Potatoes - Solanum tuberosums
Buying to Grow|History|Chitting|Nutrition|Diets|Planting out|Cultivation| Potato Fruits|Harvesting|Common Problems|Varieties|Clamp and Other Storage Methods (new page)
Potatoes are a wonderful crop for the first timer and much loved by many vegetable gardeners. If it is your first year on your plot then I recommend growing growing a few plants, the soil gets turned over when you dig them up in preparation for the next crop and they are also relatively easy to grow. Please use the links above to find out what you need to know about growing this staple crop.
Potato History
Potatoes ( Solanum tuberosum ) are native to the high altitudes of the Andes Mountains and have been cultivated in Chile from at least 5000BC. Wild potatoes still grow all over South America and are eaten by the locals who give them the name papas criollas . It is the natural selection and interbreeding of these wild potatoes that gave us the more regular shaped tuber we know today.
Potatoes and Sir Walter Raleigh
It is often believed that Sir Walter Raleigh was the first to introduce the potato to Europe. It appears however this is only part of the story. Sir Walter never set foot on the North American shores and only instructed, ran and organised various landing parties and colonies. One of these colonies in Virginia (Now North Carolina) fell into difficulties and the survivors had to be rescued by Sir Francis Drake on his return from battling with the Spaniards in the Caribbean. On the way Drake had stopped in Cartagena (Columbia) to take on supplies including many native South American plants including some potato tubers and tobacco.
The Raleigh link comes about, as it was his second in command of the settlement Thomas Hariot who had potatoes included with some of the botanical specimens he had found in Virginia. It was also thought that Hariot planted one of these tuberous specimens in Raleigh's estate in Ireland.
However other reports also claim that is was the Spanish themselves who introduced the potato directly from Cartagena to Spain.
Slow Introduction into Europe
It took a while after these events for the potato to become established and accepted by the Europeans. All over Ireland and the UK many Protestants would not plant potatoes, as they had no mention in the Bible. Catholics would grow them, only however, if their seed potatoes were sprinkled with holy water and planted on a Good Friday.
Another account claims that Count Rumford (a famous American scientist and explorer) when in the service of a Bavarian workhouse would have to boil potatoes behind a screen until they were a mush so the inmates would not reject the gruel.
The Potatoes' Acceptance
In Prussia Frederick the Great sent a load of potatoes to staving peasants in Kolberg who refused to eat them. Frederick did not accept this and later sent an armed soldier who eventually convinced the people of Kolberg of the potatoes virtues.
A man called Parmentier, after being fed potatoes in a German prison in the Seven Years War, convinced Louis XVI of their delights. This was to such great effect that Louis convinced his wife to wear potato flowers around his court.
The potatoes' popularity continued to rise throughout Europe. It became an important crop in wartime as it grew underground it could not be destroyed by pillaging armies.
In the Second World War in Britain it became an important staple of the British diet as it was easy to grow and very versatile.
Potato Nutrition
Potatoes have long been a staple food in the British and Irish diets and provide 20% of Britain's vitamin C intake. They also contain protein, potassium, B vitamins (thiamine, riboflavin, and niacin) and of course have a high percentage of starch.
Diets and the Potato
It is this starch that has caused the poor old potato's popularity to suffer recently with the rise of fad diets such as the Atkins and South Beach diets. As potatoes are quite starchy and shunned by Atkins dieters who try to avoid carbohydrates in any form. Also when cooked this starch is readily digested by the body giving a sudden rise in blood glucose and therefore avoided by those on the South Beach diet who aim to eat food with a slow release of glucose, (or low Glycemic Index/Low GI foods).
However this is not to say that people on the South Beach Diet should never eat a potato again. New potatoes have a moderate Glycemic Index (GI) so those on the South Beach diet (also low GI dieters or Diabetics) can substitute old potatoes for new. New potatoes are also have a higher level of vitamin C than Old potatoes.
Despite their high glycemic index potatoes are an excellent diet food as they are cheap and easy to prepare and relatively low in calories, a 200g portion will supply just 140 kcal. The idea that much of the potatoes' goodness is in its skin is partly true. Cooking a potato in its jacket will cause fewer nutrients to leach out than boiling and the skins contain an amount of dietary fibre. However unless home grown or organic potatoes should be thoroughly washed as agrochemicals can build up in the skins.
Growing Potatoes
What to buy
You don't have to go out and buy an expensive bag of growing potatoes, although this year I did to try them out. I have grown a crop of supermarket bought potatoes and a grown a crop of growing potatoes, planted them at the same time as each other and guess what? Similar results for both. I would not say one has faired better than the other as they have grown at exactly the same time.
The reason that seed potatoes are sold is because they are grown at high altitudes to cut down any chance of disease carrying spuds. There are less insects at high altitudes and so this means less disease. It is Ok to use shop bought potatoes in the first year but if you store them and use them for the second year the chance of them carrying disease is far greater than it would be if you used second year seed potatoes.
