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What is Garden Soil Exactly?
If you stroll around Home Depot, you’ll see lots of bags marked “garden soil.” Garden soil is a type of soil that is best for planting trees, shrubs, and flowers. The key difference between gardening soil and other types of soil, such as raised bed soil, is that garden soil does not contain organic elements. This means that garden soil is not mixed with manure, fertilizer, or compost. Garden soil is different from potting soil because it is meant for outdoor use and normally has a lower price tag than potting soil.
For planting trees, garden soil has 5 advantages over other types of soils:
- Garden soil is meant to be mixed in with the local dirt.
- Too much nutrients in soil can kill a young tree, so it is best to avoid soils with manure and compost in them.
- It is an ideal weight and density for young trees, allowing them to grow without obstructing their roots.
- Garden soil can be purchased in bulk relatively cheaply, so it is the most affordable way to landscape.
- Insects and worms can safely burrow in garden soil, making it safe for the natural ecosystem.
What Are the Different Types of Garden Soil?
There are 6 different types of garden soil: loamy soil, chalky soil, silty soil, sandy soil, clay soil, and peaty soil. Garden soil is better than raised bed soil or potting soil for planting trees, but it is best to match the type of garden soil to the tree that you are planting.
What is the Best Type of Garden Soil for Planting Trees?
Loam soil is one of the best types of garden soil to plant trees. It is composed of 40% sand, 40% silt, and 20% clay. It has enough nutrients to help a young tree grow, but not so much that it will cause the tree to die. This type of soil has a good balance of drainage and the ability to hold water. This means that the roots will not drown and that the soil will not dry out too fast.
Loam soil can be recognized by its crumbly texture. This allows air to penetrate the soil, as well as for the roots to easily push through the soil.
It is rare for loamy soil to occur naturally in your garden. Creating this type of soil requires a large amount of work over the course of several years. The easiest way to obtain loam soil for your garden is to buy it in bulk from the nearest hardware store. Bags of soil are normally marked as “Loam Soil” or designated as soil “for trees and bushes.”
Which Trees Grow Well in Sandy Soil?
Sandy soil is easy to spot in dry areas. This type of soil contains large amounts of sand mixed with the natural soil. It often looks indistinguishable from sand due to its coarse and grainy texture.
Sandy soil has a loose base and retains water poorly, making it hard for trees to get nutrients. You may look at this soil and assume that nothing can grow in it, but there are several types of trees that will grow happily in sandy soil:
- Red Oak
- Paper Birch
- Yellow Birch
- Bur Oak
- American Arborvitae
- Eastern Redcedar
Since sandy soil has very good drainage, it is a good fit for trees and plants that can survive in dry conditions. For some trees, it may be beneficial to add fertilizer to your sandy soil.
Can Clay Soil Be Used to Plant Trees?
Clay soil is naturally tightly packed, lumpy, and becomes sticky when wet. Because this type of soil is so dense, it has a larger capacity for holding water and nutrients than loam or sandy soil. However, because clay soil is so dense, it can prevent air and moisture from penetrating through the soil. This means that it takes a long time to drain, remains cool year round, and can block roots from growing.
Clay soil can be beneficial for preventing the spread of roots, which may entangle pipes and cause the sidewalk to crack as the tree grows. The best way to do this is to dig the hole for the tree, pack clay soil along the hole, and then use loam soil for the backfill. As the tree’s roots grow and expand, they will have difficulty growing through the clay soil barrier, which will prevent them from causing problems in the long run.
There are a few trees that thrive in clay soil:
- Crab apple trees
- Sorbus, also called Japanese Rowan trees
- Japanese dogwood
- Saucer Magnolia
If you are attempting to grow trees and shrubs directly in clay soil, you will need to frequently add organic matter and fix it into the clay soil. As the organic matter is broken down, it will break up the soil and introduce nutrients.
Which Trees Can Be Planted in Silt Soil?
Silt soil has a slippery texture because it is made up of fine particles. This type of soil has a more root-friendly texture than clay soil and retains both moisture and nutrients almost as well as loam soil. The key to planting a tree in silt soil is to manage drainage by mixing in materials like grass cuttings.
Silt soil is generally better for shrubs, certain types of vines, grasses, and perennial flowers. There are a few types of trees that can grow in silt soil: cypress, dogwood, birch, and willow.
This can be an easier option than clay soil for planting trees, but it will require extensive maintenance. Because silt soil is made up of such fine particles, it erodes easily from rain and wind. If the soil is compacted around the tree’s roots too tightly, it can cut off air, water, and nutrients from reaching the tree.
Can Trees Grow in Peaty Soil?
Peat soil, also called turf, is naturally found in bogs because this type of oil is distinguished by the fact that it contains organic matter. Peat is formed when plant decomposition is slowed down due to the cooler climate; this causes a buildup of carbon in the soil.
There are pros and cons to using peat soil for planting trees. Peat allows the soil to breathe and retains moisture well. It is also acidic, so trees like heather, rhododendron, witch hazel, and lantern trees grow well in peat.
For most landscapers and home gardeners, it isn’t efficient to use peat soil as backfill when planting trees. Unlike other types of soil, peat is a non-renewable resource that is very difficult for humans to recreate.
Are Chalky Soils Safe for Trees?
Chalky soils are alkaline soils that contain large amounts of chalk and limestone. Much like sandy soils, it can be very difficult for most plants to grow in this soil. Even if you periodically add organic material to your chalky soil, it can be difficult to get the soil to hold enough nutrients for a tree.
Due to its inhospitable nature, there are not many trees that can grow and thrive in chalky soil. One option for your garden is the spindle bush, also called the red cascade. It grows along the line between a small tree and a large bush, but can be a valuable addition to any garden because it is hardy, vibrant, and only needs light shade.
The autumn cherry tree, also called the winter flowering cherry, is another beautiful tree that can grow in chalky soil. It requires plenty of drainage in its soil and needs full sun. Autumn cherry trees bloom light pink flowers in both the spring and fall.