Is it possible to reuse the soil from a tomato plant?

Jaime BeamerMarch 20, 2023

0 83 10 minutes read

When it comes time to transplant or repot your plants, you may be wondering whether it is safe to reuse the potting soil. Potting soil may be costly; do you have to discard your spent potting soil? Or can you safely reuse potting soil?

Learn how to properly reuse potting soil, how to recharge potting soil, and how to reuse potting soil in this tutorial.

There are pink bars on top and bottom of the image. On the right tis square picture of a woman's hands using a trowel to place potting soil in a basket. On the left is the text "Can you reuse potting soil?"

Contents

Is it okay to reuse potting soil?

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Yes, it’s okay to reuse potting soil. ..as long as you are careful and take steps to correctly store your potting soil and replenish it for next season. If this seems like a lot of effort, see the section below for non-revitalized alternatives to utilize old potting soil.

When recycling potting soil, there are three major issues to consider:

Depleted nutrients
Compacted, compressed soil
Potential for disease

Depleted potting soil

Plants pull nutrients from the soil as they grow. Plants use varying amounts of nutrients and are frequently referred to as either “heavy feeders” or “light feeders.” (There are also medium feeders, which fall somewhere in the middle.)

As the name implies, heavy feeders pull more nutrients from the soil than light feeders. Soil-building plants include peas, soybeans, and clover.

Heavy feeders Use well-known veggies such as tomatoes, spinach, peppers, and zucchini. Your potting soil is definitely exhausted if you’ve cultivated these popular container veggies. Most herbs, carrots, kale, and radish are light feeders.

It’s best to practice soil rotation and plant heavy feeders in fresh soil, medium feeders in soil the next year, and, finally, light feeders. When storing potting soil from heavy feeders and tomatoes, keep it in separate, labeled containers.

It’s essential to replace potting soil with nutrients if you wish to reuse it. Further advice on how to refresh your potting soil may be found in the section below.

Compacted potting soil

Is your pot’s soil level several inches lower at the conclusion of the season?

Instead of being light and airy, potting soil typically gets compacted. This is partially due to the rapid decomposition of peat moss, a common component of most potting soils in the United States. Pine bark, another frequent potting mix ingredient, decomposes fast as well.

Plants cannot establish healthy roots when potting soil gets compacted, and water may pool on top and drain poorly. This is due to the absence of pore space in compacted soil. Pore space accounts for about 50% of good soil. It lets water and air to travel around the roots of your plants and encourages roots to grow freely.

You may and should fluff up your potting soil by hand. If the peat moss has deteriorated, this will not be sufficient to recover your soil. Adding coconut coir (which is what I recommend instead of peat moss) will improve your soil’s structure and water rendition abilities.

Diseased potting soil

If your plants were ill, it is critical that you discard your potting soil and not try to reuse it.

There are a wide variety of plant pathogens and many of them can survive in soil for several years. This is one of the reasons crop rotation is essential.

Tomatoes are prone to an incredible number of diseases and disorders. Several of these diseases have the potential to spread and infect pepper plants.

The bracissa family (crops like broccoli and cabbage) are also susceptible to diseases that can remain in the soil for years. Alternaria leaf spot, for example, has the ability to spread via soil and plant waste.

Do not compost diseased soil. Instead, get rid of it entirely. If you have a worm compost bin, this is the only exemption. Vermicompost, according to Cornell researchers, may decrease plant illnesses in soil.

Pasteurization and solarization of soil may be used to destroy nematodes, weed seeds, and other diseases. Solarization, on the other hand, works better on clay and heavier soils. You can bake soil to kill most pathogens, but this is impractical on a large scale for most people. That is why I advocate just discarding unhealthy dirt.

How to rejuvenate potting soil

I have a step-by-step procedure for recharging your potting soil. Before we begin, it’s crucial to understand why I choose coconut coir over peat moss.

Is peat moss bad?

