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Green grass and beautiful garden

Soil Conditioning 101: Grow Better Plants & Lawns

Using a good soil conditioner is one of the best things that you can do to grow better lawns and plants. Learn more about what soil conditioners are, how and when to use them, and why they are so important to grow better plants.

Amending your soil for better landscapes

Soil health is perhaps the most important thing for having productive and beautiful landscaping. Bad soil can limit the amount of water and nutrients that your plants can get, leading to poor (or no) growth. And, because flowers, vegetables, and grass use nutrients from the soil to grow, it is critical to replace these nutrients each year.

Soil amendments and, in particular, organic soil conditioners can improve poor soil, replenish nutrients, and lead to better growth for your plants and grass. There’s no magic bullet in gardening, but using a good soil conditioner is certainly up there on any potential list.


What is a soil amendment? What is a soil conditioner? Is this the same as a fertilizer?

Soil amendments is the broadest term since it can be anything that you add to your soil in order to grow better plants. Using this definition, soil conditioners and fertilizers are both soil amendments. In the U.S., a fertilizer is increasingly just a legal term that refers to a soil amendment that will guarantee a minimum amount of (macro) nutrients that are in the package. However, this is not a guarantee of what nutrients will be available to your plants immediately or in the future (if at all).

A fertilizer adds nutrients to the soil while a soil conditioner makes a soil healthier, allowing plant roots to more easily get and use nutrients. It’s not clear cut, however, since some soil conditioners (like our Grow Good Compost) also add macro and micro nutrients to the soil. In contract, most fertilizers don’t improve soil structure and only add macro nutrients.

There are times that you may use both a fertilizer and a soil conditioner in a gardening project but, most of the time, a soil conditioner made from organic matter is all you need for your plants and grass.


What does a soil conditioner do? What is it used for?

A soil conditioner allows your plants to get more water, air and nutrients so that they grow better.

Soil conditioners change your soil’s structure, making it more “crumbly:” for clay soils, it helps break the clay into smaller pieces; for sandy soils, it helps it stick together a little more. The tiny spaces that are then formed in between the crumbs are filled with air and water. This gives your plant roots the physical space to grow deeper and stronger, and is how the roots then access the water, air and nutrients that they need for your plant to grow.

If you’re interested in some of the technical terms, a soil conditioner will improve water retention, water infiltration, drainage, soil permeability, soil aeration, nutrient-holding capacity and organic matter content.


What are the different types of soil conditioner? What is it made of? What’s the best one?

Soil conditioners can be organic or inorganic. Organic amendments are made from something that was alive, and inorganic amendments are mined or human-made.

Organic soil conditioners can include compost, animal manure, human waste (also biosolids or sewage sludge), mulch fines, pine needles, and grass clippings. Peat moss is another option and, while it works really well, its harvesting is usually bad for the environment.

Inorganic soil conditioners can include sand, slate, gypsum, pulverized limestone, perlite, and vermiculite.

Depending on your gardening project, you may need to combine these different options.


How do you amend your soil using a soil conditioner?

When you are creating a new garden or establishing a new lawn, it is best to mix (or till) the soil amendment into the existing soil, usually mixing to a depth of six to eight inches. This will provide a better soil structure and nutrients for your plants or grass, especially where their roots will be.

When you have an existing lawn or garden, soil amendments should be applied to the surface (also called topdressing a lawn or bed) and then watered. This helps to wash any compost off of the grass blades and helps it settle around the base of plants.

A soil test will help you understand the current condition of your soil and, depending on the soil testing that you do, can even recommend the steps you should take to improve your soil. It can help you identify which soil amendments you should use and how much. Given how much money plants cost, these are relatively inexpensive and valuable.

How much soil conditioner you will need depends on the current condition of your soil, the conditioner’s manufacturer, and how you are applying it. Manufacturers frequently provide instructions on their packaging and website, and following their instructions will help ensure that you’re not using too much or too little.


How often do you amend soil?

Plants and grass take nutrients from the soil in order to grow and replacing these nutrients is an on-going process. How you add nutrients to your garden and lawn depends on a number of things, including what you are growing, how you care of it throughout the year (are you adding natural mulch?, grass-cycling?), and the existing health of your soil.

The textbook answer is to do an annual soil test and use the results to determine what soil amendment(s) is right for you and how much you might need. This is the best way to achieve a high-quality landscape. That said, most gardeners are really happy with the results from applying organic soil conditioners to the top of their garden and grass every fall. Depending one what is being grown in a plant bed, people may also top-dress in the spring just before mulching.


What’s the best soil amendment for clay soil?

In Northern Virginia, we have a lot of clay soil that becomes heavily compacted over time. Clay soil is high in nutrients but those nutrients are often locked up and unavailable to plant roots.

It is best to start with an organic soil conditioner so that the clay soil breaks apart, giving your plant roots the space to grow and access to the in-soil nutrients that the clay provides. Over time, you may need to add more soil condition to further break apart the clay and/or a fertilizer, depending on what you’re growing.

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