Check your soil to determine if it needs improvement. The best soil is well-drained and moist. Test it by wetting it thoroughly with your garden hose. Wait for 24 hours and then squeeze a handful in your hand. If the soil forms a ball that maintains its shape, but breaks easily when poked, your soil is ideal as it is and does not need improvement. If the ball of soil collapses rather than maintaining its shape, it likely contains too much sand. If the ball of soil maintains its shape even after poking it, refusing to break up, then the soil likely contains too much clay. Whether your soil has too much sand or too much clay, adding organic matter such as peat moss or compost will improve it.
pH is a measure of acidity or alkalinity. A pH measurement of 7 is neutral. Measurements lower than 7 indicate that your soil is acidic, with zero being the most acidic, while measurements higher than 7 indicate your soil is alkaline, with 14 being the most alkaline. Each plant species has an ideal pH range for optimal growth. Generally, a neutral pH of 7 is ideal as this is the range at which bacteria are able to decompose organic matter in the soil, releasing nutrients that are then available for your plants, and the ideal range in which microorganisms are able to convert free nitrogen in the atmosphere into a mineral form available to plants. If your soil is acidic, add lime, which is readily available at your local garden store. Bear in mind that hostas like acidic soil. If your soil is alkaline, add compost or manure. You can get a pH testing kit at your local garden store. Make this part of your annual gardening preparations as pH levels can change over time.
Organic matter promotes the growth and health of beneficial microorganisms. It also improves the structure of the soil, improving water and air filtration, and can reduce mineral deficiencies in soil.
How you add organic matter to the soil depends on what type of material you use. You can dig or till loose material such as compost, straw, grass clippings, chopped leaves, peat moss, or aged manure into the soil. This is best for bare beds before planting. Or you can apply an organic mulch to the surface that will decompose slowly over time, which is best for existing plantings.
How Much Organic Matter
A safe rule of thumb is to add 5% organic matter to your soil. A one-inch layer of fine-textured organic matter, such as compost, spread over the soil’s surface, equates to roughly 5% of the first foot of soil by volume. Apply a correspondingly thicker layer, such as 4 inches, for bulkier organic matter.
In our next post, we will discuss methods of improving difficult soils.
All-New Encyclopedia of Organic Gardening: The Indispensable Resource for Every Gardner, Fern Marshall Bradley and Barbara W Ellis, Editors