It often happens that too much potting soil is bought at the beginning of the planting season, which then remains until the following year. Can this soil still be used? The question also arises with old soil from flower boxes or pots.
Potting soil in bags
Potting soil that is packaged and stored in a cool and dry place retains its nutrients even after a year and can be used without any problems.
However, if the plastic bag has already been opened or even just torn open and is lying outside, the nutrients have reduced or have been used up. But this earth does not have to be thrown away. It can be enriched as potting soil with slow-release fertilizer (€59.00 on Amazon) or incorporated into the garden soil as mulching material.
An opened bag of potting soil will dry out if stored incorrectly. It is therefore not advisable to use it in pots or flower boxes unless the soil is mixed with garden soil. Dry potting soil can also be incorporated into normal garden soil. Here the earth gradually becomes moist again.
Old soil from flower boxes
The old soil from flower boxes or pots is often completely rooted and should be disposed of. Shred these root clumps and add them to the compost.
If the potting soil is not rooted, it can be incorporated into the garden soil. It is no longer suitable as a basis for new planting. On the one hand there is a lack of fertilizer and nutrients and on the other hand the soil is no longer stable. It would no longer support the plants and would collapse when it rained.
Store potting soil correctly
If potting soil is left over when filling balcony boxes and pots, it can be saved and used later. However, correct storage is crucial here:
- An open bag of potting soil should not be left outdoors
- the rain washes the nutrients out of the earth
- humidity changes the acidity of the earth
- Weed seed invades
- unwanted seedlings use up the nutrients
- Pests seek shelter there
If stored correctly, i.e. sealed, cool and dry, potting soil will last for around twelve months. Afterwards it loses nutrients, but is still optimal for weak eaters (plants with low nutrient requirements). For heavy or medium feeders (plants with heavy or moderate needs), the potting soil should be amended with compost or a slow-release fertilizer before use.
