How to Grow Potatoes in Bags – UK Container Growing Guide

Home-grown potatoes are one of the great pleasures of a kitchen garden. The difference between a waxy new potato dug from the ground an hour before eating and a supermarket equivalent stored for weeks in a warehouse is dramatic enough to convert almost anyone to growing their own. Potatoes are also one of the most forgiving crops for beginners – they are relatively tolerant of imperfect conditions, produce abundantly and give immediate, visible results that make them enormously satisfying to grow.

Understanding the difference between first earlies, second earlies and main crop varieties – and how the timing of each fits the UK growing season – is the essential starting point for a successful potato harvest.

Choosing the right variety

Chitting seed potatoes

Chitting is the process of allowing seed potatoes to sprout short, sturdy shoots before planting. It is not strictly essential but it gives plants a head start and typically brings the harvest forward by 2-3 weeks – particularly valuable for first earlies where every week counts.

1. 1
   Start chitting from late January or FebruaryPlace seed potatoes rose-end up (the end with the most eyes) in egg boxes or seed trays in a cool, light, frost-free location. A spare bedroom windowsill or cool porch is ideal. Avoid dark sheds where shoots will become pale and leggy.
2. 2
   Allow 4-6 weeks of chitting before plantingIdeal sprouts are short, dark green and stocky – 1-2cm long. If sprouts are long and pale the location is too dark or warm. Remove any very long pale sprouts and move to a brighter cooler spot.
3. 3
   Rub off excess sprouts before plantingLeave 2-3 of the strongest sprouts per tuber and rub off the rest. Concentrating growth into fewer sprouts produces stronger plants and larger tubers than allowing all eyes to develop.

Planting correctly

Plant first earlies from mid-March (south) or early April (north), second earlies from early to mid-April and main crop from mid to late April. Plant timing is governed by soil temperature and frost risk – potatoes are damaged by hard frost, though light frost on emerging foliage rarely causes serious harm.

• Planting depth – 10-15cm deep, rose end up
• Spacing first and second earlies – 30cm apart in rows 60cm apart
• Spacing main crop – 38cm apart in rows 75cm apart
• Soil preparation – dig in generous compost or well-rotted manure before planting. Potatoes are heavy feeders that respond dramatically to rich soil.

Earthing up

Earthing up – drawing soil up around the emerging potato stems – is one of the most important care tasks and one that many beginners skip. It serves three purposes: protecting emerging shoots from frost damage, preventing tubers near the surface from turning green (green potatoes contain solanine and must not be eaten), and encouraging the development of more tubers along the buried stem.

Begin earthing up when shoots are 10-15cm tall. Draw soil up from either side of the row using a hoe or by hand, creating a ridge that covers all but the top 5cm of foliage. Repeat every 2-3 weeks as growth continues until the ridges are 20-25cm high. In a dry spring water the rows thoroughly before earthing up.

Care through the season

• Water in dry spells – potatoes need consistent moisture particularly when tubers are forming. A dry period during tuber bulking produces hollow or misshapen potatoes. Water deeply every 7-10 days in dry weather rather than light daily watering.
• Watch for blight – potato blight (Phytophthora infestans) appears as brown patches on leaves in warm, wet conditions typically from July onwards. Remove affected foliage immediately and cut down haulm if blight spreads rapidly to prevent it reaching the tubers. Blight-resistant varieties like Sarpo Mira resist infection significantly better than susceptible varieties like King Edward.
• Protect from slugs – slugs burrow into developing tubers underground and the damage is only discovered at harvest. Nematode treatment applied in July and August reduces slug populations significantly.

Harvesting

First earlies are ready when the flowers open – typically late June to July. Push a hand into the soil beside the plant and feel for tubers. If they are marble-sized or larger, they are ready. Harvest by pushing a fork in well to the side of the plant and lifting the whole root system.

Main crop potatoes are ready when the foliage (haulm) has died back naturally – typically August to October. Cut down the haulm and leave tubers in the ground for 10-14 days to allow skins to set before harvesting. Lift on a dry day and allow to dry on the surface for a few hours before storing in paper sacks or hessian bags in a cool, dark, frost-free location. Properly stored main crop potatoes keep through to the following spring.

For more on productive vegetable growing read our guides on how to grow tomatoes UK and our April gardening jobs UK for what else to plant this month.