How often should raised bed soil be replaced?
Written by
Benjamin Miller
Reviewed by
Prof. Charles Hartman, Ph.D.If cared for properly, raised bed soil does not need to be completely replaced. I've seen beds older than a decade and only the top layers have needed amending with fresh soil. Clients have reported back not to waste their time on beds because they thought they were "dead" when solutions were often very cheap and easy. We should focus on renewing compost each year, rotating crops, and pH monitoring instead of spending hundreds or thousands replacing soil.
Annual Compost Refresh
- Amount: 6" depth across the bed surface
- Benefits: Replenishes microbes and nitrogen
- Method: Mix into topsoil with a garden fork
Crop Rotation Strategy
- Cycle: Leaf → fruit → root crops yearly
- Impact: Prevents 70% of soilborne diseases
- Example: Follow tomatoes with beans for nitrogen fixation
pH Testing Protocol
- Frequency: Every 90 days during growing seasons
- Tools: $15 digital meter or test strips
- Adjustments: Lime (raises pH) or sulfur (lowers pH)
Assess the soil health before considering replacement. A straightforward test: grab a handful of soil and squeeze; if it falls apart like a chocolate cake, it is usable. If it is extremely hard, like concrete, add some aeration with 30% coarse sand and compost. I once had a client who added worms and a bit of aged manure to a bed she was going to replace because she said it was "dead". We harvested bumper crops from that bed; it was great!
Replacing everything is wasteful. Refreshed beds are only $0.80/sq ft per year compared to $4/sq ft for new soil. Sustainable approaches also help to maintain beneficial fungal connections, which can take 3-5 years to replace after a replacement. Keep track of your improvements with photos along with yield logs, and it will inspire you to continue with this practice.
Read the full article: 7 Expert Tips for Perfect Raised Bed Soil Every Time
