Healthy Soil: The Foundation of All Your Landscaping Efforts – Part 1

Healthy soil is critical to the success of your garden. When soil composition is correct, garden plants thrive; when it is not, they struggle.

But how do you know whether the soil is good? And what can your landscape maintenance company do to improve it and enrich it? Understanding the elements of good, rich soil will help you make informed choices when working with a garden designer or landscape specialist.

Why Healthy Soil Is Important to Your Landscape

Healthy soil is much more than just “dirt.” It’s nature’s growing medium for plant life, containing an essential combination of ingredients that plants need for survival. Good soil contains

• minerals and stone particles that provide physical structure to stabilize the plant and hold the roots in place
• water, air, and essential nutrients
• living organisms such as mycorrhizae which has a symbiotic relationship with plant roots and enhances the plants’ ability to take in nutrients and water.

There is a lot of vital activity going on underground in the “unseen garden” that makes our landscapes so captivating to look at. Healthy soil is living soil.

Soil Characteristics and the Effect on Plant Vitality

Developing rich, balanced soil for your garden or landscaping depends on several factors. If any of these factors is off, your plants won’t grow as rich and full as you desire.

1 Soil Composition

Different plants thrive on different soil types. We typically categorize soil as either clay soil or sandy soil based on its consistency and ability to hold moisture and nutrients.

Some plants prefer dense soil that holds onto moisture longer, while others like sandy soil that drains more quickly. Soil that is rich in clay can be dense because the clay particles are very small. This causes water to drain slowly. Sand particles are larger and loosely packed, so it drains quickly.

Good, healthy soil is all about balance. If your soil consists only of clay, it can lead to problems because clay is so dense that it sticks together and gets hard when it dries. Plants need air just as much as water. If the soil consists of too much clay, the roots stay saturated and can’t breathe. Sometimes a landscape specialist must amend the soil to provide a better balance of moisture, nutrients, and air.

By contrast, sandy soil drains quickly and does not retain excess moisture around the plant roots. This type of soil is great for plants that require minimal moisture and nutrients, but if the soil is too sandy, it may be difficult for plants to retain the moisture they need—so sometimes sandy soil must also be amended.

2 Soil Drainage

Optimal soil drainage means moisture drains neither too quickly nor too slowly. If drainage is out of balance in either direction, it puts the plants under stress. Soil that stays too dry doesn’t retain moisture long enough for the plants to absorb it. Conversely, soil that is too wet can cause root rot.

Good drainage can also be affected by factors like slope, evaporation through sunlight, and the presence of other plants. Azaleas, for example, like well-drained soil. They tend to decline in soil that is too rich in clay because the roots start to rot. They are a part sun/part shade shrub, which means they won’t bloom as well in a dense shade setting and will stress out if they get full sun all day. For this reason, azaleas often do quite well on a hillside or as an understory plant among large deciduous trees whose roots pull some of the moisture away. Both situations create more drainage so the plant can thrive.

3 Topography

Topography also plays a role in providing optimal soil conditions. While water often gathers at the bottom of a hill, the high side of a slope tends to dry faster, especially if it gets a lot of sun. Slopes sometimes have poor soil because homebuilders cut into them during construction, excavate the native soil away, and replace it with fill dirt.

If there is a lot of clay content on a slope, water can’t penetrate into the earth. So it runs downhill faster than plant roots can grab it. If the soil on a slope is too sandy, the water runs right through it before most plants can take it up. An experienced landscape specialist can help you identify solutions when the topography of your garden is affecting the soil’s ability to nourish the plants.

4 pH level

The pH factor is a measurement of the activity of hydrogen ions in the soil. A pH level of 7 is neutral. Higher than pH-7 is alkaline; lower is acidic.

Hydrogen ion activity determines a plant’s ability to take up certain nutrients. Most plants want soil that is at or about pH-7 because that is the point at which all the nutrients are most available at the same time.

There are, however, exceptions. Azaleas and the rhododendron family prefer acidic soils (around pH-6) because they need more iron, and iron is more available when the soil is acidic.

If soil is too alkaline, plant leaves will fade, become lighter green, or become chlorotic (i.e., yellowish between the veins). Over time, they will become more susceptible to insects or drought.

5 Compaction

Soil that is walked on or driven over repeatedly becomes compacted. When soil is compressed because of weight, its capacity for water retention and root growth is reduced.

Soil test results can reveal whether the soil has a tendency to become compacted. The percentages of sand, clay, loam, and silt are given a number on a scale called the CEC (cation exchange capacity). The CEC number indicates the soil’s ability to hold water and nutrients as well as its tendency to become compacted. A high CEC suggests the soil has a good holding capacity for moisture and nutrients. The downside to soil with a high CEC is that it is vulnerable to compaction due to heavy foot traffic or mowing. This is why mowing in different directions is recommended to avoid tire ruts.

Maintaining the Perfect Balance

When you have these various soil factors in proper balance, it creates perfect conditions for your garden to thrive. Soil health and vitality naturally change over time. Keeping your gardens and landscape performing at their best requires ongoing care and attention.

A comprehensive garden management program can identify problem spots, provide solutions, and help you maintain the conditions needed for the long-term health of your garden. In part two of this article, we’ll look at the ways landscape maintenance can improve the performance of your soil.

Perhaps you’ve been wondering how to bring out the fullest expression in your landscape and gardens. Our eBook: Choosing the Right Kind of Landscape Maintenance Firm, is full of valuable information to help you understand the fundamental differences between landscape maintenance companies.