Growing Potatoes in Bags: Container Size & Care Guide

Illustration of potato grow bags and a basket of harvested vegetables

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Growing potatoes in bags or containers is an effective way to produce a harvest without needing a dedicated vegetable plot. To succeed, you need a container at least 30cm wide and deep, a nutrient-rich peat-free compost, and a routine of “earthing up” to protect the developing tubers from light. Early potato varieties are generally the most suitable for bag growing because they mature quickly and have smaller plant footprints.

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Selecting the right container and size

The choice of container directly impacts the volume of tubers you can harvest. A standard requirement is a container at least 30cm in width and depth. You can use dedicated potato grow bags, sacks, or repurposed large compost bags, provided you pierce holes in the bottom to ensure adequate drainage.

Choosing potato varieties for bags

Potatoes are categorised by their harvest time, which influences their suitability for containers:

First and second earlies: These are the most recommended for bags. They grow faster, take up less space, and are often ready to harvest in as little as 12 weeks.
Maincrops: While possible to grow in larger containers, these stay in the soil longer and produce larger tubers, requiring more sustained nutrient levels and space.

Choose certified seed potatoes and follow the variety’s normal planting window. A late protected crop needs a separate growing plan and is not a dependable extension of an outdoor summer crop.

Planting routine and initial setup

Before planting, early varieties can be “chitted” (encouraged to sprout) in egg boxes in a cool, bright spot for four to six weeks. This gives the plants a head start.

To plant in a bag or pot:

Fill the container partially with peat-free multi-purpose compost. For a container at least 30cm wide and deep, the RHS method starts with about 15cm of compost.
Allow roughly one seed potato per 30cm of pot diameter; position it with the sprouts facing upwards.
Set the tuber just below the compost surface, taking care not to damage the sprouts, then add more compost gradually as shoots develop.
Position the bag in an open, sunny site. If planting early in spring, keep containers in a frost-free greenhouse until the risk of frost has passed.

Routine care: Earthing up and feeding

Earthing up is the process of gradually adding compost around the stems as the plant grows. This is critical because if tubers are exposed to light, they turn green and become poisonous.

Add compost gradually around developing stems according to the bag-growing method, keeping growing foliage exposed and tubers covered. Stop below the rim with space for watering; do not heap compost until shoots are buried.

Because container-grown potatoes cannot draw nutrients from the wider ground, they require supplemental feeding. You can either mix an organic general-purpose fertiliser into the compost before planting or apply an organic liquid feed when the compost’s initial feed runs low, often after about six weeks; follow the compost and fertiliser labels.

Watering and pest management

Potatoes in bags dry out faster than those in the ground. Regular watering is essential throughout the growing season, particularly for plants in greenhouses. It is important to note that dense foliage can act as an umbrella, preventing rainwater from reaching the compost even during wet weather; therefore, manual watering may still be necessary.

Common issues in container growing include:

Blight: While less prevalent in dry summers and less likely to affect early varieties, blight can attack foliage and tubers. Check foliage and tubers and follow disease-specific advice if symptoms appear.
Slugs: These can tunnel into tubers, especially maincrops during damp autumn weather.
Frost: Young shoots are susceptible to damage in April and May. Protect them with cloches, hessian, or by keeping them in a frost-free environment.

Harvesting and storage

Harvesting from bags is simpler than digging in the ground. For early varieties, harvest around the variety’s expected harvest time, checking a sample because not every plant flowers, and the tubers are roughly the size of hen’s eggs. For maincrops, wait until the leaves turn yellow, remove the top growth, and wait 10 days before lifting.

To harvest, gently tip the contents of the bag onto a flat surface and pick out the tubers by hand. Discard any potatoes that have turned green. Use early potatoes soon after harvest; their thin skins make them less suitable for long storage. Maincrops can be stored in a cool, dry, frost-free, and dark place (such as a garage) in paper or hessian sacks to prevent sprouting.

Useful products for this job

The links below open Amazon UK product searches. Check the exact item, seller, current price and compatibility before buying.

Peat-free multi-purpose compost: Required as the primary growing medium for potatoes in bags to provide drainage and initial nutrients. Ensure it is specifically labelled as multi-purpose and peat-free for environmental sustainability. Search Amazon for Peat-free multi-purpose compost.
Potato grow bags: Specialised containers that often include a flap at the bottom for easier harvesting without tipping the whole bag. Check for drainage holes at the base; if using repurposed sacks, these must be added manually. Search Amazon for Potato grow bags.
Organic liquid fertiliser: Replenishes nutrients when the compost's initial feed runs low. Verify the fertiliser is organic-based and suitable for root vegetables. Follow the compost and feed labels to avoid doubling up fertiliser. Search Amazon for Organic liquid fertiliser.

Another supplier for this job

Elixir Garden Supplies is an affiliate partner. We may earn commission from purchases through these links. Check the selected product, current price and delivery terms.

EcoGreen Peat-Free Compost: A peat-free option for suitable container growing and potting on. Choose the volume needed and read the growing instructions; it is not suitable for ericaceous plants. View EcoGreen Peat-Free Compost at Elixir Garden Supplies.

Related garden guides

Sources and further guidance

Guidance researched in September 2026. The feature image is an AI-generated illustration. Product guidance is based on published information, not hands-on testing.