What is the best vegetable garden soil?

What is the best vegetable garden soil?  In this article, I’m going to teach you about the 3 main components of soil and what the best vegetable garden soil is.  I will also help you understand what you can do to your soil to improve it if it is not the best.  We will also cover what is the best soil for raised bed vegetable gardens.

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What is the best vegetable garden soil?

Vegetable garden soil comes in all shapes and sizes, from heavy clay to sand, to perfect loam.  In order to understand what the best vegetable garden soil is, it is helpful to first understand the major soil components.  So let’s talk about the 3 major soil components starting from the smallest to largest. Everyone’s soil will contain all 3 of these components in differing percentages.

Clay

Clay is the smallest particle in soil. Characteristics of clay include:

• Sticky feel when wet
• Slow water intake
• High water holding
• High nutrient storage

Because clay particles are so small they are often very compact.  Soils that are heavy in clay will be hard to work, plants can struggle to get enough oxygen and to put down deep root systems.  But clay soil does hold water well and is usually loaded with nutrients.

Silt

Silt are medium sized soil particles. Characteristics of silt include:

• Smooth when dry
• Intermediate water intake
• Intermediate water holding
• Intermediate nutrient storage

Silt is an important component of health garden soil.  It helps to balance out the smaller and larger components of the soil.

Sand

Sand is by far the largest particle in the soil.  These sand particles are usually so large that the individual particles can be seen with the naked eye (unlike silt and clay).  Characteristics of sand include:

• Coarse
• Rapid water intake
• Low water retention
• Low nutrient storage

Gardening in soil that is heavy in sand can offer the biggest challenge, simply because it is so hard to keep wet and so low in nutrients.

The Perfect Mixture of Soil Components – Loam

The perfect mixture of soil components is roughly 40% sand, 40% silt, and 20% clay.  We call this type of soil Loam.

What Else is in Your Soil?

On top of the 3 main soil components, there is also a lot more in your soil.  Your soil will also contain some level of organic matter.  Organic matter can be composed of many things like:

• Decaying plant, insect, and animal material
• Bateria
• Fungi
• Nematodes
• Protozoa
• Worms
• Insects
• Mammals

Organic material (especially decaying plant material) is super important to the overall health of your vegetable garden soil.  A good healthy soil may have as much as 5% of its total volume as organic matter.

How do I know what type of garden soil I have?

Testing your soil will help you determine what type of soil you have in your vegetable garden.  Soil test kits will tell you your soil composition and many will also give you some basic information about your soil nutrients as well. 

There are a few ways you can know what type of soil you have in your vegetable garden. 

Soil Test Kits

There are several commercially available soil test kits on the market.  These tests are a good way to get a basic understanding of your soil.  Although not perfect they are a good starting point for the do-it-yourself type gardener.  

Here are a few soil test kits you can buy online.

• Luster Leaf 1601 Rapitest Test Kit
• MySoil-Soil Test Kit
• Soil Savvy – Soil Test Kit

Extension Agency Soil Test Kits

A better way to have your garden soil tested is to send a soil sample into your states extension agency lab.

Most agricultural colleges in North America offer soil testing through their local extension agencies.  You can contact your local extension agency and get a soil test kit from them.  Then take a sample of your soil and send the soil test kit into their lab and for a fee, they will give you a report back on what type of soil you have and also include a breakdown of many common soil nutrients.

Find your local extension agency on this website.

A Simple At Home Soil Test

If all you are interested in is a rough estimate of your soil composition then there is a simple at-home test you can do that will give you a rough idea.

Add a cup of garden soil to a clear glass jar with a lid.  Then add water to the jar so that the soil is all covered.  Put the lid on and shake the jar for about 30 seconds.  Let the jar sit for 24 to 48 hours.

Your soil will then settle in layers.  The bottom layer will be sand, the next silt, and the top will be clay.  You can then measure the layers to get a very rough estimate of how much of each is in your soil.

So you don’t have perfect soil, what next??

Most vegetable gardeners don’t have perfect soil, so don’t worry if yours isn’t ideal.  Your soil test kit should give you some ideas of where to start by telling you your soil composition.  There are some things that you can do to improve your vegetable garden soil organically and it all starts with organic matter. Adding organic material in the form of compost or manures will help to improve your soil structure and fix some of its shortcomings.

