What is the difference between potting mix, and gardening soil or topsoil? All soils are not created equal! It may surprise you to know that potting mixes are manufactured and have very little soil or organic matter content.
Potting mix is specially blended to hold the correct amount of moisture in a container, and provide a stable growing medium for pot plants. Potting mixes can, over time, become dry, worn out and begin to repel water. It is at this time that we would top up our pots with fresh organic material, like compost. This will add some much-needed vigour to the potting mix and help your potted plants thrive.
Garden soils and topsoils are best mixed at least 50/50 with the native soil to maximise the performance of plants in outdoor planting beds. When used in a container, garden soils and topsoils may stay too moist and promote root rot of your plants.
They also have a tendency to shrink and pull away from the sides of the container when allowed to dry out too much. Our heavy clay soils also become too heavy in the pot, and can set like concrete. Potting soil used in an outdoor planting bed may be too well-draining and the bed could dry out too quickly. It also stops the water from moving freely through the garden, which will impact plant health.
In summary, potting mix is always best in pots, and garden soil is best in the garden. To increase the performance of your potting mix, why not blend 2/3rds potting mix with 1/3 compost?
To assist you in discovering what soil type you might have in your backyard and how to work best with what you have, read our articles on –
- What is soil?
- What soil can I expect to find in my backyard?
- Get to Know Your Soil with pH testing
- Caring for your soil
- Improving your soil
- Which soils and manures will meet your specific needs?
Information in the soil series articles provided by Helen Tuton