Green Manures & Cover Crops: The Complete Walkthrough
This guide covers green manures & cover crops, rated an easy task, typically taking 6–12 weeks.
This is the expanded version of our green manures & cover crops guide, for anyone who wants the full detail rather than just the quick-reference card.
Grown to be dug back in
A cover crop like clover, mustard, or field peas is sown into an empty bed, then cut and dug in (or left as mulch) before it seeds — adding organic matter and, for legumes, fixed nitrogen back into the soil.
Getting Set Up
A few things matter most here:
- Cover crop seed suited to your climate and goal (e.g. clover, mustard, field peas, oats)
- An empty bed between main crops
- A mower, slasher, or secateurs for cutting back before digging in
Step by Step
The key things to get right:
- 1. Choose a cover crop suited to the season and your goal — legumes for nitrogen, brassicas like mustard for pest/disease break, grains for biomass.
- 2. Sow densely across the bare bed.
- 3. Let it grow until just before flowering, when nutrient content peaks and it hasn't yet set seed.
- 4. Cut it down and either dig it into the top layer of soil, or leave it as a mulch (no-dig approach).
- 5. Wait 2–3 weeks after digging in before planting the next crop, to let initial breakdown occur.
Troubleshooting
A few things matter most here:
- Cover crop sets seed and becomes a weed — cut it back before flowering finishes; don't leave it too long.
- Poor germination — often from a dry surface; water in well after sowing.
- Slow breakdown after digging in — very woody or mature growth breaks down slowly; cut earlier and smaller next time.
- Not enough time between main crops — choose a fast-cycling cover crop, or skip a full cycle and use mulch instead.
Keeping It Going
Best time — any gap between main crops, or over an entire winter/off-season on a bed that would otherwise sit bare. Duration: 6–12 weeks depending on the cover crop chosen and the season. Maintenance — minimal once established; mainly timing the cut-back correctly. Signs of success — vigorous, dense green growth about to flower, ready to be cut and incorporated.
That's the full walkthrough. The printable A4 quick-reference card for this is on the main guide page below.