In the United States, peat moss is very popular among gardeners and commercial producers.

Peat moss is sphagnum moss that has been compressed, submerged under water for many years, and partially decomposed. It grows at a pace of one inch every 15-25 years, making it seem to be a useful renewable resource.

Unfortunately, peat moss degrades quickly. It decomposes after one or two years, and your potting loses its light airiness and becomes dense and difficult for plants to thrive in.

To collect peat moss, fresh moss must be scraped from the bog’s surface. Mining peat moss alters the environment of the bog and has the potential to change history as well. Peat bogs are ideal for conserving antiquities and mummies due to their low-oxygen environment. (For additional information on peat bogs, see Smithsonian Magazine.)

Peat bogs hold around one-third of the world’s soil carbon. Amazingly, peatlands store 100x more carbon that tropical forests! Carbon dioxide is released during the harvesting of peat moss. If the harvested peatlands catch fire, the emissions are amplified. According to the United Nations, peatland fires account for 5% of global anthropogenic carbon immersions.

Instead of adding peat moss or buying new potting soil that contains peat moss, renew your potting soil with coconut coir.

Coconut coir is a sustainable substance that lasts longer in your potting soil than peat moss. Coconut coir is a waste product of the coconut industry made up of coconut husk dust and short fibers. Each year, around 12 million pounds are generated.

Coconut coir is a more sustainable option than peat moss, and it lasts longer, so you’ll have less work to do next year when you replenish your potting soil.

In the instructions below, we’ll go through how to utilize coconut coir to repair your potting soil. .

Step by step guide to rejuvenating potting soil

This step must be completed at least two weeks before the planting season.

Preferably, you should sift through your soil and remove debris before storing it for the winter, but if you haven’t done, do so before washing and adjusting the pH. I’ve included removing debris from the soil as the first step, but you can skip to step #2 if you’ve already removed all the debris from your old potting soil.

Materials needed for soil rejuvenation

A large tarp or piece of plastic sheet
A soil sieve – optional but recommended
A rake or hand cultivator
A large bucket or bin with holes in the bottom
Slow release fertilizer
Coconut coir
Perlite – optional (makes the soil lighter)
Soil pH tester – optional but recommended
Gypsum, lime , or other soil amendments as needed to adjust soil pH
Compost and worm castings, optional but helpful
A large compost bin or container for holding your soil
Gloves and mask – Optional, but highly recommended. Discover the best cut resistant garden gloves here.

How to rejuvenate your potting soil

While dealing with soil and soil additives, it is best to use gloves and a protective mask.

1. Lay out your dirt on a tarp or plastic sheet. Get rid of any old roots, plant stalks, or other trash. A full-sized rake or a hand fork may be used to rake through it. Personally, I like to use a hand cultivator as well as a garden kneeler or knee pads.

You may also want to sieve your soil, if you have a garden sifter or sieve set. This is best, but many beginning or small scale gardeners do not have a garden sieve. It’s OK if you’re on a budget and don’t have one. Just rake the dirt as best you can by hand.

Wazakura 3PCS Soil Sieve Set 8-1/4″ (210mm), 3 Sieve Mesh Filter Sizes,…

Size: 8.26 x H 2.55 in (210mm x 65mm) | Sieve mesh sizes: 0.04 in (1mm), 0.11 in (3mm), 0.19 in (5mm) (245g)
One frame with three replaceable mesh screens and interchangeable lids. To change screens, put the bowl upside down and tap the mesh off so it…
Composting and General Gardening Due to its compact size and different mesh types, it is ideal for general gardening tasks (seed separation, rock…

2. Next, you’ll drain the salts from your soil. Many individuals do not do this because they are unaware of how crucial it is. Mineral salt build up in soil, especially if you don’t wanter potted plants until water runs freely out of the bottom. Brown leaf tips, yellowing leaves, wilting, and poor growth are all signs of possible excess mineral salt accumulation in your potting soil. If you’ve already experienced these issues, it’s time to start cleansing your filth!

