Feb 9, 2021 10:46:05 AM / Brooke Loeffler /

Soil Amendments

A successful garden always begins with good soil. So, whether your green thumb is just getting going or your seasoned garden needs a checkup, here are some helpful tips to start this growing season off right.

What Is Good Garden Soil?

Garden soil provides an environment for a plant’s root zone and that:

  • Stabilizes the plant
  • Channels nutrients, water, and air to the roots
  • Nurtures helpful organisms that aid plant growth

In order to accomplish these goals, healthy soil must have 2 main qualities:

  1. Correct fertility levels (a combination of soil pH and nutrients)
  2. Correct texture (a combination of particle size and cohesiveness)

Soil Amendments

Soil fertility and texture can be adjusted by using soil amendments. Amendments are any added organic or inorganic materials that make your soil a better environment for your roots. Soil amendments can improve nutrient levels, permeability, pH, water retention, and more. It is important to remember that your soil will gradually revert back to its original state and needs occasional checkups. Click here to learn more about how nutrients are continuously stripped from soil.

Testing Your Soil

Hands holding a plant and soil

The first step to healthy soil is to eliminate guesswork and find out what you’re dealing with. Using amendments before you know your soil quality can do more harm than good. Fortunately, there are a few soil testing options available.

Local Ag Extension

If you are looking for a thorough and comprehensive soil test, turn to your local Agriculture Extension Program (click here to find your local services). For a nominal fee, Ag programs can give you an in depth lab test of your soil’s nutrients, pH levels, and soil type. They will also make recommendations on which amendments to use, quantities, and application rates. In depth testing can set you up with a soil health plan that can benefit your garden for years to come.

Garden Center/At Home Testing

Most plant nurseries and garden centers carry soil testing kits that can either give you quick readings at home or help you prepare samples to send to your local Ag Extension. You can also perform some at home experiments to get a general idea of your soil type and quality.

Amending Your Soil

When adding amendments to your soil, be sure to rake, till, and dig thoroughly to ensure they are dispersed well. Follow packaging instructions to avoid over or under applying. Some amendments may recommend applying in stages to reduce shocking your plants.

Amending Soil pH

Soil pH Scale

Soil pH directly affects the availability of nutrients and minerals to the roots, as well as a plant’s ability to absorb and regulate them. According to Farmer’s Almanac, “a very high or very low soil pH will result in nutrient deficiency or toxicity, leading to poor plant growth.” They recommend home gardens aim for 6.5 on the pH scale. Keeping your soil between 6.0 and 7.0 will also encourage healthy microbial activity in the soil. Some plants prefer more acidic soil, and others more alkaline soil (click here for a list of common plant pH preferences). Once you know what you would like to plant, make sure you research your plants’ specific pH needs.

  • To Lower pH (increase acidity): Elemental sulfur, aluminum sulfate
  • To Raise pH (increase alkalinity): Limestone, untreated wood ash, bone meal

Amending Soil Texture

Soil is made of a mixture of clay, silt, and sand particles. The spaces between these particles fill with water and air to provide plant roots with moisture and oxygen. Sandy soil is looser and doesn’t hold as much water for plants to use. Clay soil is denser and richer, but holds too much water and does not allow for enough oxygen flow.

Amending soil texture

The ideal garden soil is a balance of clay, silt, and sand particles. This balanced mix is called “loam.” Loamy soil provides an ideal environment that both stabilizes the plant and allows for the right level of water retention and air movement around the roots.

What Kind Of Soil Do I Have?

The easiest way to determine your soil type is to dig down several inches, gather some soil, dampen it, and try to compress it into a ball. If it doesn’t compress at all, your soil is sandy. If it  compresses into a hard, solid ball, it is clay heavy. Some plants prefer sandy soil (like cacti and succulents), so be sure to research your plant’s preferred soil type before amending.

Amending Clay Soil

The best way to correct clay soil is to mix in organic materials that loosen your soil to improve drainage and encourage root growth. These amendments also support the growth of helpful microbes that keep your soil healthy. Inorganic materials can also be used to break up and aerate heavy clay. Examples of amendments for clay soil include:

  • Peat moss
  • Compost 
  • Manure
  • Plant mulch: grass clippings, trimmings, and fall leaves 
  • Gypsum
  • Perlite/vermiculite

Amending Sandy Soil

Sandy soils are usually light on moisture and nutrients, so the goal is to enrich and increase water retention. For this reason, the organic amendments listed above for clay soil can also help sandy soil. Sandy soil amendments include:

  • Compost
  • Manure
  • Mulch 
  • Biochar
  • Coconut coir

Amending Soil Nutrition

Some amendments only address soil texture while providing little nutrient value. For example, peat moss is excellent for amending texture but lacks the rich nutrient profile plants need.  Plants require 14 essential nutrients from their soil environment (to see what each of these nutrients provides, click here):

Macro-nutrients (needed in higher quantities)

  • Nitrogen
  • Phosphorus
  • Potassium
  • Calcium
  • Magnesium
  • Sulphur

Micro-nutrients (needed in lower quantities)

  • Chlorine
  • Boron
  • Iron
  • Manganese
  • Copper
  • Zinc
  • Nickel
  • Molybdenum

Many fertilizers focus too heavily on Nitrogen, Phosphorus, and Potassium (N-P-K) while neglecting the importance of the essential micro or trace nutrients. A plant’s ability to absorb, process, and use macro-nutrients depends upon the presence of scarce minerals (see The Law of The Minimum to learn more). Look carefully at soil amendment ingredients to ensure you are providing your plants with a balanced and complete nutrient profile, not just NPK. A soil mineral conditioner not only gives your plants more complete nutrition, they will create a more nutrient dense harvest for you to enjoy.

Redmond Mineral Conditioner

Started by farmers over 50 years ago, Redmond Minerals is happy to share our family of unique, mineral balanced soil products. Our mineral conditioner contains a mix of deep sea minerals and enriching volcanic bentonite clay harvested from our ancient sea bed in central Utah.

Redmond mineral conditioner for amending soilOur soil amending conditioner naturally has a pH of around 7 and has a proven track record among growers of improving soil quality and plant health.  Click here to see the impressive results other growers have enjoyed after using Redmond!