Identifying the Best Soil for Outdoor Potted Plants

Identifying the Best Soil for Outdoor Potted Plants
Image: Markus Spiske on Unsplash

As the foundation of your plants, you need to choose the right soil type in order for your outdoor potted plants to properly develop. This is an investment that will determine how well your plants will grow. 

You don’t need to worry as choosing the right soil for your garden doesn’t need to be tricky.

To help you out, we’ve listed our top soil picks for outdoor plants. To boot, we’ve created a comprehensive list of factors you should consider when choosing the best soil type for your outdoor potted plants.

3 Best Soil Types for Outdoor Potted Plants

Best Soil Types for Outdoor Potted Plants
Image: Markus Spiske on Unsplash

The selection of different types of soil in the market can get overwhelming, to say the least. 

Here’s a list of our personal favorite types of soil for outdoor potted plants:

1. Loam Soil

Loam Soil
Image: World Atlas

Loam soil is often referred to as a “gardener’s best friend” and for good reason. It’s the perfect mixture of sand, silt, and clay, which makes it the ideal composition. 

Since it has a mix of both small and large particles, it has a rather loose and crumbly texture. As a result, it provides exceptional structure and support for plants since it isn’t difficult for roots to penetrate through.

It’s also great at holding water and nutrients while providing ample drainage. Its consistency retains just enough water for plants to properly absorb without causing standing water.

Hence, it’s often considered the most fertile type of soil. It’s actually the most common soil type used for garden beds as nearly any kind of plant grows well in a loamy soil.

2. Peat Soil

Peat Soil
Image: Plants Spark Joy

Just as its name suggests, peat soil is made up of peat, which is made up of decayed organic matter. So, you can expect the soil to be laden with a variety of nutrients and minerals.

However,  it’s quite acidic, which some plants aren’t particularly fond of. Nevertheless, you can add glacial rock dust, elemental sulfur, or agricultural limestone to neutralize the pH level.

Peat soil is also great at retaining moisture without holding too much excess water. This makes it a good option for outdoor plants that prefer constantly moist soil. 

Apart from that, its composition also ensures adequate aeration so you don’t have to worry about compaction. This also allows the plant’s roots to grow freely without much resistance. 

3. Silt Soil

Silt Soil
Image: Gardening ABC

Did you know that silt soil is actually one of the most fertile types of soil? Hence, it’s often primarily used for agricultural purposes to enrich the land and improve production.

It’s a popular choice when growing most fruit and vegetable crops because of its high mineral and nutrient content. 

Silt soil is made up of medium-sized rocks and mineral particles. It has a rather smooth texture that’s relatively fine to the touch. 

Because of its composition, it’s able to retain water and nutrients better than other soil types. To further improve this, some gardeners add fertilizers and organic matter. 

It’s known to fall apart quite easily, which makes it easy to work with. However, it’s important to ensure that there’s adequate drainage and enough amendments  to avoid compaction.

How to Choose the Best Soil for Outdoor Potted Plants

How to Choose the Best Soil for Outdoor Potted Plants
Image: Markus Spiske on Unsplash

To choose the best soil for your outdoor plants, consider the wind, rainfall, heat, and insects in your area.

Not only that, you also need to consider soil density, retention, airflow, and nutritional content to determine the best soil type to use to help your plant thrive.

We discuss all these factors (and more!) in this article. Read on to learn more!

1. Wind

Wind
Image: Sinitta Leunen on Pexels

Best Soil Type of Windy Areas: Clay Soil

Wind speed can be unpredictable outdoors, especially if you’re in an area that frequently experiences pressure changes.

Strong gusts of wind can deal great damage to plants with fragile and thin root systems. They can be easily knocked over or even completely plucked from the ground.

To firmly secure your plant, you’ll need to use soil that provides enough security and anchorage. You’ll want to pick out medium-weight potting soil that will help make your plant less vulnerable to wind damage. 

Aside from that, the soil will need to be a tad more dense than normal gardening soil. This prevents severe soil erosion as it won’t be easily blown away.

Having said that, the ideal soil type for windy areas is clay soil since it’s dense and compact enough to hold itself together. Hence, it provides substantial structural stability.

Other than that, clay soil is great at naturally retaining water which makes it an optimal choice if you’re looking for a drought-resistant option.

It also has substantial nutrient content and holding capacity. As a result, it’s an ideal selection for nutrient-hungry plants.

