how to plant, grow & care for potatoes
complete growing guide
Potatoes have been the staple vegetable in the UK for over a century, providing the energy, vitamins and butter absorbing abilities for almost every meal. Luckily they are also very easy to grow, and perhaps the best vegetable to get children interested in growing their own. Nothing beats the magic of planting a single seed potato and a few months later returning to uncover a haul of buried treasure – anything up to twenty delicious fresh potatoes that just need a quick scrub before going in the pot. You can even grow them on a balcony in a container or plastic bag, so a garden is not a prerequisite. There are so many varieties to choose from we have selected what we believe to be the best from a taste perspective – giving you a range of seed potatoes for every culinary purpose you can come up with.
- Common name: Potato
- Latin name: Solanum tuberosum
- Type: Tender perennial vegetable
- Height & Spread: 45cm x 75cm depending on variety
- TLC rating: Easy
- Aspect: Full Sun, Part Shade
- Spacing: 30 - 75cm depending on variety
- Yield: From 1-2kg
- Suitable for pots: Yes
- Grow in a greenhouse? Yes, if forcing an early or Christmas crop.
how to grow potatoes
where to grow potatoes
Soil type: Potatoes are not too fussy about the soil, although the yield will be greatly improved if you have lovely deep, moist and fertile soil, with plenty of organic matter.
Aspect & position: Potatoes prefer a relatively cool environment, but they do benefit from plenty of light – so an open position, away from any frost pockets or sun traps.
when to plant potatoes
Start chitting your potatoes in January. Plant earlies in March-April and plant maincrop potatoes in April or even May. You can also plant potatoes in bags in August to produce a crop for Christmas.
how to plant potatoes
Potatoes are very sensitive to frost once their leaves are above ground, so do not be tempted to plant them too early. You can get ahead by ordering your seed potatoes and setting them out to start sprouting in a protected area early in January. This is known as “chitting” and is one of my favourite new year jobs – laying the little tubers out, eyes upright, in a light, cool but frost-free place at about 10C (50F).
I put half my seed potatoes for chitting in the porch by the window and half in the greenhouse. A garage or porch, slightly warmed by the house, is ideal for chitting potatoes. Light is important so don't shove them off to the back of a shed.
If you have only a few potato tubers, line them up in egg cartons. If you’re doing lots of chitting, put the seed potatoes in shallow, open boxes, like the slatted-bottomed ones you get at the greengrocers. Divide this up with sections of folded newspaper to keep the tubers upright and slot them into that.
There is great debate about the necessity of chitting potatoes, but in our comparisons at Perch Hill, it does seem to ensure a quicker and slightly larger harvest. With early varieties it gets them off to a flying start, so we can begin the harvest by the end of June and we now do it for blight prone main crop potatoes such as the very tasty 'Pink Fir Apple’. It makes them grow faster and form larger potato tubers once planted out, so we can get a crop of potatoes in August or early September, before the worst of the blight takes hold.
Keep an eye on your potatoes whilst they chit and wait for strong, short green shoots to appear (4-6 weeks) about 2-3cms long from the eyes of each tuber. You don’t want the white, spaghetti-like things you get when potatoes are kept in the dark in a cupboard, but stout green and pink things.
If you want to maximize the size of your potatoes, rub off all but three or four of the shoots at the top end of the tuber before planting out. If you leave all the shoots intact, you’ll end up with lots of small potatoes - it’s up to you.
Once your potatoes are chitted, it is time to get them outside into the ground, or in a container. Potatoes are divided into first early, second early and maincrop varieties, depending on when they are planted and are ready to harvest.
Plant earlies in mid-March in the south, a few weeks later in the north. They need to be planted 12-15cm deep, spacing them at 30cm between each potato along the row with 60cm between the rows. As the leaves emerge, using a rake, cover with soil along the row, this protects the young leaves from frost.
For maincrop potatoes, plant them about a month later, in April or even May to get a good cropping succession after the earlies. The same planting advice applies with maincrops as for earlies - except for the planting distances along the rows. Maincrop potatoes make bigger plants, so plant the tubers 40cm apart with 75cm between the rows.
