A Guide to Re-Using Soil

As the radiant days of summer comes to an end and winter starts grasping everything in its reach, we find the flower beds and pots, once brimming with life, now filled with lifeless vegetation. This is a natural cycle, and there’s no way around it. This is the reason behind the great loss.

However, if we’re concerned about it, we can reduce the losses to a great extent. If you’re looking at your dead flowers and thinking that you’re going to dump them very soon, stop right there. Dumping the flowers won’t do you any good. On the other hand, you can use these dead plants to minimize the loss to a great extent by re-using the soil. 

In this guide, we tried to cover everything there is to know about re-using soil and more! Stay with us till the very end, and hopefully, you won’t have to resort to any other source!

plants in pots
Plants in Soil Pots

How Can You Minimize Waste?

If you’re a gardener, probably you know how expensive soil can be. Although it might seem that soil is present in our environment is abundant, and we can get soil without paying a penny, the reality is quite the opposite. 

Although soil is present in abundance, quality soil necessary for growing plants is still rare. That’s why, each year, gardeners have to spend a lot of money on acquiring suitable soil for their plants. 

This is where many people ask, “Can I re-use soil from a dead plant?” Yes, you can. However, it takes great skill and in-depth knowledge of the soil type to understand how to re-use the soil. That’s why, before we get to how you can re-use soil, we’re going to talk about the very composition of the soil. Here it is:

Ideal Soil Composition

If you buy a mix or a growing medium for your plants, you’ll find three components in it. These are:

Material like Peat Moss

What is peat moss? You might ask. Peat moss is essentially a dead, fibrous material, and it’s created when different living materials and mosses are decomposed together. The main difference between common compost and peat moss is that the main component of peat moss is moss, and another major difference is that peat moss takes a long time to be produced. 

How long does it take to produce peat moss?

Well, about several millennia only! Unlike compost, peat moss decomposes in the presence of air, which slows the process down to a great extent. This makes peat moss very rare, hence the high pricing of sterile growing mediums. 

Peat moss is a very important component of good soil, as it’s very light. Unlike the soil collected from your yard, the sterile growing mediums aren’t full of clay or sand. 

However, there are a lot of brands that offer coir instead of peat moss. Unlike peat moss, coir can be extracted very easily from coconut. Essentially, coir is a type of fibrous material that can be extracted from the outer and inner shells of coconut. 

In fact, coir is even better than peat moss in some factors. For example, the water retention capacity of coir is much higher in coir than peat moss. Then again, it re-saturates faster too. Plus, coir is not only organic, but it’s great for growing crops, and the best thing about it is, it’s renewable. 

However, all the good talk about coir doesn’t mean that it’s completely free of flaws. Due to the high-water retention capacity, we can see a higher level of salt buildup in coir, which can be detrimental for some plants.  Then again, although coir can be extracted more easily, it’s more expensive than peat moss. 

Even then, coir is more favored by the farmers, horticulturists, and gardeners. 

Soil Nutrients

There are two ways of adding essential nutrients to the soil. The more cost-efficient and used method or the traditional method is worm castings, which is also known as vermiculture. When earthworms intake organic matters, the components get changed when they’re moving through the bowels of the worms, and they’re excreted in a completely different state. 

The product excreted by the worms is full of essential nutrients and bacteria that help plants grow fast. These nutrients and plants remain ready at the plant’s roots, which makes the nutrition intake of the plants much easier. 

Other than adding nutrients only, the worm castings also maintain the pH of the soil, add heavy metals to the soil, filter the harmful chemicals out of the soil, increase the moisture retention of the soil. Worm castings can be purchased, or they can be produced easily.  

The other thing that can help you add soil nutrients is perlite. These are white, puffy granules that can be bought as a starter mix. These granules are essential nutrients exposed to high heat.

How to Create Vermicompost?

Here, we’ll add a short step by step guide on how you can harvest worm castings on your own! If you follow this guide, you’ll be able to save up on a lot of money! 

