Outdoor plant boxes are a fantastic way to grow herbs, vegetables, and flowers, but maintaining soil fertility is key to a thriving garden. Certain plants naturally enhance soil quality by fixing nitrogen, adding organic matter, or improving soil structure. Here are the best plants to boost fertility in your outdoor plant boxes:

1. Legumes (Beans, Peas, Clover) – These nitrogen-fixing plants convert atmospheric nitrogen into a form usable by plants, enriching the soil naturally.

2. Comfrey – A dynamic accumulator, comfrey pulls nutrients from deep in the soil and stores them in its leaves, which can be used as mulch or compost.

3. Marigolds – Known for pest control, marigolds also improve soil health by suppressing harmful nematodes and adding organic matter when decomposed.

4. Buckwheat – A fast-growing cover crop that prevents erosion, suppresses weeds, and adds phosphorus to the soil when tilled back in.

5. Borage – This herb attracts pollinators and accumulates trace minerals, enhancing soil fertility when its leaves decompose.

By incorporating these plants into your outdoor plant boxes, you can create a sustainable, nutrient-rich environment for all your gardening needs. Rotate crops and use organic mulches to further enhance soil health for long-term success.