First earlies: ‘Sharpe’s Express’, ‘Winston’
Second earlies: ‘Charlotte’, ‘Kestrel’, ‘Nicola’
Maincrops: ‘Belle de Fontenay’, ‘International Kidney’, ‘Pink Fir Apple’, ‘Ratte’
how to care for potatoes
If you grow potatoes in the garden soil, only water when the weather is really dry. Potatoes tend to find enough water in the ground as they root so deeply. If they are in a container or in the greenhouse you will need to water your potatoes when the compost starts to dry out.
Potatoes do need plenty of water to get a high yield, but if it is taste you are after do not over water, as this can make the tubers rather bland.
When the plants are about 10cm high they need proper ‘earthing up’. This means piling the soil from around the plant up over the plants to form a ridge along the row, to stop the tubers that are near the surface from going green in the sun. Some people like to use grass clippings or homemade garden compost to earth up their potatoes, this also ensures the soil is extra fertile and will retain more moisture.
Harvest the earlies when the flowers have opened, or the buds have dropped off. This will be in June/July. For maincrop varieties, lift the potatoes only when the foliage starts to die down, but make sure all the tubers are lifted before the onset of frost.
Make sure you pick up every potato, however small, this will avoid too many ‘volunteers’ returning next year to mess up your rotation and spread disease. If you have a large supply of maincrop potatoes these will keep through the winter if you have a cool and dark but frost free place to store them.
growing potatoes in bags
Potatoes can also be planted in bags in late summer and, if kept frost free, will produce a crop for Christmas. In August, plant two tubers in an inside-out compost bag or potato planter without bothering to chit. I tend to use 'Charlotte' for a Christmas crop.
Roll down the sides of the bags to about half their height, make a few holes in the bottom of the plastic for drainage and fill the bag to a depth of about 30cm. Use one third soil-based compost, such as John Innes No. 3, and two thirds compost.
You can also substitute your soil-based compost with earth from molehills, if available. Earth from molehills will give you lovely crumbly loam where the moles have done the hard work for you. They create the most friable grass-free soil from a depth usually below the worst of the weed seed. Avoid using mushroom compost with potatoes as the lime in it promotes the proliferation of scab.
Put in two tubers per bag and bury them in the 30cm of soil/compost mix and back fill another 15cms or so on top. Water them in well. Put your sacks somewhere bright, frost free and a little warm.
Within 3 weeks or so, they will have begun to shoot. Keep the compost damp, but not sopping wet. Once the shoots are about 15cm, roll up the edges of the bag a few turns and fill up to that level with more soil/compost mix.
Carry on earthing them up, bit by bit every couple of weeks, until they reach nearly the top of the bag. Allow the shoots to come up to flower and you can start to harvest, usually by the end of November.
harvesting potatoes grown in bags
We find that the flavour of the potatoes is better when potatoes are harvested and eaten straight away, rather than stored. When stored, some of the sugars in the tubers convert to starch and the flavour gradually disappears. For this reason, it's worth perfecting your potato milking technique: cut off a corner of the bag and put your hand in from the bottom. Harvest and eat only what you need for that meal. You can then water from above and if you have not disrupted the root system too much, it should continue to grow.
If you have several people to feed at once, you can turn out a whole bag at a time, it's easiest to do this into an empty wheelbarrow.
It is a good idea to force some potatoes to give you an early crop to eat in May and June before the outdoor grown crop is ready. To force potatoes, plant tubers in an inside out compost bag or a potato planter in the greenhouse in February or March. I use ‘International Kidney’ and ‘Belle de Fontenay’ for forcing. Follow the instructions for growing potatoes in bags above and they should be ready to harvest in May and June.
- January – March: set your seed potatoes out to chit.
- February: plant tubers in containers to force in a greenhouse.
- Late March: plant early potatoes outside
- April: plant maincrop potatoes outside, earth up as leaves begin to emerge.
- May: continue to earth up to prevent greening of tubers
- June: start harvesting forced potatoes.
- July: start harvesting early potatoes
- September – November: Harvest maincrop potatoes.
