Can you reuse soil in plant pots? Here’s why you shouldn’t throw it away just yet

If your pot plants have finished flowering or are no longer looking their best, you might be wondering if you can reuse soil in plant pots to save on buying a new bag of compost.

Thanks to the ever-climbing cost of living, we're living in an age of 'waste not, want not'. While there are plenty of eco-friendly garden ideas that mean you can reuse old pots or try your hand at rain harvesting. When it comes to recycling something like soil things can feel a little more complicated.

'If you have a portable garden or use containers for planting, you will know there can be plenty left over at the end of summer which you won’t want to go to waste,' says Morris Hankinson, director of Hopes Grove Nurseries.

However, there are ways to put your old potting compost to work again...

Can you reuse soil in plant pots?

It's good news for thrifty gardeners, as Christopher O'Donoghue of Gardens Revived says 'You can reuse soil in plant pots, but it needs some rejuvenation before planting again to ensure it's still fertile and healthy for new plants'.

Christopher O'Donoghue

An RHS-trained gardener with almost two decades of experience under his belt, Christopher set up Gardens Revived with his brother, Andrew, in 2018 to create a thriving family business. Together, they have worked on residential gardens, listed buildings and gardens, flower shows and large estates with some exceeding 70 acres – many with historical significance.

How to make old potting soil good again

1. Remove and refresh

If you want to reuse soil in plant pots, it's important to remove any old plant debris and add some nutrients back in before you get started.

'Clear out roots, stems, and any remaining plant material from the previous use,' says Christopher.

'It's important to remember that, over time, the soil loses nutrients. Try mixing in compost, well-rotted organic matter, or a slow-release fertiliser (like the Miracle-Gro All Purpose Continuous Release Plant Food from Amazon) to help restore fertility.'

2. Improve and rotate

Adding materials such as perlite, sand, or fresh potting mix (like Miracle Gro All Purpose Peat Free Compost from B&Q) to old soil in plant pots will help improve drainage and aeration if the soil has compacted.

Christopher says that you should also rotate plant types to improve soil condition.

'Avoid replanting the same species in old soil, as this helps to reduce nutrient depletion and minimise the risk of disease,' he adds.

3. Avoid reusing infected soil

There is one big exception to the rule of reusing old soil: avoid recycling any that shows signs of pests or diseases.

'Examine the soil for signs of pests or fungal infections,' says Christopher. 'If there are any present, you can sterilise the soil (by baking it in the sun or oven), but personally I'd avoid reusing it.'

How to recycle old soil

You don't have to reuse soil in plant pots – it can also be incorporated into other parts of your garden, too.

'Old compost from pots can also be dug into existing flower beds which can help to improve structure of the soil and fill beds,' says Morris.

'And, if you aerate your lawn in autumn, you can always mix some old pot compost with sand and apply with a rake over the top of your lawn to give your lawn a boost.'

FAQs

Do you need to change soil in outdoor potted plants?

While some experts advise replacing the soil in your outdoor potted plants (or at least topping it up) every 12-18 months of so, you can reuse soil in plant pots if you're careful to rejuvenate the soil.

'Old compost can be tipped out of the pot and have some other well rotted organic matter incorporated,' says Morris Hankinson of Hopes Grove Nurseries.

'The new organic matter will give it a boost and make it reusable again for growing. Make sure the mix is about one third new organic matter and two thirds old compost, and take care to remove any old roots and plants.'

How many times can potting soil be reused?

The number of times your potting soil can be reused is entirely dependent on circumstance. As a general rule of thumb, though, it's a good idea to replace the soil or spend some time sterilising it if your plants show any signs of pest or disease.

Now that you know you can reuse soil in plant pots, you'll likely have more money to spend on autumn flowers and perennials. Race you to the checkouts...