The biggest con about using clay soil is that it has a tendency to hold too much water, causing it to be compacted, heavy, and water-logged. This could inhibit the circulation of oxygen and nutrients.

To combat this, you’ll need to make certain that the soil is still light enough to drain excess water. Even then, you don’t want it to be too soft and airy that your plant can topple over from its own weight.

Planter’s Tip: 

To increase aeration in your soil, add amendments such as:

  • Sand
  • Composted bark
  • Sawdust
  • Manure
  • Perlite

2. Rainfall

Rainfall
Image: Mike Kotsch on Unsplash

Best Soil Type of Rain-Prone Areas: Sandy Soil

Another major consideration to take into account when choosing the most appropriate soil type for your outdoor potted plants is the amount of rainfall that your area receives.

While you can predict how much water you give your plants during watering, it’s rather difficult to anticipate the volume of water during rainfall. 

Apart from choosing a pot that has adequate drainage, the type of soil it has will also play a role in determining whether your container will have any standing water.

Dense soil doesn’t have that many pockets of space, which makes it more susceptible to water retention. Pots that are constantly wet will encourage the growth of diseases and bacteria. 

Apart from that, it’s also easier for dense soil types to compact as large amounts of water cause the soil to get heavier. This cuts off the circulation of oxygen in the soil, which could ultimately suffocate your plant.

Having said that, the best type of soil to use for areas that frequently experience rainfall is sandy soil. This is because they have a low water-holding capacity, which makes draining and drying a breeze.

But here’s the hitch: they don’t hold nutrients well. It doesn’t help that rainfall tends to wash away the nutrients in the soil, too.

A quick fix would be to add fertilizer and organic matter to help enrich the soil, making it more balanced and fertile. Take note that these will be most effective when applied on sunny days to give the soil and plant ample time for absorption.

Planter’s Tip: 

Add vermiculite to your soil to help with nutrient retention and aeration. 

It contains several essential nutrients to help boost your plants growth, namely – ammonia, calcium, potassium, and magnesium. It’s also porous and comes in unique shapes, which helps trap water and hold moisture in.

3. Sunlight and Heat

Sunlight and Heat
Image: Kelly Sikkema on Unsplash

Best Soil Type for Areas with Extreme Temperatures: Loam Soil

Extreme temperatures can turn your fertile soil as dry as a desert in no time, especially if your area is prone to drought and dry spells.

Apart from proper watering and providing ample shade, you’ll also want to use the right soil to ensure that your outdoor plants don’t shrivel up from the heat. 

To be specific, you’ll want to use soil that can easily absorb water and retain moisture. This ensures that there’s enough water in the soil for your plant to thoroughly absorb. 

In this case, loam soil is the best option as it’s made out of a mix of sand, silt, and clay. This well-balanced combination makes it a nutrient-rich soil that’s easy to work with.

Take note that clay is a dense soil type that retains too much water. Meanwhile, sand has a poor water-holding capacity, which will make your plant even more susceptible to drying out.

Since loam soil contains both of these along with organic matter, it makes an ideal blend for a fertile, all-around soil type. It holds moisture well while providing adequate air circulation, which prevents it from easily drying out in warm temperatures.

If you’d like to take it up a notch, you can further improve the quality of loam soil by adding beneficial organic matter. Here are some ingredients that you can incorporate that would yield benefits to your soil:

  • Compost
  • Dried leaves
  • Grass clippings
  • Shredded tea bark
  • Mulch
  • Manure

4. Insects

Insects
Image: Thomas Park on Unsplash

While there are a handful of beneficial insects that can do wonders for your garden, you’ll need to keep an eye out for pests that can easily wreak havoc on your plants.

There are certain soil borne insects that make themselves at home inside your soil. This gives them easier access to feast on your plants.

Unfortunately, there are cases wherein ready-made potting soil is infested with the eggs and larvae of harmful insects.

For example, peat moss is a common ingredient in most potting mixes. While it’s a great soil amendment, it’s also known to attract fungus gnats whose larvae can harm the roots of your plant.

Having said that, it’s important to know what elements in your soil are known to bring in insect pests to your garden. 

To give you a better idea of what to expect, here’s a comprehensive table of various elements found in soil along with the kinds of insects they tend to attract.

