Mounding soil around the base and lower stems of a plant as it grows. Used for potatoes (to prevent greening and increase yield), leeks (to blanch stems), and celery (to blanch and sweeten).
Earthing up, also called ridging or hilling, involves drawing soil up around the stem and lower leaves of plants as they grow. This technique serves multiple purposes in Australian gardening. For potatoes, earthing up prevents tubers from being exposed to light, which would turn them green and toxic. Start earthing up when shoots are 15cm tall and repeat every 3-4 weeks through spring and early summer. For leeks and celery grown in temperate zones (zones 7-9), earthing up blanches the stems, producing tender, pale white sections prized for cooking. The practice also provides extra root support during strong spring winds and improves drainage around plant bases, crucial in areas prone to waterlogging during autumn and winter rains.
Earth up using loose, well-draining soil mixed with compost from your local Bunnings or garden centre. Avoid compacting the soil, as roots need oxygen. In warmer northern zones (1-3), earthing up helps keep soil cooler around roots during hot summers. The technique also smothers emerging weeds and reduces the need for herbicides, making it ideal for organic gardens. Time your earthing up during spring and early summer when plants are actively growing and soil moisture is adequate.