  • Step 1: At first, you need to get yourself a vermicomposter. A vermicomposter can be made, or it can be purchased from a local shop. If you’re good at making things on your own, you can create a vermicomposter on your own very easily.
  • Step 2: You don’t want to put your vermicomposter in a place with a lot of rain and wind. Try to put it in the shade or putting it under a tree will also work. 
  • Step 3: Before you put in the organic materials, you must create a bed. The bed should be around 3 inches deep, and you can use either peat moss or coir. Whether you’ll be using peat moss or coir as the bed is completely up to you. Personally, I like using coir. 
  • Step 4: Not every worm can provide the same result. Usually, farmers prefer using Eisenia Foetida, or Californian redworms, as these are one of the most voracious worms out there. These worms can create a huge amount of castings in a very short time, which makes them the most suitable. Once you get the worm of your choice, you need to put them on the bed. Then, cover the container and let them get comfortable for a day. 
  • Step 5: After a day, you can start adding in the organic materials. You can start by adding dry leaves at first. Increase the number of organic materials with time, and always cover them with a top layer of the same material used to create the bed. You can use organic materials like vegetables, fruit peels, dry leaves, eggshells, and coffee grinds. However, using meat, cooked, or oily food is a very bad idea. If you do this right, the liquid excreted by the worms will start collecting at the base of the container. 
  • Step 6: Now, it’s time for you to wait. It usually takes from six to eight weeks, and the time depends largely on the number of worms you’re using. The excretions of the worms, the dark, soil-like materials that’ll collect at the bottom of the container are the worm castings. These will be your fertilizer, so you should take care not to spoil even a bit of them. 
  • Step 7: The last step is harvesting. You can collect the castings easily if you put a tray below the container. If you find a lot of worms once you open the container, you can put it under direct sunlight, which will force the worms to retreat to the bottom. You’ll understand whether it’s the right time to collect the feces if you find that all the materials in the container have turned into homogenous soil like component. If you find some worms in your vermicompost, you need not worry, as the worms won’t harm your plants. 

Now, you may think that the process of collecting coir, worms, and organic matters will get very costly over time, but the reality is the opposite. If you take good care of the ants, they’ll reproduce in number, and you’ll be able to use them again and again. This will reduce your expenses to a great deal over time. 

However, you should keep the container free from insects at all costs. To save the container from flies, always cover the top layer with the same material as the bed. Then again, if you find ants in the container, it usually means that the organic matters have become dry. To prevent this, you should dampen the organic matter a bit, and you’ll find everything okay.


Compost is the third ingredient we’re going to talk about. Now, compost can be produced by the gardeners, or it can be bought in a pack. Gardeners and farmers usually make their own compost using eggshells, dry leaves, or leftover vegetable peels. The more carbon-rich components are added, the better the compost becomes.

If you want to create the perfect compost for your garden plants, you need four things. These are:

  1. Right organic materials
  2. Air
  3. Moisture
  4. Time

If you lack even one thing out of these four, we recommend you buy ready compost from a local store or from Amazon. There are lots of sellers that are selling top of the rack composts at a very decent rate, and it makes the whole process much easier. 

However, if you want to be self-sufficient, you can create compost by yourself. The choice is completely yours. 

Now that you know the essential components of an ideal soil for growing plants, we’re going to talk about how you can re-use your potting soil for another season. So, let’s get started! 

How to Re-Use Potting Soil?

To be honest, a lot of complications may arise when you’re thinking, “Can I re-use soil?”, and we’ll talk about these later in this article. However, we assure you that if you follow the methods we explain, you won’t suffer from any of these. 

In fact, if you can make a habit out of re-using potting soil, you can reduce your expenses to a great extent in the long run. This is especially true if you have a lot of pots in your garden, as it’ll eliminate the entire cost of buying new potting soil. 

However, to re-use your potting soil, there’s a lengthy process that you need to follow, and this process begins at the very end of the growing season. At the end of a growing season, most gardeners clean out the organic matter from their garden, and it’s the same when it comes to pots. 

