RHS Growing Guides
How to grow potatoes
Our detailed growing guide will help you with each step in successfully growing Potatoes.
Getting Started
This grow-your-own favourite is easy and versatile, ideal for beginners, and harvesting is like digging for buried treasure. Potatoes aren’t just for large veg plots – you can grow a few plants in a small bed or large tub, and even grow a Christmas crop in a greenhouse.
The humble spud comes in a surprisingly diverse range of varieties, offering gardeners a choice of flavours and textures not available to supermarket shoppers. Most varieties are classified as either earlies (new potatoes) or maincrops, depending on when they’re ready to harvest.
Potatoes are grown from specially prepared ‘seed potatoes’ (small tubers), usually planted in spring. With early varieties, the seed potatoes can be ‘chitted’ (or encouraged to sprout) before planting, to get them off to a head start and produce an earlier crop. As the plants grow, soil should be gradually piled up around the stems, known as earthing up, to bury the developing tubers.
If you don’t have room for a whole row of potatoes, you can grow just a few in a small bed or large container. You can even grow a winter harvest by planting in a large tub in late summer, then protecting the plants from frost in a greenhouse or sunny porch.
Potatoes are usually easy and reliable croppers, but they can be affected by several pests and diseases, the most notorious being the fungal disease blight. However, this is less likely to affect early varieties and is less prevalent in dry summers.
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Choosing
There is a huge range of potato varieties to choose from, so it’s well worth trying out some of this rich diversity, rather than sticking to just one. There are various flavours, textures (waxy or floury), sizes and colours (white, yellow or even purple) to discover, with traditional heritage varieties and new disease-resistant options, for various growing conditions and culinary uses.
So there are potato options to suit every taste – far more diversity than you can buy in the supermarket, which is one of the main advantages of growing your own. Potato varieties are classed as earlies or maincrops:
- Early varieties (either first earlies or second earlies) – are ‘new potatoes’, small, sweet and delicious. They’re faster growing, ready to harvest in as little as 12 weeks. The plants take up less space, so are better for smaller plots, and can be grown in containers. As they are harvested by midsummer, they free up space to grow another crop, such as courgettes or beans, for the rest of the summer
- Maincrop varieties are in the ground a lot longer, through to late summer or early autumn. They produce a larger harvest and bigger individual potatoes, ideal for roasting and baking, and can be stored for use in winter
Some varieties are resistant to specific diseases, including scab and blight, so are worth choosing if these have been a problem in the past.
When choosing varieties, look in particular for those with an RHS Award of Garden Merit (AGM – these performed well in trials, so should grow and crop reliably for you – see our list of AGM fruit and veg.
You can also see many crops, including potatoes, growing in the vegetable plots at all the RHS gardens, so do visit to see how they’re grown, compare the varieties and pick up useful tips.
What and where to buy
Potatoes are grown from specially prepared ‘seed potatoes’ (small tubers). These are just like potatoes you buy from the supermarket, but they’re certified virus-free, so should give you healthy, vigorous plants.
You can buy seed potatoes in late winter and spring in garden centres and online. Mail-order suppliers offer the widest choice of varieties and most allow you to order in advance, as specific varieties may sell out.
For a winter (or Christmas) crop in a greenhouse, buy cold-stored tubers in late June or July.
Recommended Varieties
Potatoes — first earlies
Introduced over 60 years ago, high yielding first early, waxy flesh when cropped young.Some slug resistance.
Very early cropping first early. White round tubers, white flesh with good drought and common scab resistance. Good...
One of the earliest of the first early varieties, it can be harvested 8 to 10 weeks after planting in ideal growing...
Sowing
Chitting potatoes
Chitting simply means allowing seed potatoes to start sprouting before you plant them. It’s not essential, but is worthwhile with early varieties to get them off to a head start, so they produce an even earlier crop.
For both first and second early varieties, start chitting in February or March – the process takes four to six weeks:
- Stand the seed potatoes rose end upwards (the end with the most small dents, or eyes) in egg boxes or trays in a cool, bright, frost-free place.
- Once the green shoots are about 3cm (1in) long, the potatoes are ready to plant. With early potatoes, rub off the weakest shoots, leaving only four per tuber.
If you don’t have the time or space to chit your early seed potatoes, they will still grow perfectly well, but will just take a few weeks longer to crop. There is no real advantage to chitting maincrop varieties, as they grow over a much longer period.
Planting
Potatoes are mainly planted in spring, over several weeks, according to the type of variety
- First earlies – plant around late March
- Second earlies – plant in early to mid-April
- Maincrops – plant in mid- to late April
The timing also depends on where you are in the country – plant slightly later in colder regions and earlier in milder ones.
Planting options
To grow an extra early crop – plant chitted seed potatoes of early varieties at the beginning of March, into large containers in a frost-free greenhouse. Keep them indoors in good light for a crop by about mid-May.
To grow a winter (or Christmas) crop – plant prepared (cold-stored) tubers in July or early August, into containers in a greenhouse or similar frost-free location. Keeping them indoors also protects them from blight.
Potatoes need an open, sunny growing site, not prone to late frosts, as the young shoots are susceptible to frost damage in April and May. They like rich, fertile soil, so before planting, dig in plenty of organic matter, such as garden compost or well-rotted manure, especially if your soil is light – see our guide to soil types. If possible, do this the previous autumn or winter. Also apply a general-purpose fertiliser.
