Unlike the many elements of your garden you can’t control: The weather, the weeds that never quit, etc.— the quality of your garden soil is actually one of the few elements you can change. Not only that, but it’s a relatively straightforward thing to do that can significantly improve the overall success and bounty of your garden. So if you’ve been wondering how to amend your soil for a healthier garden— you’ve come to the right place. Here’s everything you need to know about soil amendment and soil structure, plus our step-by-step guide to improving your garden soil.
- What Does it Mean to Amend Garden Soil?
- Types of Soil Explained
- How to Improve Your Garden Soil (Step by Step)
- Soil Amendment FAQs:
- The final word
What Does it Mean to Amend Garden Soil?
Before we get into the details on how you can best amend your garden soil, it helps to know a bit about what amending soil actually means. When you amend garden soil, you’re basically just improving it by adding certain kinds of organic material according to your soil’s specific deficiencies.
Most garden soils are imperfect and will benefit from adding organic fertilizers or compost mixes. But to truly amend your soil the right way, you’ll need to understand a bit about what your soil is lacking (or has too much of) and how you can go about fixing it. Rather than just sprinkling a random fertilizer into your garden, it helps to first take the time to study your soil and come up with a game plan of what you’d like to improve and how you’re going to do it.
Why Good Garden Soil Matters
Having good garden soil matters because it’s the nutritional foundation of your garden. Besides whatever they may gain from water and sunlight, your plants rely heavily on the quality of your soil to fulfill their nutritional needs. If your soil is lacking in accessible nutrients, your plants will suffer.
Beyond the nutritional value of soil, you also want to consider the structure of your soil—since this is also important for healthy plant and root growth. We’ll get into some basic soil science next.
Basic Soil Science
When talking about good garden soil, the topic is two-fold. The first thing to consider is your soil pH, which determines just how acidic or alkaline your soil is. This bit of soil science is important as it allows you to understand what kinds of plants will grow best in your garden and which ones won’t. If you’re unhappy with the pH of your soil, you can amend it by adding in lime to increase the pH or sulfur to lower it.
The second bit of soil science you’ll want to understand has to do with your soil’s composition, also called soil structure. This aspect of soil science describes the size of your soil particles and how much space (for air and movement) is in between those particles. It also describes how easily (or not) water gets absorbed into the soil. The main types of soil structure are sand, clay, silt, or some combination thereof. Ideal soil structure is typically described as “loam” which is regarded as a perfectly balanced soil structure in the middle of the aforementioned three types.
Types of Soil Explained
Knowing which type of soil suits a particular plant is extremely important because the soil is crucial to a plant’s survival. It’s the soil that anchors and protects the roots of the plant, allowing it to absorb water from the ground. Soil can also contain lots of nutrients and minerals that help the plant to grow.
Different types of soils have different qualities when it comes to airflow and moisture retention. Some plants like well-aerated soil that drains water quickly. Others prefer denser soils that hold a lot of moisture for long periods.
Six main types of soil are recognized by most horticulturalists. The size of individual soil particles usually categorizes each type of soil. The smaller each soil particle is, the denser the soil becomes.
Denser soils provide less space for air or water to pass between the particles. Dense soils also compact more quickly, making it harder for a plant’s roots to grow. Soils that have larger particles provide more airflow and drain faster.
Common Types of Soil:
- Chalky soils: These soils vary wildly in density and can be light or dense. Chalky soils typically have a more alkaline pH than most other soils. Chalky soils lack nutrients and often contain a lot of stones.
- Clay soils: Clay soils have the smallest particle size of any soil and are incredibly dense. Clay soils are excellent at retaining moisture and nutrients. However, these slow-draining soils take a long time to warm up enough to plant safely.
- Loamy soils: Often described as the perfect soil, loamy soils combine the qualities of clay, sand, and silt. Loamy soils are easy to dig and drain well yet are still fertile and contain lots of nutrients.
- Peat soils: Although not often found in backyards, peat is used extensively in compost. Peat is mainly comprised of organic matter and retains moisture well. However, peat soils are acidic and lack nutrients.
- Sandy soils: Sandy soils are loose, gritty soils with large particles. This makes sandy soils easy to dig and very well-draining. However, sandy soils lack nutrients and will also start losing what little nutrients they have when it rains.
- Silt soils: Silt is formed from tiny particles of rocks and minerals. These soils are well-draining but can still hold a good amount of moisture and nutrients. However, silt soils can easily become compacted.
How to Improve Your Garden Soil (Step by Step)
Assess your soil
The first step in amending your garden soil is to determine exactly what it needs and what your goals are. These will depend in part on what you plan on growing in your soil. If, for example, you want to prepare a garden bed for veggies, this might be slightly different than if you want to prepare your soil for planting a large shrub. Keep in mind that most plants thrive in slightly acidic, rich, well-draining soils (i.e. loam). If you’re not sure of the exact specifics of what your garden lacks, this can be a good general goal to aim for.
Test your soil
If you genuinely want to get into the technical aspects of your soil and its needs, now’s a good time to order up a soil test. You can get one by looking up your local USDA extension office to see what their protocols are for soil tests. Most have online instructions and an address to mail in your samples, and they cost anywhere from $7 to $10. Alternatively, you can also try this basic at-home testing using vinegar and baking soda to get a rudimentary understanding of your soil’s pH.
If you can’t tell the structure of your soil just by looking at it (or asking a fellow gardener), try this easy-at-home test to get an idea.
