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Is 50:50 Soil Good Enough for Raised Garden Beds?

Is 50:50 Soil Good Enough for Raised Garden Beds?

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Once the structure of your raised beds is ready, the next step you should take is to fill them with soil and get them ready for planting. However, before adding soil, you need to determine what type of soil you should add and what the ratio of topsoil to compost should be. 50/50 soil is one of the most popular options on the market – but is it good for raised beds?

50/50 soil is good for raised beds. This blend is very popular in gardens in the United States and ensures your plants are healthy and have enough nutrients. However, some people find adding 50% compost to be expensive. If so, you can change the ratio – anything from 70/30 to 95/5 mixes are okay.

Keep reading to get more information about what soil you should add to your raised beds and what soil ratios mean. I’ll cover everything you need to know about choosing the right soil for your raised beds so you can move on to planting seeds.

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Understanding 50/50 Soil Mix

50/50 soil mix is essentially a soil mix that contains 50% screened topsoil and 50% compost. Some soil mixes will include other organic matter instead of just compost, making the composition 50% topsoil and 50% organic matter. 

This soil mix is designed to ensure that your plants have enough nutrients and that you do not need to add more organic matter to the soil anytime soon. 

Depending on how much organic material they want to include in their soil, some people will also fill their garden beds (both raised and traditional) about ¾ of the way with 50/50 soil and then add an additional compost layer for the last ¼.

Some people make their own compost, while others buy compost in bulk and mix their own 50/50 soil. Alternatively, you can purchase pre-mixed 50/50 soil. 

The main challenge with 50/50 soil is that if you’re mixing your own and using commercial compost, it can be expensive. This is why many people prefer using a mix with less compost, especially if they have numerous raised garden beds to fill.

What Is Screened Topsoil?

As mentioned above, 50/50 soil mixes (and other types of soil mix) use screened topsoil as one of their components. 

Screened topsoil is topsoil that has been filtered to get rid of any debris that may hamper the growth of plant roots. This includes rocks, soil clumps, and sticks.

You can screen topsoil at home. All you need is topsoil from your garden or backyard and a mesh soil sifter. Keep in mind that topsoil is unamended soil. If you have previously enriched your garden soil, it will not count as topsoil.

Once you have your topsoil and sifter, the next step is to run the soil through the sifter. By selecting the screen size, you can choose how fine you want your screened topsoil to be. A standard option is to opt for a ½ inch (1.27 cm) mesh, but you may prefer soil that is either finer or coarser.

After you run the soil through the sifter, the soil that passes through is your screened topsoil. 

Unscreened topsoil is often used to build the base of garden beds, and you can place your soil mix over it. It is also used for construction projects, such as filling in holes in your lawn or leveling slopes in your backyard.

However, if you don’t have space to store the unscreened topsoil and don’t anticipate using it soon, you are also free to throw it away.

To get a better understanding of how to use a soil sifter to screen your topsoil, take a look at this YouTube video:

DIY Soil Sifter // GREAT for Lawn Leveling

It also gives you instructions to build a DIY sifter if you’re looking for a bigger option than is commercially available.

The Best Soil for Your Raised Garden Beds

Numerous factors determine the right soil mix for your raised garden beds, including your budget. However, among the most important considerations is what plants you plant to grow in the raised beds. 

Different plants need different types of soil. 

For example, vegetables grow best in loam soil. This soil is an equal mix of sandy soil, clay soil, and silt (source).

However, soil without organic matter is not conducive to plant growth. Additionally, loam soil cannot be created by simply “stirring” the abovementioned soils together.

Instead, to make fertile loam for your raised beds, you will need to incorporate organic matter such as compost, leaves, and straw to ensure your loam is both nutritious and conducive to the growth of plant roots.  

On the other hand, flowers like blue hydrangeas need acidic soil to grow in. This means you’ll need to include acidifiers into the soil to ensure these flowers grow properly, which will affect your soil mix (source).

Ultimately, matching your plants to your soil mix is essential to get the most out of your raised garden beds.

How Much Soil You Need for Your Raised Bed

As mentioned above, one concern people have about using a 50/50 soil mix for their garden is the cost. However, if you’re just getting started with raised bed gardening, you may wonder how this works – after all, isn’t the cost of soil relatively affordable?

Many people don’t realize just how much soil is required for gardening, especially raised bed gardening. 

To figure out how much soil you need for a rectangular or square bed, you should multiply the dimensions of each bed. That means you will be multiplying the length, width, and height of each bed together. The resultant number is the volume of soil needed for your raised bed (source).

So, if your bed is 6 feet (1.83 m) long, 4 feet (1.22 m) wide, and 1.5 feet (0.48 m) high, you would get a volume of 36 cubic feet (1.02 cubic meters). 

Generally, soil is sold by the cubic yard. If you’re starting with a number in cubic feet and need to determine how many cubic yards of soil you need, divide the number of cubic feet by 27. So, for a volume of 36 cubic feet (1.02 cubic meters), divide by 27, which gives you 1.3 cubic yards (1.02 cubic meters). 

And this is only for a single raised bed. If you’ve got multiple beds, the cost adds up quickly. 

Even if only buying compost and not a blended soil mix, the costs can be prohibitive for many people. This is why many people prefer to create their own blends using topsoil from their garden and adding easily available organic matter such as leaves – or making their own compost with kitchen scraps.

Final Thoughts

50/50 soil mix is a good option for raised garden beds, but it is not the only available option. If you prefer an alternative with less compost to keep costs down, you can also use 70/30 soil or lower – as far down to 95/5 soil. 

You should always match the soil you use with the plants you plan to grow. This may require tweaks to the ratio of your preferred soil mix or the inclusion of specific soil amendments to create the ideal soil conditions.

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Willie Moore
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