you can’t afford to withdraw more than you deposit. Whenever you harvest fruits, vegetables, or flowers, you’re making withdrawals. Whenever you dig amendment into the soil or add mulch to the surface, you’re making deposits. Organic amendments ― compost and rotted manure, for example ― fatten up the soil bank. They rejuvenate poor soil, allow excess water to drain away while leaving enough moisture for roots, and retain nutrients until feeder roots need them.
Now, before spring planting, is a good time to enrich the soil for robust flowers and vegetables later this year. Keep in mind that beds for most trees, perennials, and native shrubs and groundcovers don’t need to be amended unless soil is sand or heavy clay. Just till and plant.
What to use and how to use it
A mix of composted grass clippings, leaves, and tree prunings is ideal for most flower and vegetable beds. Use your shovel or rent a rotary tiller to mix a 2- to 4-inch layer of organic amendment into the top 8 to 12 inches of soil.