Potatoes - Growing Your Own / RHS Gardening

Earthing up potatoes 

Potato plants are traditionally ‘earthed up’, which means mounding up soil around the stems as they grow. This protects the shoots from frost damage in late spring and ensures the developing potatoes aren’t exposed to light, which turns them green and inedible. It’s a simple process – once the shoots are about 23cm (9in) tall, draw soil up around them to form a ridge along the row, leaving just the top 10cm (4in) of the plants visible. As the stems grow taller, repeat the process several times, a few weeks apart. The final height of the ridge should be 20–30cm (8–12in). But if you are unable to earth up, or don’t have time, you should still get a good crop.

Follow a similar process for potatoes in containers. From half-full at planting time, gradually add more potting compost Can refer to either home-made garden compost or seed/potting compost: • Garden compost is a soil improver made from decomposed plant waste, usually in a compost bin or heap. It is added to soil to improve its fertility, structure and water-holding capacity. Seed or potting composts are used for growing seedlings or plants in containers - a wide range of commercially produced peat-free composts are available, made from a mix of various ingredients, such as loam, composted bark, coir and sand, although you can mix your own. as the stems grow.

Watering 

To ensure a good crop, water potato plants in dry weather. Potatoes in containers need regular watering throughout the growing season, especially if kept in a greenhouse. Even during wet weather it may be necessary to water outdoor containers, as the leaves can act like an umbrella over the compost Can refer to either home-made garden compost or seed/potting compost: • Garden compost is a soil improver made from decomposed plant waste, usually in a compost bin or heap. It is added to soil to improve its fertility, structure and water-holding capacity. Seed or potting composts are used for growing seedlings or plants in containers - a wide range of commercially produced peat-free composts are available, made from a mix of various ingredients, such as loam, composted bark, coir and sand, although you can mix your own. , preventing rainwater soaking down.

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Feeding 

Potato plants growing in the ground don’t generally need feeding, but on poor soil, maincrop potatoes benefit from a nitrogen-rich organic fertiliser around the time of the second earthing up. See the Preparing the Ground sectionfor information on adding nutrients To grow well, plants need a wide range of nutrients in various amounts, depending on the individual plant and its stage of growth. The three key nutrients usually taken up from the soil are nitrogen, phosphorus and potassium. Plants also need carbon, oxygen and hydrogen to make carbohydrates — their main energy source. Carbon and oxygen come from the air as carbon dioxide, while hydrogen is drawn from water absorbed by the roots. Other important soil nutrients include magnesium, calcium and sulphur. Most garden soils contain enough of these nutrients to support healthy plant growth. before planting.

Potatoes grown in containers will need feeding, so either mix an organic general-purpose fertiliser into the compost Can refer to either home-made garden compost or seed/potting compost: • Garden compost is a soil improver made from decomposed plant waste, usually in a compost bin or heap. It is added to soil to improve its fertility, structure and water-holding capacity. Seed or potting composts are used for growing seedlings or plants in containers - a wide range of commercially produced peat-free composts are available, made from a mix of various ingredients, such as loam, composted bark, coir and sand, although you can mix your own. before planting, or use an organic liquid feed when nutrient levels in the compost start to get low (after about six weeks for many peat-free multi-purpose composts).

Weeding

Weed regularly for the first month or two after planting, so the young plants don’t have to compete for light, water and nutrients. Once potato plants are growing strongly and have plenty of leaves, weeding isn’t usually necessary as they will generally shade out any competition. Repeated earthing up Mounding soil up around plants, usually specific vegetable crops. With potato plants, it protects early shoots from frost and ensures new tubers aren’t exposed to light, which can make them green and poisonous. With tall or top-heavy plants such as brassicas, it helps to prevent windrock, which can loosen the roots. Leeks and celery are earthed up to blanch the stems. also helps to deter weeds.

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Protecting from frost

Frost can damage young potato plants, so if freezing temperatures are forecast after shoots have appeared, protect them with a cloche or some hessian or straw overnight, or cover with soil or garden compost Can refer to either home-made garden compost or seed/potting compost: • Garden compost is a soil improver made from decomposed plant waste, usually in a compost bin or heap. It is added to soil to improve its fertility, structure and water-holding capacity. Seed or potting composts are used for growing seedlings or plants in containers - a wide range of commercially produced peat-free composts are available, made from a mix of various ingredients, such as loam, composted bark, coir and sand, although you can mix your own. . With plants in containers, keep them in a frost-free place such as a greenhouse until there’s no longer any risk of frost outdoors.