At the end of the growing season, you should sift through the potting soils. This will provide you the opportunity of getting rid of any insect, weed, or unnecessary material. Plus, you can also clean your pots so you can get rid of the fungus, viruses, and bacteria that have accumulated on them throughout the entire season. 

However, to get rid of the bacteria, you need to use organic soaps that are plant-friendly. If you use chemical soaps, the compounds may hinder the growth of your plants. If you want, you can also wash them with only water, but this will not get rid of the fungus, bacteria, or virus. 

Now that you’ve cleaned the pots, you need to clear the soil completely. To start, you can sift through the soil to find out if there’s any larva egg, weed seed, or pathogens in the soil. If you find these, you should get rid of them immediately. Otherwise, you’ll suffer from an infestation in the next growing season. 

If you find it tough to go through and clear the soil, you can follow another technique. You can literally bake them in the sun, and here’s how to do it:

  • At first, put all the soil in black colored bags or containers. 
  • Then, keep them under the sun for a long period of time for a few days. As they’re dark containers, the entire heat of the sun rays will get trapped inside them and will roast the soil.
  • This immense heat will destroy any weed seed, pathogen, or larva egg in the soil. 

If you find it tough to go through the soil manually, this method is for you. It can save a lot of your time, and it’ll reduce your efforts as well! However, we highly recommend you go through the soil manually as well, just to be sure. 

We recommend this because, no matter how careful you are, there’s always a chance that the next time you grow crops, you’ll find some issues. However, there are some other methods that you can follow to reduce these changes to the greatest extent. 

If you want to make sure that all the weed seeds, larva eggs, and pathogens of the potting soil are destroyed, you can pasteurize the soil. However, I’d like to add something at the very beginning, and that is, pasteurization is available to commercial gardeners and farmers only because it involves a lot of advanced equipment. 

In the process of pasteurization, the soil has to be kept at a temperature of 180 degrees. This must be maintained for thirty minutes, and once the soil reaches 212 Fahrenheit, all the larva eggs, weed seeds, and pathogens will get killed effectively. 

However, passionate horticulturists have found a way around this. If you don’t have access to the advanced heating gears, you can use your oven! If you heat a soil cake in your oven for thirty minutes, all the weed seeds, larva eggs, and pathogens will get destroyed. 

Although this is accessible to almost everyone, there are certain cons to this process. Firstly, as the ovens aren’t much big, you’ll have to spend a lot of time creating smaller chunks of soil cakes from the heap of your garden, and you need to heat them up individually to clean them up. Then again, all these heating will leave an earthy smell in your oven, which isn’t pleasant at all. 

Even if we assume that you’re going to buy a separate oven for this task alone, it reduces the feasibility of this option. Then again, you’ll still have to heat small cakes of potting soil individually, which will be a very time-consuming process. 

If you know that the previous batch of plants had pathogen, and if you don’t have access to pasteurization, then you shouldn’t use that potting soil at all. This will only ensure that the next batch of plants ends up with pathogens as well. 

Remember, the target is to reduce costs. If any of the insects, weeds, or pathogens get transmitted to the next batch of plants, you’ll only suffer from a huge loss. 

Preparing the Next Batch of Potting Soil

No matter how well you preserve the potting soil, it still won’t be prepared for planting the next batch of plants until you add the necessary nutrients. Now, we’ll briefly discuss how you can add the essential nutrients to the potting soil after you’ve cleaned the soil and destroyed the larva eggs, weed seeds, and pathogens. 

What Should You Add to the Potting Soil to Prepare it?

Although you preserved the potting soil from the last season, it’s necessary to add new potting soil to the existing one to bring it back to its former self. To do so, you need to add coir or peat moss, whatever was used the previous season, and the amount added should be one-third of the existing soil. 

Then, you must add compost to the mix. You must add compost equivalent to one-fourth soil mass of the existing soil. If you find that the soil is getting a bit heavy and the water retention is too low, you can add some perlite or coir to make it a bit lighter. 

