Do herbs need special soil in containers?
Written by
Paul Reynolds
Reviewed by
Prof. Samuel Fitzgerald, Ph.D.Container herbs love specialized soil mixtures , a standard garden soil will not do, nor will the ordinary bagged mixtures that are sold as a potting compost (many urban mixes add in salt from mineral soil that can rot the roots of your plant). Some Mediterranean herbs, such as excellent drainage, while moisture-loving herbs like basil thrive in water-retentive composts. Using incorrect soil is like inviting death by drowning or dehydration. Still, your herbs will thank you instantly if you adequately prepare the soil for them.
Mediterranean Herbs
- Mix: 3 parts potting soil + 1 part coarse sand + 1 part perlite
- Drainage: Minimum 30% inorganic material
- pH: Maintain 6.0-7.0 for nutrient uptake
Moisture-Loving Herbs
- Mix: 2 parts potting soil + 1 part compost + 1 part coconut coir
- Water Retention: Coir holds 8x its weight in water
- pH: Slightly acidic 6.0-6.8 preferred
General Container Mix
- Mix: 3 parts potting soil + 1 part perlite + 1 part worm castings
- Versatility: Works for parsley, chives, oregano
- pH: Neutral 6.5-7.0 ideal
Create these gritty Mediterranean mixes for rosemary and thyme to prevent waterlogging in their root zones. Use potting soil mixed with judicious amounts of drainage materials, such as perlite or pumice, as long as the combination isn't too muddy. Please conduct a quick watering test; excess water should exude within 10 seconds. My rosemary loves it since the change.
Combine water-retaining soils for basil that is sensitive to moisture. Coconut coir is a more sustainable option, as well as being lower in pH, compared to peat moss. Pre-moisten your coir before mixing it into the soil to kick-start absorption. Keep soil moist, but not saturated at all times. Self-watering containers work very well with these soils.
Monitor soil pH for its effect on any herb. Mediterranean herbs dislike acidic conditions. These combinations below 6.0 can be too hot to handle. Add dolomite lime and test regularly, at least in spring and fall. Kits give fast readings. Amendments will stop nutrient lockout. My oregano was noticeably greener after correcting the soil.
Refresh container soil annually. Herbs quickly use up nutrients in their limited space, so replanting should top up the soil to a depth of 3 inches every spring. Add slow-release fertilizer to the new layer at this time, and your herbs will continue to thrive year after year.
Read the full article: 10 Best Herbs for Container Gardening Success
