What is the best soil to use for planting flowers?

What Is the Best Soil to Use for Planting Flowers?

Discover the benefits of the loam soil for flowers.
Learn which plants thrive in specific soil types like sandy, clay, or silt-based soil.
Understand how to amend soil to improve its quality and suitability for different plants.
Find out why garden soil needs to be sterilized for indoor plant use.
Get tips on creating your own custom soil mix for houseplants.

Soil falls into three main types - sand, clay and silt. Generally speaking, the best potting soil for growing flowers is an even mix of the three aforementioned soil types and is called sandy loam. This mix will ensure optimum growth conditions for most flowers. Yes, most flowers, but not all flowers. Depending on the plants you’ll be looking after, you might need to go for a particular type of soil. So, let’s take a look at the different types of soil and which plants grow best in which.

Types of soils and when to use them

Soil texture normally depends on the amount of silt, sand and clay it contains. That being said, the quality of nutrients and drainage properties of the soil will depend a lot on its texture.

Loam Soil

Loam soil consists of a well-balanced mix of sand, silt, clay and humus. The reasons this soil is so often used for growing plants are the following:

Advantages of loam soil

It contains high calcium levels - Calcium is good for stimulating healthy plant growth. It helps maintain the balance of soil chemicals and ensures that water reaches the flowers’ roots by improving the soil’s water-retaining ability. Calcium also helps loosen the soil and this way, facilitating oxygen to reach the plant’s roots. Calcium is great for reducing the amount of salt found in the soil. Which is great, considering that too much salt can damage a plant’s root system and limit its ability to absorb all of the much needed nutrients.
It has higher pH levels - Most plants prefer pH levels between 6.0 and 7.0. The plant’s ability to grow is greatly influenced by the soil’s pH level. Since loam soil’s acidity is within the favorable range, it allows for good plant nutrients and other soil organisms, such as earthworms, to thrive in it.
Has a gritty texture - Loam soil is dry and soft but has a nice gritty texture, which causes it to crumble easily. This type of texture helps increase its amazing draining properties, while also retaining water and plant nutrients. So, plants have consistent moisture and food. And since loam soil is crumbly, this also allows for air to easily flow through it all the way down to the roots.

Disadvantages of loam soil

There are instances in which loamy soils contain stones that may affect the harvest of certain crops.

Plants that grow well in loamy soil

Dog’s Tooth Violet
All species of dog’s tooth violet prefer well-drained, loamy soil.
Rubus
This hardy plant prefers full to partial shade and grows best in moist loamy soil.
Wisteria
Wisterias love well-drained, fertile and rich in nutrients and organic matter loamy soil.

Silt Soil

Silt-based soil is composed of intermediate sized particles and can be a bit tricky to work with. Since there’s a risk of it compacting when wet, you will need to increase its organic matter by mixing it in with compost and other soil microbe-rich products. Here are some of the advantages and disadvantages of using silt soil in your garden:

Advantages of silty soil

Silt is very fertile and holds on to nutrients very well
Has good water holding capacity

Disadvantages of silty soil

Water filtration of silty soils is usually poor
Can become hard and compact
Silt soils often form a crust

Plants that grow well in silty soil

Yellow Iris
An adaptive flower, which is often grown around a garden pond or stream.
Swamp Milkweed
A flower, which thrives in soggy soil.
Japanese Iris
A flower that loves water and is best planted around a water feature or wet area inside your garden.

Sandy Soil

Sand is the most prevalent part of this type of soil and its consistency is light and gritty to the touch. Sandy soil doesn’t have many benefits and can be used to grow only a few types of plants. However there are ways to make it more manageable. For example you can amend sandy soil with fewer fertilizers and small amounts of water but on a more regular basis. Its organic matter can be improved by adding compost to the mix.

