Gardeners looking to boost their herb gardens may find the answer in a common kitchen waste item: eggshells. While leafy herbs like basil and mint benefit from nitrogen-rich fertilisers, woody herbs such as rosemary, thyme, and lavender require a different approach. Nitrogen can weaken these Mediterranean herbs, dilute their flavour, and increase disease susceptibility.
Herbalist Vladka Merva, founder of Simply Beyond Herbs, recommends using crushed eggshells to strengthen woody herbs. “Eggshells are a great source of calcium that seeps into the soil as you water it,” she explained. Calcium helps maintain soil chemical balance, improves water penetration, and promotes root development, warding off diseases like blossom end rot. It also makes soil more alkaline, which lavender and rosemary prefer.
Additionally, crushed eggshells act as a natural pest deterrent. “Slugs, cutworms or other insects are put off by the crashed pieces of eggshells and rather leave,” Merva said. To use, dry the eggshells completely, crush them with a rolling pin, and sprinkle into the soil of your woody herbs.
For indoor herbs, eggshells can even serve as biodegradable plant pots. Remove the top of an egg, wash thoroughly, and prick a small hole in the bottom for drainage. Fill with a light, sandy, slightly alkaline soil mix, sow seeds, and place in a sunny spot. With regular watering, you’ll soon have a flourishing herb garden.