Soil Mix IngredientsCommonly Soil Insect Pests
SandMole cricketsTiger beetleAnt lion (larva of the owlfly)
CompostAntsEarwigsSow bugsPill bugsSlugsSnailsTermites
Peat moss or sphagnum mossFungus gnatsSpider mitesAphidsThripsMealybugs
Coco or coconut coirFungus gnats
MulchSowbugsEarwigsCarpenter antsTermites

5. Soil Density

Soil Density
Image: Markus Spiske on Unsplash

It’s important to consider the soil type’s density as it’s a reflection of the soil’s overall health. It also determines the soil’s ability to hold water, penetrability, and porosity, among others.

While the concept of soil density may seem intimidating, it’s actually a relatively simple idea. 

In simpler terms, it’s the amount of pore space present in the soil that allows water, nutrients, and oxygen to easily travel through. 

Soil compaction (how to prevent soil compaction in pots) happens over time, especially in potted plants, due to several reasons. This includes poor watering habits, lack of soil amendments, and inadequate drainage, among others.

Your soil becomes denser as it becomes compacted. This happens when pore space becomes reduced, leaving little to no room as particles are closely packed together.

Depending on environmental circumstances, you’ll want to pick out a soil type that won’t compact easily. 

Say, if your garden frequently experiences heavy rainfall, you’d want to avoid using clay-type soil as it tends to hold on to excess water.

Planter’s Tip: 

To avoid compaction for any type of soil, add natural soil looseners such as earthworms and soil amendments such as peat moss, coconut coir, and horticultural sand to naturally help aerate the soil. 

6. Retention

Retention
Image: Alicia Christin Gerald on Unsplash

Depending on how much water your outdoor potted plants will receive, you’ll also want to factor in which soil type retains the water and nutrients the best.

Since clay soil is made up of smaller particles, it has the largest water-holding capacity as there’s less space for anything else to move. 

Meanwhile, sandy soil has the lowest water-holding capacity since it’s made up of relatively large particles, which allows water and nutrients to easily pass through.

There’s usually no perfect mix as varying conditions will affect the type of qualities you need your soil to have. 

Hence, most gardeners often make their own soil by playing around with various ratios of different soil types and amendments.

7. Nutrition Content

Nutrition Content
Image: Neslihan Gunaydin on Unsplash

Regardless of what type of plant you’re growing, you’ll want to use nutrient-rich soil to ensure that it develops properly and healthily. 

This is especially so when growing fruits and vegetables as nutrient deficiencies can result in your plant struggling to fully develop. 

Most outdoor potting mixes have adequate amounts of nutrients listed in their ingredients catalog. Even then, it’s important to do a bit of extra research to ensure that it only has beneficial elements.

The most commonly included nutrients are nitrogen, phosphorus, and potassium (NPK). They often come in larger doses than other important nutrients, specifically – 15% nitrogen, 10% phosphorous, and 8% potassium.

While this is great as it is, there are certain plants that require more than that. They need extra doses of macronutrients and micronutrients for optimal growth.

Here’s a list of macronutrients you’ll want to see in your soil:

  • Calcium
  • Carbon
  • Hydrogen
  • Nitrogen
  • Sulfur
  • Phosphorous
  • Potassium
  • Magnesium
  • Oxygen

These are a couple of micronutrients and trace minerals that can benefit your soil composition:

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

FAQs

How much organic matter should I add to my outdoor soil?

It’s recommended that the ideal amount of organic matter to have in your pot of outdoor soil would be about 3 to 5% of the total soil composition.

How can I add more nutrients to my outdoor soil?

You can easily boost the nutrient content of your outdoor soil by adding organic matter, compost, manure, fertilizer, and mulch.

Can I reuse old soil for new containers?

It’s not recommended to reuse old soil as it could contain various contaminants such as diseases, bacteria and bugs. These can unknowingly infect your new plants, or worse, spread across your garden.
Aside from that, old soil is often depleted of any nutrients as its previous inhabitants have most likely already absorbed them all. Hence, your new plant may not have any left to take in.

What’s the ideal pH level for outdoor soil?

The optimal pH level for outdoor soil should be around 6.0 and 7.0, which is relatively neutral but slightly acidic. 
However, the best pH level for your soil will also depend on what type of plant you intend to grow. For example, several acidic soil-loving plants include:

VegetablesFruitsTreesFlowering Plants
Sweet cornCranberriesBeechAzaleas
CucumbersHuckleberriesWillowTrifolium ruben
BroccoliBlueberriesOakBegonias
TurnipCranberriesDogwoodAsian bleeding-heart
OnionLingonberriesMagnoliaDaffodils
SquashBilberriesPineCamellias

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