Buy the necessary amendments
Once you understand what your soil needs (and how you’d like to improve it), it’s time to purchase a soil amendment. This will vary depending on what kind of soil you already have and what you plan on using your garden space for, but again— a good rule of thumb is to always add in nutrient-rich, organic material. If you can sync up with a local farmer to purchase some of their aged manure (make sure it’s been sitting for a while otherwise, it will be too strong for direct use) or some of their compost mix—even better.
When in doubt, “garden soil mixes” sold by local nurseries, manure mixes from turkeys, goats, or chickens, or even a lightly processed compost (we like Eko Compost) will do just fine. Make sure you buy enough amendment material to be able to adequately mix it into the first 16 inches of topsoil at a ratio of ⅓ amendment to ⅔ native soil.
Gather your tools
With your amendment materials ready, it’s time to gather up the other tools you’ll need for the job. For this, you essentially want tools that allow you to dig and mix your soil easily. A hand trowel and wheelbarrow might be enough. As an alternative (particularly in rocky or clay-soil gardens), digging might require a pick-ax and much larger shovels.
My personal favorite tools to have on hand include garden gloves, a pick ax, large shovel, a hand trowel, a small hand rake, and a bucket. With these tools, I’m able to dig into the topsoil, remove it into my bucket, mix in the amendment, then add it back to the soil. Having the pick ax and larger shovel on hand help with digging, but also if you run into any large rocks (a near certainty in my garden)!
Break up the ground
The first step in amending your soil is to break up the topsoil. If you have mulch, be sure to rake it aside before starting this step, as you don’t avoid mixing mulch into your soil as much as possible. This is also an excellent time to remove any unwanted rocks, debris, or weeds from your garden soil.
Add in your soil amendments
Once you’ve broken up the soil, you can add in your amendments in one of several ways. The first way (my personal favorite) is to use a bucket or wheelbarrow and scoop your native soil into the vessel and add in your amendment. Using a ratio of ⅓ amendment to ⅔ native soil seems to work well and will make a significant enough change in your soil without shocking the root systems of your established plants. This method allows you to really get a good look at the state of your current soil and stir things up with your hands. You can also sift out any rocks or weeds that you didn’t catch previously.
If you don’t have a wheelbarrow or bucket on hand, you can still do the same process directly in your garden soil by adding in enough amendment and stirring it up with your hands or tools.
Cover your soil
While this isn’t strictly part of soil amendment, it’s a good final step to take in ensuring the ongoing health of your soil. The reason? One of the worst things you can do for your soil (especially when you’re trying to improve it) is to leave it the top layer bare— which leads to dried out, nutrient-deficient soil.
So before you pack up your gardening tools and call it a day, add a bit of mulch to your newly amended soil. This can be natural mulch you find around your yard (like leaves or pine needles) or the fancier stuff you get from the garden store. Alternatively, if you’re not a neat-freak gardener, you can also consider planting some cover crops that will enrich your soil, add nutrients back into it, and can make for tasty toppers on your summer salads. Some favorite and easy-to-grow cover crops include clover, arugula, mustard greens, and alfalfa.
Soil Amendment FAQs:
1. How should I amend my soil?
Amending your soil all starts with understanding what you’d like to change about it (the pH, the structure, or both) and how you’d like to go about doing it. If deep diving into the science of your soil isn’t feasible, a good standard is to start by adding nutrient-dense organic compost or soil mix at a ratio of ⅓ amendment to ⅔ native soil.
2. What is the best soil amendment?
There’s really no “best” soil amendment. But for adding more nutrients back into your soil (which is usually a good idea no matter what), we really like Eko Compost or Miracle-Gro Potting Mix.
3. How do you amend soil in an existing garden?
You can amend the soil in an existing garden by mixing in nutrient-rich compost or other organic soil mix purchased from local farms or nurseries. To do this, start by digging up a small section of unplanted garden soil (be careful not to disturb the roots of your existing plants) and stir in your amendment at a ratio of ⅓ amendment to ⅔ native soil. Add fresh mulch to your soil when finished.
4. What can I add to my garden soil to improve it?
Adding more nutrient-rich organic matter will almost always improve the composition of your soil as well as its overall health and function. You can do this with aged manure or organic compost, or garden soil mixtures.
5. How can I improve my garden soil cheaply?
Improve your garden soil on the cheap by adding in aged manure or compost from a local farmer. You can stir these amendments directly into your soil at a ratio of ⅓ amendment to ⅔ native soil. Be sure to cover your soil afterward with fresh mulch (or leaves or pine needles) to lock in the moisture and keep it from baking in the sun.
The final word
While it does take a bit of time and effort, amending your soil is a worthy endeavor for any gardener. By improving the nutrition and composition of your soil, you’re almost guaranteed to have healthier, stronger plants—without the use of added chemicals or synthetic fertilizers. Prioritize amending your garden with organic materials, and you’ll be amazed at how intelligently your garden adapts to these nutritious additions and how happy your plants are.
To learn even more about soil science, check out the book Teaming with Microbes: The Organic Gardener’s Guide to the Soil Food Web by Jeff Lowenfels.
Larissa is a writer, gardener, and herbalist living in the San Juan mountains of Colorado. Her writing has been widely published in lifestyle and personal finance publications all over the country, and she's also the creator of the weekly newsletter @rootedintribe.
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