There’s more to planting shrubs than digging the right-size hole. To give your new woody ornamentals the good start they deserve in your garden, chances are you’re going to need to give the soil some rich organic matter so the root systems have a happy home. Amendments enrich the soil and improve its tilth (its physical structure). You can use any type of organic matter, from compost or composted animal manures to decomposed bark or leaf mold.
Garden tillers are helpful for mixing soil amendments and fertilizers, but for deeper mixing, double-dig the bed with a shovel.
Photo Credit: ©2002 Dolezal Publishing/John M. Rickard
Amendments improve soil texture or change the acid-alkaline balance of soil, while fertilizers add nutrients to it. Compost is both a light fertilizer and a texture enhancer. Garden lime and sulfur are used to alter soil pH. A soil test will help determine what kind of amendments your planting bed requires for best growing results.
Photo Credit: ©2002 Dolezal Publishing/John M. Rickard
Of course, what you add depends on your soil type. Both clay and sandy soils can be improved by tilling in compost or well-rotted manures. In clay soils, these amendments improve drainage and aeration. In sandy soils, they increase moisture-holding capabilities. In both cases, the amendments increase the activity of beneficial microorganisms and improve a soil’s ability to hold and release nutrients.
Some amendments also adjust soil pH levels. You can add dolomitic limestone to highly acidic soil, for example, to raise its pH, or work sulfur into highly alkaline soils to lower the pH. In both cases, base the amount of limestone or sulfur you add on the recommendations provided by soil test results.
A side benefit of organic amendments is that they provide trace amounts of micronutrients and trace elements to the soil. But if your soil needs more, you may need to incorporate fertilizer, too. The three key nutrients for plants are nitrogen, phosphorus and potassium (or N-P-K). Plants need nitrogen for foliage growth, phosphorus for root growth and flower development, and potassium to make them more winter-hardy and drought-tolerant. Most soils contain these nutrients in sufficient amounts, but if a soil test indicates that your soil is deficient in one or more of them, you should add the appropriate type of fertilizer to your shrub bed before planting.
A fertilizer’s analysis is shown on its label, displayed as three numbers, called the N-P-K ratio, which refers to the percentage of nitrogen (N), phosphorus (P) and potassium (K) by weight in the product. The numbers often appear in combinations such as 10-10-10, 0-5-5 or 15-1-1. Again, choose the best fertilizer based on your soil test results. If you’re uncertain as to what type to get, select a slow-release, low-potency, balanced fertilizer, and use it sparingly in your planting beds, mixing it deeply and thoroughly into the soil.
Once you’ve done your soil test and have determined what kind of amendments and fertilizers you need, gather your rake, shovel or spading fork, a tarp, tiller, wheelbarrow or garden cart, amendments and fertilizer. Then take the simple steps shown in the following pictures and described in their captions to properly prepare your soil before planting your shrubs.
Shrub Soil Preparation
Shrub Soil Preparation - Step 1
Begin by clearing your planting bed of all weeds and other unwanted plants. Remove any rocks and debris found at least 18 inches deep.
Photo Credit: ©2002 Dolezal Publishing/John M. Rickard
Shrub Soil Preparation - Step 2
Dig a trench 9-12 inches deep and one shovel-width wide along an edge of the bed, placing the removed soil on a tarp. Loosen the next 9-12 inches of soil within the trench with a spading fork or shovel.
Photo Credit: ©2002 Dolezal Publishing/John M. Rickard
Shrub Soil Preparation - Step 3
Widen the trench by another shovel-width, placing the top 9-12 inches of its soil into the first trench you’ve just dug. Progress across the area until all the soil in your planting bed has been dug. Fill the last trench with soil from the first. Use a tiller to mix the topsoil thoroughly.
Photo Credit: ©2002 Dolezal Publishing/John M. Rickard
Shrub Soil Preparation - Step 4
Cover the area with a 4-inch layer of organic soil amendment, as needed. Add synthetic or organic fertilizer, as needed, carefully following all package instructions.
Photo Credit: ©2002 Dolezal Publishing/John M. Rickard
Shrub Soil Preparation - Step 5
Using a shovel or spading fork, turn your soil amendments into the top 9-12 inches of soil.
Photo Credit: ©2002 Dolezal Publishing/John M. Rickard
Shrub Soil Preparation - Step 6
Rake the top of the bed smooth. It will be high and fluffy with air and amendments. Avoid compacting it to retain its texture. Water the area with a sprinkler, and allow it to settle for at least 24 hours before planting.
Photo Credit: ©2002 Dolezal Publishing/John M. Rickard