- Order your seed potatoes for the following year.
pests, diseases & common issues
The little black keel slugs are perhaps the worst pests to attack potatoes, as they do not go for the foliage, they wait until the new tubers start to form and burrow inside your perfect potatoes, only appearing when you cut them in half. Growing earlies will help avoid this as they are in the ground for a much shorter period, and growing in bags or containers usually ensures the slugs don’t get much of a chance. Rotating the position of potatoes in the garden each year is also important, as it avoids a buildup of all pests.
eelworms & wireworms
Eelworms and wireworms burrow into potato tubers and can prove a nasty surprise on the plate. There is an organic solution which is to sow a catch crop of mustard as a salad crop or green manure after or before growing your potatoes – this acts as a biofumigant and helps control these pests (as well as improving your soil).
potato wilt disease
Wilting caused by the fungus Verticillium is rare in UK gardens, as our winters are generally cold enough to kill off the spores. Being soil born, frequent rotation is a good practice to follow.
A warm wet summer is exactly what Phytophthera infestans loves, so keep an eye open for black spots on the leaves and stems and remove before they can infect the tubers. With maincrop potatoes it is often best to remove all the foliage if you get an attack, and dispose of the leaves away from the vegetable garden.
common potato scab disease
Usually the scabs on potatoes are superficial and can be scraped off before cooking. They can be caused by the soil being too alkaline, so do not lime the ground before planting potatoes.
potato wart disease
Potato wart disease is caused by a fungus, and can be very serious. Thankfully our strict controls on selling only certified seed potatoes means that it has been eradicated in the UK.
blackleg potato disease
A bacterium on infected tubers is responsible for the occasional collapse of whole plants from the root up, early in the season. Remove the whole plant and destroy and this should stop it spreading.
why do potato plant leaves turn yellow?
If the yellowing is between the veins then this is usually due to a magnesium deficiency in the plant. A short-term cure is a foliar spray of Epsom Salts, but next year, make sure that soil has plenty of organic matter as this allows plants to absorb more minerals naturally.
how do I protect my potato plants?
Potatoes are particularly susceptible to cold, so if a late frost is forecast and the foliage is above ground, earth them up quickly with surrounding soil. If the leaves do get frosted the plant will recover although it will be set back by a few weeks until new shoots can come up from the tuber. Some people use horticultural fleece as a preventative, and this can offer some protection against a light frost.
frequently asked questions
how far apart should I plant potatoes?
This does depend on the variety. Earlies can be planted more closely together (30cm apart, 60cm between the rows). Maincrop potatoes need more space (40cm apart, 75cm between the rows).
how many potatoes will I get per plant?
Again this depends on the variety – ‘Ratte’ will give you loads of small potatoes, whilst ‘Winston’ will give you 6 or 7 nice large baking potatoes. You can also encourage larger potatoes by rubbing off some of the “eyes” before you plant.
what do I do if my potatoes don't flower?
Don’t worry about it, the flowers are not important to create the tubers, just as a gauge of when they might be ready to eat. So if you are unsure, just scrape a bit of soil back and see if the potatoes look big enough to eat.
should I cut the tops off my potato plant?
Only if you suspect that there is a disease affecting the plant. The longer the leaves persist the greater will be your crop as they are busy storing energy in their tubers for the winter.
do potatoes keep growing after the plant dies?
Once the leaves die back they will stop growing but they will start to shoot again once the spring comes if they are left in the ground.
what happens if you don't harvest potatoes?
They will sit in the ground waiting to sprout again in the spring. These are often called “volunteers”, but sadly they tend to come up where you don’t want them, especially if you are rotating your vegetable patch. Best to dig them up and start with fresh disease-free seed potatoes.
why earth up potatoes?
This will protect them from the frost when they first emerge from the ground. Later on it will also protect the forming tubers from the sun which would otherwise turn them green and inedible. It also helps retain the moisture around the roots, especially if you earth up with garden compost or grass clippings.
when to harvest maincrop potatoes?
To get the biggest crop you should really wait for the foliage to die down. However, if you suffer from slugs or blight it is better to take a small reduction in yield to avoid pests and diseases if the tubers are left in too long. It is possible to scrape some soil back from the mound, remove a few then cover up again for the rest to grow on. They must all be harvested before the frost sets in.