If you’ve got unfinished compost, you may be wondering if it is safe to use on your garden or if this is not ideal.
Will it work as a good soil amendment and improvement, or should you hold off until it is completely finished decomposing?
Unfinished compost is perfectly safe to use in certain situations, but it should not be used for seedlings or plants that don’t prefer low nitrogen levels.
If you want to mulch your ground or enrich it below the surface, unfinished compost can be a perfect way to do this.
How Do I Know If My Compost Is Unfinished?
You will easily spot the difference between unfinished compost and finished compost just by the appearance.
Depending on what you have put in your compost, you will likely see some leftover tougher material in the unfinished compost.
For example, you might see bits of twigs, eggshells, fruit peels, pieces of straw, and the woody ends of vegetables among the browner material that has composted.
The softer materials like tea leaves, vegetables, fruits, and green materials will likely be completely gone.
You may have also noticed that unfinished compost is warm while finished compost is much cooler. This happens because the unfinished compost is still decomposing and the bacteria that are breaking down your compost are generating heat.
Why Does Unfinished Compost Affect Nitrogen Levels?
While it’s safe to add unfinished compost to your existing soil if it has been incorporated into your garden beds, it’s important to understand how it can impact your nitrogen levels.
Unfinished compost affects the nitrogen in your existing soil, because as the compost breaks down, it will “borrow” nitrogen from the surrounding soil.
Too much carbon in the compost will mean that more nitrogen is pulled from the surrounding soil in an attempt to balance the carbon/nitrogen ratio.
Most of the carbon left when the compost is finished will contain well-decomposed plant residue. So, whatever was originally food waste, grass, or other nitrogen-rich ingredients will have broken down leaving mostly carbon.
It will take time for nitrogen levels to equalize, however, until that happens, it can be detrimental to plants needing an immediate source of nitrogen that is not bound in compost.
What not to do: Don’t place unfinished compost around the base of a plant needing high nitrogen levels, or you may have to apply nitrogen fertilizers to help maintain healthy growth.
What Can I Do with Unfinished Compost?
If you have compost that you would like to use up for some reason and it is partially composted (or unfinished), you can always do one of the following two things:
You can either use it as mulch, or you can till it down into the ground in the winter.
Using It as Mulch
You can spread unfinished compost around your plants as a mulch forming a thicker mound for holding moisture within the soil over the summer. This works well around larger plants, especially large bushes and trees.
You don’t want to mix unfinished compost into your normal soil in areas where you want to grow plants soon, or where other plants are already growing.
You can do this with more of a chance of success if you add another nitrogen source or if the plants are very rugged. Your safest bet is to only use it as a mulch on top of the soil.
It will prevent the material from having a significant effect on the soil below because it will only share contact with the surface of the soil and will not pull nitrogen from around the roots of your plants.
Over time, the goodness in the compost will leach into the soil, and the unfinished compost will continue to decay and break down into finished compost, which should produce better soil throughout as it leaches and exposes the area under the mulch to the benefits of compost.
It’s up to you: If/when the compost has completely finished, you have the option of incorporating the mulch back into the soil, but you don’t have to. The nutrients will infiltrate and be available to the roots, whether or not it is buried.
Digging It Into the Soil
If you have an area of bare soil with no immediate plans, you can dig up your unfinished compost and place it beneath the ground.
It will do its thing under the soil and build the soil for whatever planting you would like to do down the road. You may have heard of trench composting, which is almost exactly what this is.
To dig your compost into the ground, first dig a hole larger than the amount of compost you would like to bury just as long as it is easy enough to be deep enough to cover it with soil.
Tip the compost in and cover it up well with dirt patting down the top. This will help keep rats, mice, or other curious creatures from taking swims in what you have buried.
If you do not do this your unfinished compost will likely end up dug up and all over your yard.
Good To Check: You just want to be sure to make sure everything has decomposed before you add any plants to the soil. Just dig down and check to make sure all the soil looks brown, and crumbly and then you can be safe to add plants. They should be fine since the compost should have stopped pulling nitrogen from the surrounding soil.
Is Unfinished Compost Ever Bad for Plants?
Indeed, if there is not enough nitrogen in the soil, unfinished compost will lock up the available nitrogen and can be detrimental to plants.
Most plants need nitrogen to thrive, and if insufficient nitrogen is available in the soil, plants will stress out.
If you have already incorporated unfinished compost into the soil around your plants, there is no need to panic.
What to do: You will want to add a nitrogen-rich fertilizer to the soil, and you will not want to add any more finished compost. After some time, you can check the balance of nitrogen using a soil-testing kit (click here to access soil kit instructions).
Summary
Therefore, unfinished compost is pretty benign, but it should not be applied around plants that are actively growing.
If you want to put the unfinished compost to use simply to empty the bin and start fresh, you can either mulch or dig it in.