What Is The Best Ratio Of Compost? 6 Most Common Ratios

Organic fertilizers are adequate nutrients for plants. Yet, using them is not easy. What is the best ratio of compost to soil? There is no one perfect. Depending on the type of tree you are growing, the balance will vary.

Whether you mix fertilizers in the ground or spread them on top, they will provide nutrients effectively. You need to learn about the correct mixing ratio in the article below.

Types Of Compost

There are several types of organic fertilizers that you can use to add nutrients to the soil. You can choose the most appropriate variety in the following.

Homemade fertilizer - What Is The Best Ratio Of Compost To Soil

Homemade fertilizer

Homemade Compost

People make this type of manure from garden and kitchen waste – nitrogen and carbon.

Making this organic fertilizer is relatively easy. You’ll also benefit from composting the wormwood in the process.

Mushroom Compost

The composition of this fertilizer is the spent organic nutrients of the mushroom producers.

This organic nutrient is a slow-release fertilizer. However, its nutritional effect is excellent.

Peat Moss

Peat moss is suitable for acid-loving plants such as blueberries and rhododendrons. The main components of the mulch are acidic leaves, such as oak leaves and pine needles.

Before use, you should measure the pH to check and evaluate the concentration of the ground.

Composted Manure

Many people also use well-rotted manure from livestock waste such as chickens, cows, and horses. It requires to be free of weeds and to be thoroughly rotted.

Green Manure

Last but not least, we have green manure through planting cover crops. Its primary purpose is to increase the humus content of the garden soil.

You will cut the plants and spread them in the top layer of ground to let them decompose. Another way is to dig them deep in the ground.

What Is The Best Ratio Of Compost To Garden Soil?

Let’s find out the proportions of organic fertilizer and ground corresponding to different plants below.

Raised bed gardens - What Is The Best Ratio Of Compost To Soil

Raised bed gardens

Raised Bed Gardens

You should improve the ground to increase nutrients in raised garden beds. Make sure the finished fertilizer does not include weed seeds.

The most common mix is ​​30% finished compost with 60% potting soil. For the rest, you can add perlite or vermiculite.

After the first growing season, you can add about 1 inch (2.5 cm) of nutrients to the top. Since the composting process will continue, you do not need to select the finished compost.

Potted Plants

Potted plants tend to drain and dry quickly. So, the best soil mix ratio will range from 20 to 50%.

The higher the soil mix ratio, the lower the ground drying rate and the longer it helps retain moisture.

If you use a clay pot, add more compost to the healthy soil. The reason is that this type of pot drains very quickly.

Allow nutrients to settle into the disturbed soil for two weeks after tilling. Digging into loam soil is not required.

Flower Gardens

Compost mixture for flower soil will have a ratio of about 20%. In it, you’ll mix one-part fertilizer with four parts dust.

The maximum amount of compost to use in ground soil for flower beds is 30%.

To increase nutrients, you can also apply ¼ to ½ inch of fertilizer over perennial flower beds.

Vegetable Beds

For ground soil used for growing vegetable gardens, the maximum rate of organic fertilizer is 30%.

If you’re mixing using a shovel, aim to add ⅕ inch of compost for every inch of soil as measured by the shovel. Measure the length of the shovel blade and calculate the appropriate proportions.

You can spread about an inch of the nutrient over the surface for those using a mixer. Then, mix it about five inches deep into the ground.

More to read: How To Store Compost Properly? Get Your Job Done With 9 Tips


When you add organic nutrients to your lawn, the microorganisms are nourished to make the soil more fertile. As a result, the grass is always greener, and the spread of weeds is limited.

A compost-to-ground ratio for new lawns is one to two inches of nutrients and tilled evenly into the top six inches of soil. Then scratch the surface and sow the seeds.

If you want to restore existing lawns, cover with ⅛ to ¼ inch of nutrients. You can also lightly rake the ground before spreading it for the best results.

More to read: How To Amend Clay Soil Without Tilling? 6 Essential Steps

Trees And Shrubbery

Large shrubs and trees will need a compost ratio of about 10%. You’ll need to mix one-part fertilizer with nine parts soil.

Perennial plants do not need too many nutrients to grow. You only need to top-dress from ¼ to ½ inch to the tree’s drip line, the area that the canopy covers.

How To Add Compost To Soil?

Returning nutrients to the earth - What Is The Best Ratio Of Compost To Soil

Returning nutrients to the earth

The first thing to notice is that your compost is wholly rotted and free of weeds.

Many people believe that mixing nutrients into the soil will break down mycorrhizal fungi and increase the plant’s ability to absorb them.

However, this mixing method is quite suitable for sandy or clay soils. The reason is that it strengthens the ground structure to prevent disruption.

If the texture of the ground is already solid, you can spread the fertilizer on the surface. Over time, rain, insects, and natural agents will mix them deep inside.

You can watch more videos below to understand the process and the tools needed to mix fertilizer into the ground.


Gardening is a vast field, and there is still a lot that you may not know. Read on below to learn more about fertilizing your ground.

FAQs about compost - What Is The Best Ratio Of Compost To Soil

FAQs about compost

How Much Compost Do You Mix With Soil?

The ratio formula for mixing fertilizer with potting soil is quite simple.

You should mix ½ to ¼ inch for the top layer and mix 1 to 2 inches into a 6 to 8-inch thick potting soil.

When converted to ratios, the maximum recommended percentage of fertilizer ranges from 25-30% in the ground mix. For containers or raised beds, this ratio should not exceed 25%.

Can You Add Too Much Compost To Ground?

Compost has the effect of improving fertility and increasing organic matter in the soil. However, if you over-fertilize, it will negatively affect plant health and the environment.

Too much compost will cause phosphorus poisoning for green plants. This problem is quite common because many products have not been wholly decomposed on the market.

Does Compost Need To Be Mixed With Soil?

Some experts recommend that you spread the compost over the ground instead of mixing it deep inside.

Digging compost for fertilizer will disturb the position of delicate mycorrhizal fungi, which interfere with the absorption of nutrients by the plants.

Can You Plant Directly In Compost?

While this idea sounds appealing, you shouldn’t plant plants directly in fertilizer. The reason is that the material is too light and drains too quickly.

This nutrient’s fragile texture will cause the tree to fall because it does not support the roots well. In addition, it also causes phosphorus poisoning.


What is the ideal compost to soil ratio? There is no one correct answer to this question as each crop and ground will require a different balance.

As you get more experienced in gardening, the blending will become gentle. You will derive the most suitable formula for your garden in the long run.

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