Transfer the soil to a large bin or bucket with holes in the bottom. A drill may be used to drill holes in any big plastic container.

Fill the container halfway with water and soak the soil until water runs freely from the bottom. Let the dirt to drain completely before flushing it again. Transfer the dirt back to your tarp or plastic sheet after the water has been drained.

When the dirt has dried, use your rake to break up any clumps and flush it again.

4. Add compost and worm castings, if using. If you have a sieve, filter your compost. Mixing a 1:1 ratio of compost to soil will give you nice, rich potting soil to grow in. Worm castings are usually applied at a rate of 10-12 ounces per 5 gallons of soil.

3. Add soaked coconut coir and/or perlite. Up to 40% coconut coir and 10-20% perlite may be used. For best results, use warm water and a very large container when you soak your coconut coir.

5. Test and adjust soil pH. Many people skip this additional step, but it is beneficial. Different plants prefer different acidities, but many vegetables do best with slightly acidic soil with a pH of 5.8-6.5. Many vegetable growers strive for a pH of 6.5 or higher. If your soil pH is less than 5.5 or more than 7.5, you should modify it so that your plants can access nutrients in the oil.

You don’t have to do any complicated science experiments to test your soil pH. Buy an electronic pH soil tester to do the work for you!

Over time, potting soil usually turns more acidic. Lyme and wood ash are two common soil additives used to increase soil pH. There are different forms of lyme and application rates vary, so make sure to read up on how to make your soil less acidic if that’s something you need to do. For acid-loving plants like blueberries, you may need to add aluminum sulfate or sulfur to your soil.

6. To each gallon of soil, add 1 teaspoon of slow release fertilizer. Do you know how much dirt you have? Check the size of your bucket or bin to see how many gallons it contains.

7. Moisten the soil moderately with water and put it in a big bin or compost container for at least two weeks. to allow everything to incorporate into the soil.

Enjoy your awesome rejuvenated potting soil!

Ways to reuse old potting soil

If storing and refilling soil sounds inconvenient, here are a few alternatives for reusing your old potting soil:

Use it to fill in holes in your yard. This is my particular favorite, and I’ve done it several times. Fill it ruts, wash outs, dog holes, spots where your toddler has been digging, etc.
Add it to your compost pile. Avoid introducing plants or soil from any plants that have been infected with disease. Many pant pathogens can remain in soil for years, even if you have a hot compost pile. Are you new to composting? Learn more from a reputable, free source, such as an agricultural extension. Find and contact your local state extension office for particular guidance.
Bury it in a compost hole.
Work it into your flower beds.
Use it to fill the bottom half of raised beds, Fill in with new dirt. (Do NOT do this with diseased soil!)

Frequently asked questions

Q: Can I reuse potting soil from tomatoes?

A: Do not use tomato potting soil to grow tomatoes again for at least three years. They are voracious feeders, sucking up a lot of nutrients from the soil. Tomatoes are also susceptible to illness. These diseases can stay in the soil for several years. Some of them also affect pepper plants, so don’t reuse tomato soil for peppers, either.

B: What can I do with old tomato soil?

A: You may replenish tomato soil and reuse it for a new plant family. Plants that replenish the soil, such as beans and peas, perform well, as do light feeders, such as most herbs, radishes, and kale.

Q: Can you put old soil in the compost bin?

A: Absolutely, as long as the plants were not infected. Do not put diseased soil in your compost pile.

I hope this guide to reusing potting soil helps you! Good luck with your gardening.

Natasha Garcia-Lopez is a happy owner of 88 acres of property in rural West Virginia and an avid home grower. She was a member of the Association for Living History Farms and Agricultural Museums for many years and is currently enrolled in the Oregon State University Master Gardner Short Course program so she can better assist you with your gardening questions. She has a natural skincare diploma from the School of Natural Skincare.