Remember that you can’t fix your soil by adding missing components (for example you can’t add more sand to clay soil and expect improvements). You are stuck with the soil composition you have. The way you improve your soil is by adding organic materials and possibly missing nutrients.

Using Compost to Improve Vegetable Garden Soil

Compost is king when it comes to improving your garden soil.  If you have sandy soil adding compost will add nutrients and help with water retention.  If you have clay soil the compost will help break up the soil structure, add air to the soil, and give plant roots room to grow.  Even if you have perfect loam soil adding compost will help maintain that soil and add nutrients.

If you are just starting a new garden then I recommend adding a thick layer of at least 4 inches of compost and mixing that into the top 6 to 8 inches of your soil.  This is one of the few times that I would recommend using a tiller in your garden.  That will help mix the compost deeply in the soil.  After that first application deep tilling shouldn’t be needed.

Going forward you should add a little compost to the top few inches of the soil every time you plant.  And a good thick layer of compost as a top dressing or mulch will always slowly benefit your soil.

Using Animal Manures in Your Garden

Animal manures can also be a great way to add nutrition and organic matter to your soil.  Manures are heavy on organic material and usually add a large amount of nitrogen to the soil.

However, there are a few things you need to be careful with when using manures.

First, fresh manures can be “hot”.  This isn’t in reference to the manure’s temperature, but instead to its nitrogen content.  Adding fresh manure to a garden can cause nitrogen burn to many plants so it is always a good idea to use manures that have been aged (or composted) for at least 6 months.

Second, be careful of your source.  If at all possible get manures from organic producers.  This assures you that herbicides were not used on the animal feed.  Some herbicides can persist even after passing through an animal’s digestive tract and then if you add that manure to your garden it can kill your plants.  

Using manure sourced from poultry or rabbits, that has been composted for at least 6 months can help alleviate this problem.

Adding Rough Organic Materials to Your Garden

You can add other rougher (uncomposted) materials to your garden by using the trench composting method.  

Trench composting involves digging a trench about 12 inches deep and then adding about 6 inches of rougher organic material to the trench and then burying it.  You can add things like grass clippings, leaves, and plant-based food scraps to these trenches.  Over the next few months, those materials will decompose and enrich the soil.

You can learn more about trench composting and how to do it by reading this article which includes a 10 minute video I filmed on the topic.

What is the best vegetable garden soil for raised beds?

Garden soil for raised beds is a different matter altogether. Since you are starting a raised bed garden as an empty box you are able to add the soil of your choice and this helps you control the quality of the soil in your garden.

There are two different methods when it comes to what to fill your raised bed garden with.

Filling a Raised Bed Garden with Topsoil and Compost.

The first idea you can use to fill your raised bed garden is filling it with a 50/50 mixture of screened topsoil and compost.  This is the method we have chosen to go with for our raised beds in our current garden.

This mix of compost and topsoil gives your plants plenty of nutrition and the topsoil adds some structure to soil giving taller plants more support and a little more for the roots to hang on to.  

Each year you should amend the soil in your raised bed with a few more inches of compost mixed into the top few inches of the soil.  Or even easier you can plant your crops and when they have started to grow “top dress” the beds with 2 to 4 inches of compost as a mulch that will break down over the season and enrich the soil.

Filling Your Raised Bed Gardens with a “Soil-less Mix”

The other method for filling your raised bed gardens is to use a soil-less mix.  These mixes usually include the following:

• ⅓ Peat Moss (or coconut choir)
• ⅓ Organic Compost
• ⅓ Pearlite (or Vermiculite) 

Each year, after the first year, you will amend the soil with more compost.

These mixes have the advantage of high nutrition and loose, easy to work with soil.  

The disadvantage of these soilless mixes are that they are so light that I have found some taller plants have a hard time standing up to strong winds.  Also over the years, these mixes break down and eventually have to be replaced (usually in 8 to 10 years).

This type of mix is very popular with folks who garden using the Square Foot Gardening method.

The Best Vegetable Garden Soil

I hope this article has helped you understand what is the best soil for your garden.  Ultimately, whatever type of soil you have you can work to improve it by adding compost and other organic materials to help make it more productive.