How To Plant A Shrub In Clay Soil

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This article provides instructions for planting a shrub in clay soil
by Brett · All Zones · Planting · 0 Comments · August 29, 2012 · 9,562 views

I've been in the nursery and landscaping business in mid-Georgia since the early 1980's. This has provided much experience with planting shrubs in clay or clay-based soils. And there is a difference between the two. From one job site to the next, and even different areas within the same job site, the type of clay soil can vary tremendously. Sometimes, you might find rock-hard or "solid clay** in the front yard and sandy to loamy clay-based soil in the back yard. Regardless of the type, with proper planting techniques you can successfully plant and grow shrubs in any type of clay soil.

How do I know the type of clay soil in my yard?

That's easy. When the soil is damp, dig a handful from the ground and squeeze it in your hand. If it molds in your hand like modeling clay, you have what I call dense clay soil. If it crumbles or falls apart, you have sandy and/or loamy clay-based soil. Dense clay soils are a little more difficult to plant in and will require a different planting method than when planting in sandy or loamy clay soils. Reason being, one provides better drainage than the other. While sandy and loamy clay-based soils typically provide better drainage and provide a better environment for root development, dense clay soil tends to hold water longer during wet weather and is more compact, prohibiting good root development.

Planting methods for clay soils

Dense Clay SoilDiagram for planting a shrub

Dense clay soil is prevalent in many parts of the world. So don't feel like you're all alone if that's what you have in your garden. And, if you do have dense clay, you know it can be a real pain to dig in.

While many trees and shrubs grow well in clay, the roots of shrubs, and most other types of plants, just aren't strong enough to make their way through dense, compact clay. That being said, even dense clay soil has its positives. It retains moisture well and tends to be more nutrient-rich than other soil types. The reason for this is that the particles that make up clay soil are negatively charged. They attract and pick up positively charged particles, such as calcium, potassium, and magnesium, all of which are important for plant health.

What is the best planting method when planting shrubs in dense clay soil? Well, first, if the soil is dry, it can be very difficult to dig in. So much so that sometimes even motorized augers have trouble breaking through it. Of course, you can always hire a contractor to come in with a large piece of equipment or bring in large quantities of higher quality native topsoil soil to build the area up. But sometimes this is not possible or, not to mention, affordable.

So, if you can't or don't want to add topsoil or hire a grading contractor to break things up, you'll be faced with planting one shrub at a time in the dense clay.

Step 1

When planting a shrub or tree in dense clay soil, the rule of thumb is to dig the planting hole at least 3 times the width of the rootball of the plant and maybe 1.5 times as deep. When dense clay soil is dry, this is much easier said than done. In rock hard, dense clay soil, perhaps the best thing to do is use a round point shovel or pick to first dig a small pilot hole. This pilot hole might only be as large as the rootball of the plant, or even smaller. As you remove soil...or should I say "chips"...pile it up around the perimeter of the planting hole. After digging the pilot hole fill it up with water. Allow the water to soak completely in. This could take 12 hours or more if the soil is extremely dense and compact. After the water has soaked in, the soil around the pilot hole should then be much softer to dig in. Dig and remove the softer soil from around the pilot hole. If necessary, fill this larger hole with water again and repeat the process until you have a sufficient size planting hole.

Step 2

After the planting hole is dug, use a round point shovel or pick to chop up the clay soil into as small of pieces as possible. Then thoroughly mix in a good organic matter such as mushroom compost, composted cow manure, bagged topsoil, and/or sand at a 50/50 ratio to the soil removed from the planting hole . If the clay soil you remove from the planting hole is just too hard to break up and mix with soil amendments, bring in some good native topsoil to use as a backfill.

Step 3

To plant, set the root ball in the planting hole so that the top edge is even or slightly above the ground level. If necessary, add some backfill mixture to the bottom of the planting hole to achieve the proper planting depth. Then use your backfill mixture or native top soil to begin backfilling around the rootball, tamping as you go to remove air pockets.

Step 4

After planting. water deeply and apply a 1 to 2 inch thick layer of shredded wood mulch or pine straw around the planting hole.

Sandy or Loamy Clay Soils

Sandy or loamy clay is much looser and therefore much easier to dig and plant in. When planting in looser soils you can use the same method as described above for planting in solid clay, however not as much soil amendment will be required. A good ratio might be one-third soil amendment to two-thirds native soil removed from the planting hole. That being said, if your soil is of good quality, and already rich in organic matter, there might not be a need for any amendment at all.

Note: The above mention planting methods can be used for most types(species) of shrubs. Some types of shrubs may require slightly different planting methods. Always consult with your local nursery and garden center professional about specific planting needs for the shrubs you intend to purchase and plant.


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