Green manures are an excellent way to enrich soil, suppress weeds, and improve the overall health of your outdoor plant boxes. These cover crops are grown specifically to be turned back into the soil, adding organic matter and nutrients. Here are some of the best plants for green manures in outdoor plant boxes:

1. Clover (Trifolium spp.) – A nitrogen-fixing plant that improves soil fertility and attracts pollinators.

2. Buckwheat (Fagopyrum esculentum) – Fast-growing and great for weed suppression, while also attracting beneficial insects.

3. Winter Rye (Secale cereale) – Ideal for cold seasons, it prevents erosion and adds organic matter when tilled.

4. Alfalfa (Medicago sativa) – Deep-rooted and drought-resistant, it breaks up compacted soil and fixes nitrogen.

5. Mustard (Brassica spp.) – Helps control pests and diseases while adding biomass to the soil.

By incorporating these green manure plants into your outdoor plant boxes, you can create a sustainable, nutrient-rich environment for future crops. Rotate them seasonally for the best results!