The Ideal Soil
So just what is the ideal soil? For most of the plants we sell at Great Garden Plants, you want a well-drained, loamy, nutrient rich soil with 5 percent organic matter and a pH between 6.0 and 7.2.
Now that we know what the ideal soil is, how do you get it? Soil preparation is the answer. Keep in mind that perennials, trees, shrubs and vines are permanent residents in your landscape, so preparing the planting area is the best investment you can make to get your plants off to a good start.
For best results, plants must have good drainage, adequate nutrients and available water at all times. If you are creating a new garden bed, begin by removing grass and weeds. Start by "peeling away" about two inches of the surface, and "skimming" the grass off with a spade.
Spread 2-3 inches of organic matter such as peat moss, compost, or aged manure (up to 4 inches if the soil is very poor), over the planting area, and thoroughly dig in, or till to a minimum depth of 6-8 inches. This will improve drainage in heavy clay soil, and will help sandy soil hold moisture longer. Break up clods of dirt, and remove rocks. Rake the soil level, and remove any large clumps.
Because the pH range of approximately 6 to 7 promotes the most ready availability of plant nutrients, and can also influence plant growth by its effect on activity of beneficial microorganisms, knowing your soil pH is important. The most accurate method of determining soil pH is having samples tested by a lab. A second option, which is simple and easy, consists of using a PH meter, or using certain indicators, or dyes. Meters and soil dye test kits can be found in many stores that offer gardening supplies. Be sure to test the soil in different areas of your garden, and at different depths (top 3 inches, 6 inches, and 12 inches) as plant deterioration, manure, and microbial activity can affect PH levels.
If your soil test indicates your pH is too high or too low, add lime or sulphur to correct it. A pH below 6.0 means your soil is acidic, and may need to be adjusted with dolomitic limestone. If the pH is above 7.2, your soil is alkaline, and can be adjusted with iron sulfate. Refer to your soil test for recommendations on additional plant nutrients.
In established gardens, remember to add organic matter every time you add a new plant. It's also a good policy to add a 2 or 3 inch layer of organic matter on top of the soil in the fall. As the organic matter breaks down, it will improve soil structure, help maintain a PH balance, and feed plants.