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Repotting houseplants might seem like a simple task but there is always a risk that plants may not do well after repotting. Removing old soil from roots can ensure that the plant does not succumb to transplant shock.

Removing old soil from roots when repotting will get rid of salt buildup around the roots as well as ensure the roots are surrounded by new soil which will be rich in minerals and nutrients. Exposing the roots will also allow the opportunity for root sterilization to remove unwanted fungus or disease before repotting.

Container-grown plants require occasional repotting to keep them healthy. One should know when to repot a plant as well as how to safely re-pot a houseplant. 

In this article, we have answered all your queries related to what to do with the old soil around roots while repotting. 

Why Should Old Soil Be Removed When Repotting

It is necessary to re-pot the newly bought plant as soon as you get home because the soil in which it is sold can vary depending on where you have purchased the plant and the care it was receiving while it was there.

However, the plant can remain in the container it came from for some time if the soil in the container is of good quality. 

See our post on how long can a plant remain in nursery pots and containers to get a better idea on how long you can leave it without repotting.

One of the main reasons for removing the old soil is to remove any disease the roots may have developed over time.

The second reason can be the attack of harmful pests. With the whole or part of soil around roots being infected, the best way to get rid of it is to completely remove it. 

Generally, people can struggle with a lot of problems related to potting or ground soil. 

The problems can be the result of poor quality potting mix or because the pest lives in the ground. 

In such cases, it is ideal to immediately re-pot the plant to remove that old soil and renew it. The health of plants will improve and they can thrive better.

If the old soil is removed from the plant roots, it has a direct effect on the vitality of the plants growing in pots. 

The soil is the most important growth medium for plants, providing them the necessary nutrients and moisture for proper growth. 

The used soil with plants growing in it should be replaced every one or two years for best results in container gardening.

How To Safely Remove / Wash Old Soil From Roots?

Washing the roots of your plants is simple and very easy to do. Just pour water! But be very careful, because choosing the right time to wash can be crucial.

Start removing the soil from the bottom and gently pull the roots away from the current structure that they have created within the pot or ground. 

You can remove the excess soil around the edge of the root ball by hand or with a toothpick. 

A toothpick is an ideal tool to gently remove any bags of hardened soil around the roots. Next, carefully rinse the root ball using a gentle stream of water.

Remember that “removing the soil”, or even a simple transplant is going to damage the roots. You will want to minimize root damage as much as possible. 

Therefore, you need to balance “removing the soil” with damage. In such a situation, the ultimate solution is to break away the edges of the soil and note the “central core”. 

The latter could cause a lot of damage to the plant. 

While repotting a plant in a pot and removing the soil from the roots, you can remove up to a quarter of the roots. 

You can see our article on how long a plant can survive outside a pot to gauge which plants are more resilient to having their roots exposed.

NOTE: For growing new roots and letting the old roots establish themselves in new environments, spring is the perfect season. Repotting a plant during this time of the year, the roots will be ready to grow and will bounce back very soon. 

Therefore, if you want to remove old soil from the roots, do it in spring.

Should The Roots Be Sterilized Before Repotting?

Root diseases can cause considerable crop losses, increased fungicide, and decreased crop quality. 

There are a number of helpful tips that, when followed, can help improve the growing environment to reduce potential outbreaks of plant diseases. Sterilizing the roots before repotting is one of them.  

Remove your plants from the pot and if possible, cover the soil with mesh or concrete to minimize the movement of fungal spores from the soil to the surrounding.

Disinfect tools that come in contact with plant roots.

Sterilize Potting benches, potting machinery, and tray fillers to remove disease inoculants.

NOTE: Do not reuse the potting soil as it may be contaminated, which could explain why some plants appear weak and do not do well after repotting. 

Should The Plant Pot Also Be Washed and Sterilized Before Repotting?

Whether you’re using a new pot or an old plant pot, giving it a thorough wash is important. Some plants are so sensitive to fungi and bacteria present in old or dirty pots that they can die. 

Therefore, it is highly significant that you first wash and sterilize plant pots before repotting. 

Washing new plant pots, especially if you are repotting in terracotta pots, before repotting can also help in keeping the soil moist and drying out during the first few sensitive hours of repotting where a plant may suffer from transplant shock. 

In the case of old plant pots, washing them is important because soil and mineral salt build up inside the old pots can seriously damage plants. 

The salt build-up in old pots may also carry fungal disease formed in the last season and transfer it to your new plants. 

Hence, it is better to be safe than sorry.  Always wash and sterilize your old plant pots before repotting. 

Proper Way To Wash and Sterilize Plant Pots:

Although it is advisable not to reuse old plant pots, however, if you must reuse them, sterilize them first. 

Start with removing and washing any old soil or dirt clinging inside and outside of your old pots. Next, gently scrub your old plant pot using a brush and water. 

Once the old pot gets thoroughly cleaned, soak it in a product that contains quaternary ammonium compounds, hydrogen dioxide, hydrogen peroxide, or peroxyacetic acid, or use bleach to kill pathogens. 

In the case of bleach, use 10% bleach and 90% of water to make a good solution. Place the pot in the container for at least ten to twenty minutes. 

This will, hopefully, kill off any fungal disease lingering around your pot. 

Other Repotting Mistakes To Avoid:

Many gardeners make some mistakes when repotting the plants which should be avoided to have a healthy plant in your garden.

 Always keep the following mistakes in mind to avoid the next time you report your plants: 

• Unnecessarily repotting the plant: Remember, in larger pots, the water gets completely absorbed by the soil before even reaching the roots.

• Repotting into something too large: It’s always best to report into something only an inch or two larger, especially for plants like English ivy, pothos, hoya, succulents that are slow growers or prefer a tight container.

See our article on how container size affects plant size.

• Planting too deeply: You should be able to see the original soil surface after repotting. Burying the stems too deep usually causes them to die because they have a different cell structure than roots. Keep the soil level the same. All new soil goes beside and under the root ball.

• Not leaving a reservoir at the top: If you fill the pot up to the top, water will run through the pot and will not get enough time to get absorbed till roots. For small plants, pot up so that about 1/2? to 1? of space remains between the soil and the rim of the pot.

The Takeaway:

To conclude, always remove the old soil from roots when repotting. Sterilize the tools that come in contact with your plant roots while repotting to avoid introducing any disease. 

Avoid reusing old pots as they can carry and transfer fungal disease or pests. To wash and sterilize the plant pots, soak your pot into a 10% bleach and 90% water solution. 

Water the plant after repotting to let your plant adjust to a new environment. 

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