How to Prepare Soil for Planting

What season you are in dictates what you should be planting. However, many plants, especially potted plants, can be planted at any time of the year. Check the plant tag or consult with horticultural staff at your hardware or garden center for local knowledge. 

Before planting, check the condition of the soil. If the soil lacks nutrients, worm and microbial activity, or is dry, compacted, or waterlogged, then the plant may not thrive. Planting in healthy, fertile soil should ensure strong and healthy growth.

Firstly, what is soil?

Your soil is not just a sticky goop that happens to be outside; it is a living, breathing entity that needs to be cared for like any other form of life. Your soil is composed of half rock and minerals that have broken down into tiny particles over thousands of years, and half microbes and bacteria that break down organic materials like leaves, roots, and compost. These organisms feed on the compost and create masses of tiny bacteria, which then produce waste. (We can talk about waste, right?)

The waste is broken down into a substance that plants can absorb. It acts as plant food and feeds your plants, keeping them thriving. So, microbe waste is plant gold.

What healthy soil looks like

Healthy garden soil supports plant roots and provides them with access to nutrients, water, and air. It is fast-draining yet moisture-retentive, neither too dense nor too loose. Most roots grow in the upper layer (topsoil), which is especially biologically active—home to earthworms, microbes, and other beneficial organisms.

In the topsoil, earthworms improve drainage and aeration as they tunnel, while their castings add nutrients. Organic matter such as ground bark and vegetable matter decomposes, creating a soft, dark substance called humus. Below the topsoil is the subsoil.

Digging deeper: Know your soil

So, let’s learn more about your soil and how it affects how plants grow. Do you have clay or sandy soil? Is your soil acidic or alkaline? Is it thin or rich in nutrients? We’ll review three important components:

• Soil type

• Soil pH

• Soil nutrition

Soil type

There are three types of rock particles: large (sand), medium (silt), and small (clay). Usually, the soil is a mix of these particles. The mix of particles will affect how water drains, how much oxygen plant roots get, and how well the soil holds nutrients.

• Clay soil: Very fine particles are slow to absorb moisture or to drain. Clay soil holds its shape when rolled into a ball. It can become very hard in summer and waterlogged in winter.

• Sandy soil: Large particles drain quickly. Sand does not hold onto nutrients very well, but it warms up quickly in spring.

• Silty soil: Smaller particles than sandy soils with a slightly slippery, floury feel. It holds moisture and nutrients for longer.

Soil pH

Soil pH is the third and last component of healthy soil and affects the availability of nutrients and minerals in the soil, as well as how well a plant can access, absorb, and regulate these materials. A very high or very low soil pH will result in nutrient deficiency or toxicity, leading to poor plant growth.

Soil nutrition

Plants’ primary nutrients are nitrogen (N), phosphorus (P), and potassium (K). On the package of fertilizer, you’ll see these three values separated by dashes (N-P-K); the numbers of each nutrient indicate the percentage of net weight contained.

• Nitrogen (N): Promotes strong leaf and stem growth and a dark green color. Add aged manure to the soil and apply seaweed, fish, or blood meal to increase available nitrogen.

• Phosphorus (P): Promotes root and early plant growth, including setting blossoms developing fruit, and seed formation. Add fast-acting bonemeal or slow-release rock phosphate to increase phosphorus.

• Potassium (K): Promotes plant root vigor, disease and stress resistance, and enhances flavor. Add greensand, wood ashes, gypsum, or kelp to increase potassium.

Soil techniques

Discusses the best ways to prepare your garden bed for planting, such as rototilling and hand digging. This section also covers the importance of installing a mowing strip around the garden bed to keep grass from growing where your flowers are.

You’ll also want to turn to this section for tips on special soil techniques, such as double-digging for high-performance beds like rose gardens and creating raised beds for very poor soil conditions.

Good soil is a work in progress

If the soil in your yard and garden isn’t ideal, don’t worry. Most soils need some improvement.

As a general rule, avoid planting in areas that are soggy or occasionally have standing water. To make these areas suitable for most types of plants, you’ll need to change the grade or add a curtain drain to help remove the excess moisture.

Where winters are wet, working the soil in early spring can leave you with hard clumps that are difficult to break up. Give the soil some time to dry out before you start digging. To check, squeeze, and release a handful of soil. If it crumbles, it’s ready to work.

Start by removing any grass or weeds that could compete with your bulbs or plants. Creating a weed-free planting area saves hours of work down the line. Next, loosen the soil with a spade or garden fork. Dig down 10 to 12 inches and gently lift the soil to incorporate air. Break up any clumps and then rake the area smooth.

Adding organic matter such as peat moss, compost, or shredded leaves is an effective way to lighten heavy soils and improve soil fertility. These can be incorporated in either spring or fall. Mulching around plants with bark chips, pine straw, or leaf mold will also improve poor soil. As these materials gradually break down, they can be mixed into the soil to improve its texture, feed soil microbes, and provide essential plant nutrients.