Planting the New Batch

Once you’re done with all of these processes, the soil is finally ready for planting new plants. By this time, you should be done with clearing the insects, weed, or pathogens from the potting soil. Even if you take the most drastic solutions, there’s always a chance that some will remain. So, we highly recommend you pasteurize the soil. 

However, even after that, weed may still grow on the soil. To prevent this from happening, you can put a layer of compost and dry leaves on top of the primary potting soil layer. This will keep sunlight from reaching the soil, which will keep weed from growing. 

Potential Risks of Re-Using Soil

Even if you can manage to create a great mix, you might not be able to get a great result out of them. If you follow the methods we talked about earlier, you won’t face any issue. However, if you don’t, this is what you can expect:

Existing Roots

If you don’t sift through the soil after a growing season, there’s a big chance that the soil will have a lot of roots left from the previous plants. Now, organic materials are great as they can turn into compost gradually. Plus, many of them increase the water retention of the soil. Roots do none of them. 

This means roots only take a huge space in the potting soil, but they don’t provide any benefit. So, you should get rid of the roots after a growing season. This can be done easily by sifting through the soil.

Depleted Nutrients

Plants depend largely on water and the nutrients present in the soil. However, if the soil doesn’t have any nutrients, new plants won’t grow properly. So, it’s necessary to maintain soil nutrients when you’re re-using potting soil. 

Then again, different plants consume nutrients in different amounts. For example, flowers consume potassium more, and tomatoes consume phosphorus more. If you cultivate flowers on a certain soil for a season, it’s very likely that the potassium of that soil has depleted. So, if flowers are planted on that soil for the second season as well, they’ll get stunted, as there will be an acute deficiency of potassium. 


It’s often seen that weed seeds stay deep under the potting soil, and the future batches of plants are harmed due to high weed growth. Even if the weed seeds weren’t there from the beginning, new seeds could always come through wind, insects, or birds. 

So, before re-using the soil, one should be extra careful about the weed seeds. Weed seeds can be taken care of manually by sifting through the soil. However, this leaves remaining weed seeds. If you pasteurize the soil properly, you’ll be able to get rid of the seeds completely.


Another thing that you don’t want is a bunch of nematodes crawling through the potting soil. Not only will these creep you out, but they will also harm your plants. If there was any insect infestation in the last batch of plants, it’s highly likely that there will be more in the new batch as well, unless you get rid of them. 

As we discussed earlier, you can get rid of the larva eggs by sifting through the soil, but that isn’t very efficient. You can bake the soil in the sun to destroy most of the larva seeds. If you want to destroy them completely, you need to pasteurize the soil. 


Pathogens are one of the worst things that you’ll need to deal with. Pathogens are the virus, bacteria, and fungus. Your plants can get contaminated by pathogens very easily, and if they’re kept under the right conditions, they’ll multiply exponentially. 

Pathogens can harm your plants by causing a deficiency of nutrients, different diseases, and finally, death. So, it’s only necessary to take care of the pathogens before planting a new batch of plants. To get rid of the pathogens, you need to pasteurize the soil, and there’s no other way to it. 

What to Do with Dead Plants in Pots?

Sometimes, you can actually make some use out of the dead plants. Here’s what you can do with a dead plant in your pot:

  • If only parts of the plant are dead, you can save the part by cutting those off. 
  • If you see that the roots are alive, you can leave part of the stem to see if you can revive the plant.
  • Repotting the plant can revive the plant sometimes. You can try that out.
  • If your plant is getting too much sun, you can move it to a shade. If it’s not getting too much light, you can move it to a sunny place.

Final Words

Potting soil can be re-used, and doing so will save you a lot of money. However, if you aren’t cautious, you may end up harming the next season of your plants instead. So, we highly recommend you follow each instruction of our guide. If you follow everything we said, you’re more likely to re-use your potting soil for another season without any problem! 

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I've been raised in a family of international gardeners spanning multiple generations, from vegetable growers in Germany to fruit tree growers in Iran. I hope you find the information you read useful to using electric gardening tools in gardening.

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