Recycling used soil or potting compost from our plants may seem like a challenge, but it is an ecological and economical solution that is attracting more and more gardening enthusiasts. Why throw away this precious substrate when it can be revitalized and reused to give your plants a boost? Discover our practical advice to transform this resource into a major asset for your green spaces.
Why throw away used soil?
Over time, the soil used for your plants loses its essential nutrients, becomes compacted and less fertile. However, that is no reason to get rid of it. Reusing depleted soil avoids waste while contributing to sustainable resource management. With a few simple steps, it can regain its full potential and even surpass its initial quality.
In addition to the ecological aspect, it is also an economic choice. Buying quality potting soil can be expensive, especially if your garden or pots require a large amount of substrate. So why not learn how to give new life to what seems to be used up?
Step 1: Analyze the condition of your soil
Before considering reuse, it is important to diagnose the condition of your substrate. If the soil has been used for plants that are diseased or infested with parasites, it is best not to recycle it immediately. It could transmit diseases or pests to your future plantings. In these cases, specific treatment or prolonged composting will be necessary.
If the soil appears dry, compact and poor, but shows no sign of contamination, you have an ideal basis for revitalizing it.
Step 2: Aerate and decompact
Soil that has been used for several seasons often becomes too compact. The first step in reinvigorating it is to work it mechanically. Use a fork or a claw to break up the lumps and aerate it to allow air to circulate between the particles again.
Our advice: For small volumes in pots, a sieve can be useful for removing dead roots and large debris. This facilitates the reintegration of nutrients and improves the overall structure of the substrate.
Step 3: Add natural amendments
To restore your soil to its full vitality, adding organic matter is essential. Here are some key elements to incorporate:
- Ripe compost: It enriches the soil with essential nutrients and improves its texture.
- Natural fertilizers such as ground horn or bone meal: They provide nitrogen and phosphorus, which are essential for plant growth.
- Ground egg shells: An effective source of calcium for strengthening the cell walls of plants.
- Coffee grounds: Perfect for stimulating beneficial microorganisms, while slightly improving the acidity of the soil.
The addition of these elements not only enriches the soil, but also recreates a balance conducive to plant development.
Step 4: Disinfect the soil if necessary
Disinfection can be considered to avoid any risk of contamination. Solarization is a natural and effective method: spread the soil on a black tarpaulin in full sunlight and cover it with transparent plastic film. The accumulated heat will kill pathogens in a few weeks.
Good to know: for faster disinfection, it is also possible to heat the soil in the oven. Spread it out on a baking sheet and leave it at 90°C for 30 minutes. Be careful not to exceed this temperature, as this may destroy beneficial microorganisms.
Step 5: Rebalance the pH
Over time, the pH of the soil can become too acidic or too alkaline, thus limiting the absorption of nutrients by the plants. Use a pH test kit, available in garden centers, to test your substrate.
- If the soil is too acidic, add agricultural lime.
- If it is too alkaline, an amendment such as peat or sulfur can restore the balance.
The aim is to maintain a pH of between 6 and 7, which is ideal for most plants.
Step 6: Use the revitalized soil with care
Once the soil has been enriched and balanced, it can be used for your new plantings. However, avoid reusing it on its own, especially for demanding plants. Mix it with new potting soil or compost to ensure an optimal nutrient supply. This new composition will be perfect for potted plants, planters or even the vegetable garden.
Some additional tips
- If you have large quantities of soil to revitalize, incorporate it into your compost for a long-term transformation process.
- Use this soil for less demanding plants, such as succulents or aromatic herbs, which require few nutrients.
- Remember to repeat this process every 2 or 3 years to maintain a quality substrate.