Advantages of sandy soil

Warms up quickly during spring

Disadvantages of sandy soil

Dries out very quickly during summer
Any nutrients you do put in it are oftentimes washed away during rainfall

Plants that grow well in sandy soil

Butterfly Weed
This butterfly magnet of a plant loves full sun exposure and prefers well-draining, dry sand-based soil.
Adam's Needle
This plant loves dry sandy soil and hates damp soils, which cause its roots to rot. Also, Adam's Needle can tolerate salt spray, which is said to decrease blooming and enhance the plant's green colour.
Blanket Flower
This drought-tolerant plant thrives best in sandy, almost pH-neutral soil.
Wormwood
A perennial herb, which is drought-resistant and grows particularly well in less fertile, dry sandy soil.

Clay Soil

Clay soil contains copious amounts of clay and due to that, it drains very poorly. However, with the right management techniques you can improve its overall quality. Simply amend your clay soil with compost and products rich in soil microbes in order to improve its organic matter. Also, try not to work on the soil while it’s still wet.

Advantages of clay soil

Clay soils are good at holding onto nutrients
This type of soil is amazing for growing plants which require copious amounts of water

Disadvantages of clay soil

Drains very slowly
Warms up slowly during spring
Compacts easily
Is often too alkaline

Plants that grow well in clay soil

Black-eyed Susan
This plant can survive in both loamy and clayey soils, but does need proper drainage.
Bee Balm
There are varieties of Bee Balm that prefer sandy soils and others that grow better in loamy or clayey types of soil.
Goldenrod
A very adaptable flower that can survive in pretty much any soil, even clay.

How to grow indoor plants with soil from your garden?

When it comes to growing houseplants, avoid scooping soil directly from your back garden. Since garden soil contains many different types of bacteria, this can be harmful for your houseplants.

However, if you’re really keen on growing your houseplants in soil from your garden, make sure to sterilise it, first. Pasteurising outdoor soil will help you eliminate any disease, weeds or pest insects from it. The process itself is quite easy, simply spread your soil on a baking sheet, place it in the oven and bake for around 30 minutes at 180 °C. Just bear in mind that this method, although effective, will leave a foul odour in your kitchen once done.

Once the soil has been sterilised, you’ll have to amend it with the necessary amount of sand and peat moss. Adding these to the mix will help improve your soil’s drainage, air flow and moisture-retaining properties.

How to mix a batch of amazing soil for houseplants at home

Outdoor soil aside, another way to get great soil for your houseplants is to make your own mix. For this, you will need to buy a few different types of soil and soil amendments. In order to get the best quality soil, buy and mix the following:

Half a cubic yard of yard perlite
Half a cubic yard of peat moss
Ten pounds of bone meal
Five pounds of limestone
Five pound sof blood meal

Once you mix all five of these, store the finished product in a proper airtight container. Open it only when you need to use the soil.

What to look out for when buying or making soil

When mixing or buying soil for your back garden or houseplants, it’s always important to follow certain guidelines. By that we mean - make sure that the soil you’ll be using isn’t contaminated. Also, beware that sometimes store-bought soil may contain weed seeds, which you don’t want, of course.

Watch out for large stones and debris

Things like plant roots, stones, decaying wood or manmade rubbish should definitely not be part of your soil mix. These can block your flowers’ root-run and cause drainage problems. Buying soil is pretty much the same thing as mixing it - always inspect what you’re getting. You don’t want any rocks as part of your soil mix, so opt for some good ol’ screened soil from a reputable supplier.

Screened soil is soil that has passed through a giant sieve, in order for any large particles to get filtered away. If your soil supplier tells you that their soil has gone through 20mm screening, this means that nothing with a diameter bigger than 2 cm has passed through the sieve.

Never buy soil that has been chemically contaminated

If you’re planning on mixing your own soil at home, you don’t really need to worry about your soil being chemically contaminated, unless you dumped some chemicals on it yourself. However, when buying your soil from a retailer, always ask them for a certificate, which proves that their soil has been tested for chemical contaminants. Because even though, sometimes, these can be sniffed out, most of the time, they blend in with the smell of the soil.

So, to sum up, learn what the plants you want to have prefer as a growing medium. Always, make sure to use reputable soil suppliers, when you need to buy some soil. And last but not least, don’t be afraid to make your own potting mix, as this will ensure that you get the best type of soil for your particular plants you’d like to grow.

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