To plant, dig a trench 15cm (6in) deep, place the seed potatoes along the base with the sprouts upwards, then cover with at least 2.5cm (1in) of soil and water well. Alternatively, you can dig individual holes for each tuber.
- Earlies – plant 30cm (1ft) apart, in rows 60cm (2ft) apart
- Maincrops – plant 37cm (15in) apart, in rows 75cm (30in) apart
Handle seed potatoes gently, taking care not to damage the shoots, especially when covering them with soil.
Alternatively, you can grow potatoes under black polythene sheets. The crop forms just below the surface in the dark, so there’s no need to earth up the plants (see below). Harvesting is also easier, with little or no digging required.
Take care to grow potatoes in a different location each year, to avoid any build-up of potato pests and diseases in the soil.
Planting in containers
If you don’t have space in the ground, you can grow potatoes in large containers, where they’ll produce a modest but valuable crop. Early varieties are the most suitable, as the plants are smaller and mature more quickly.
Choose a container at least 30cm (12in) wide and deep, and half-fill with 15cm (6in) of multi-purpose compost. Plant one seed potato per 30cm (12in) of pot diameter, setting them just below the surface. Once shoots start to appear, add more compost gradually as they grow, until the container is full.
If the container can be kept in a frost-free location, this is a good way to get an early batch of new potatoes or a very late crop in winter.
Plant Care
Earthing up potatoes
Potato plants need ‘earthing up’ – this means drawing up soil around the stems as they grow – to protect shoots from frost damage in late spring and ensure 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, mound 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).
It’s a similar process for plants in containers. From half-full at planting time, gradually add more potting compost as the stems grow, until the surface ends up just below the pot rim.
When growing potatoes under black polythene sheeting, there is no need for earthing up.
Watering
To ensure a good crop, keep potato plants well watered in dry weather – particularly early on, when the tubers are starting to form.
Potatoes in containers need regular and generous watering throughout the growing season, especially if kept in a greenhouse. Even outdoors, the dense foliage will prevent rainwater reaching the compost, so water even during wet weather to make sure you get a decent harvest.
Feeding
Maincrop potatoes benefit from a nitrogen-rich fertiliser around the time of the second earthing up.
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 fleece overnight, or cover with soil.
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.
Harvesting
Harvesting potatoes is the really fun part – carefully lifting your plants to discover the size of your underground treasure is a thrill that never fades, however many years you’ve been growing potatoes.
But it can be difficult to judge when to harvest, as the crop isn’t visible. So before you dig up your first plant, gently scoup away some of the soil to check on the size of the tubers. Cover them again if you decide they’re not yet big enough.
Early potatoes and maincrop potatoes mature at different times over the summer. Harvest times can also vary across the UK and from year to year, depending on the weather. But as a general guide:
- First early varieties should be ready to lift in June and July
- Second earlies in July and August
- Maincrop varieties from late August through to October
With earlies, wait until the flowers open or the buds drop. The tubers should be the size of hens’ eggs. With maincrops, start lifting them in late summer for immediate use. You can leave them in the ground until needed, and they will keep growing larger, but the longer they’re in the soil, the more likely they are to get damaged by slugs.
Dig up potatoes carefully, inserting your fork at least 30cm (1ft) away from the base of the plant to avoid spearing the tubers. Discard any potatoes that are green, as they’re potentially poisonous.
If you only want a few potatoes at a time, try digging down carefully beside a plant with a trowel – you should be able to remove a few individual potatoes without disturbing the plant’s roots, so it can continue growing.
Potatoes grown in containers are really easy to harvest, without the risk of accidentally damaging them – gently tip out the contents and pick out your buried treasure.
If you want to store maincrop potatoes, delay harvesting until the leaves turn yellow, then cut off and remove all the top growth. Wait for 10 days, then dig up the tubers and leave them in the sun for a few hours to dry, then brush off the soil.
Early potatoes are best cooked and eaten as soon as possible after harvesting. Maincrops can either be used fresh or stored for several months and eaten gradually when needed through the winter.
Store maincrop potatoes in a dry, cool, frost-free place, such as a garage, in paper or hessian sacks, or on slatted trays in the dark (to prevent sprouting). Only store perfect, undamaged potatoes that are fully dry, and brush off any remaining soil. Check them every few weeks for signs of rotting, and enjoy regularly through the winter months. Aim to finish them before early spring, as they’ll start to sprout and shrivel.
Problems
Potatoes are easy to grow and usually produce a large, reliable crop. However, they can be affected by several pests and diseases. The main ones to look out for include:
- Slugs – can eat the tubers, especially maincrop varieties that are left in the ground during damp autumn weather
- Potato blight – this fungal disease causes brown patches on the stems that spread and eventually kill the plants. It’s more prevalent in damp weather from mid-summer onwards, so early varieties are rarely affected. Grow resistant varieties in future years and see our guide to beating potato blight
- Scab – forms rough patches on the skin, but can easily be removed when peeling them and doesn’t affect their flavour. There are several resistant varieties
- To avoid the build-up of potato pests and diseases in the soil, grow potatoes in a new position each year – see our guide to crop rotation.
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