Potato Chitting
No its not a swear word, chitting basically means gettinggreen shoots coming from your potatoes ready for planting out, see image on the left, this is how they should look, not like the image on the right. (the long and spindly one)
The conditions were slightly different for the two, in short the bottom one did not get any light, the same can happen if the they are too warm. I placed mine on my kitchen window sill in an egg box for a few weeks, just slightly out 
of the direct sunlight and they chitted fine. Ideally you should let the green shoots grow to be about 1.5 - 3 cm (1/2-1inch) tall.
Planting out
Potatoes are the best crop to grow on newly broken grassland or wasteland, earthing up and the dense leaf canopy help clean up land. Potatoes should not really be grown on a plot that has had potatoes on it in the previous two years. They can be grown in most soil types, for example I have quite clay full land and mine have flourished, not only that I am told that they will help break up the clay.
Potatoes should be planted out after the danger of frost has gone, usually early April in the UK. They should be planted at about 10-12.5cm down (5 Inches) and 30-37cm (12-15 inches) apart with 60-70cm (24-30 inches) between each row.
Ideally when planting the holes that you plant them in (also known as drills) should be lined then filled with sieved manure, compost or peat.
Cultivation
Not much to do with potatoes really, they are half hardy so the young growths will need protection from frosts either draw up some soil around them or put some straw on them, removing the straw at a later date to ensure that they don't go moldy.
Water in dry weather, especially when the tubers have started to grow.
The only other thing to do is to earth up, there are different schools of thought here, but I think that its fine to earth up in one go rather than gradually. Earthing up means to move soil around the base of the plants to protect them, this is done when the plants are about 22cm (9 Inches) tall. Break up the soil between the rows with a fork and remove all the weeds, then bring it up around the plant in a tent like shape up to about 15cm (6 Inches).
Harvesting
For new potatoes wait until the flowers have dropped off, I wait about a week after but it depends on the variety. You can sneak a peak by carefully forking back the soil with a small hand fork, but be very careful I have destroyed part of a plant by doing this, I think I disturbed the root. Once ready though stick your fork in and lift out the potatoes into the trench. Ensure that you do get all of the potatoes out when lifting them as you could end up leaving a nasty disease in your soil.
Anything you dig up after this will be known as second earlies, and until the leaves go brown and wither your potatoes will still be growing.
To harvest potatoes for growing next year, wait until they have stopped growing. Cut off the top plants and wait for about 2 weeks. Lift the roots out and let the potatoes dry for several hours. Place in a dry wooden box or a potato clamp (link to making a potato clamp), ensuring they stay frost free and you should be able to use them next spring.
Potato Fruits 
A very strange occurrence happened to my potatoes this year, after they had flowered little tomato type things were growing on them.(see the picture above) I did a bit of research and found that they were potato fruits, this is where the seeds grow. This was news to me as I thought that all potatoes were grown from chitted potatoes. Apparently I could have the possibility of having cross bred potatoes. This is because of cross pollination as I grew two different varieties, maris Piper and King Edward I could have a new breed. It will be interesting to kind out what colour they grow into. Each of the fruits can contain up to 300 true seeds, and every seed will be genetically different.
Apparently you can separate the seeds out of them by putting them in a blender on a slow speed with some water. Then leaving them in water for a day so that the seeds will sink and the rest of the fruit will float. However, I do not have a blender so I will have to separate them by hand.
I shall plant them out next year and make a careful note of the strongest plants so that I can use the fruits again the year after and only keep the strongest plants.
A word of warning though, do not eat the fruits as they are poisonous. Remember that potatoes are in the same family as deadly nightshade!
Potato Varieties
I was going to do a section on the varieties of potatoes here but after a bit more careful research I have realised that there are loads of varieties. So, rather than have a huge section I have just found some links to help you choose which potato is best for your climate.
A list of spuds and their countries and what they are resistant to. (mostly europe)
A site with links to potato varieties For most of the world
Potato problems
Seed potatoes can either end up like this (click to enlarge), as I said earlier and this is due to keeping them in a place that is too dark or too warm. If they are kept in optimum conditions and still yield spindly sprouts, then they are probably diseased and need to be chucked, it could also be that they have been caught by a slight frost. The other problem with seed potatoes is getting no sprouts at all, this could be due to a disease or again frost whilst in storage.
If the leaves are full of holes or have tiny brown spots on them then this could be due to the Capsid bug, should not effect the yield unless the attack is severe.
Pale green or yellow leaves could just be drought and can be sorted out with more watering. It could also be aphids which can be gotten rid of by introducing predators such as ladybirds (Ladybugs U.S.) or by giving the plant a garlic spray made with highly concentrated garlic or with a treatment of neem oil. Your plant could also be suffering from blackleg, this happens early on and will be accompanied by blackened stems. I can't find a treatment and it is recommended that you should lift and burn the affected plants. To prevent black leg don't plant sort or rotten potatoes. Lastly pale green or yellow leaves could be due to potato cyst eelworm, also characterised by pinhead sized cysts on the roots. Panic if you get this and again destroy all that are infected to try and stop it spreading. Don't grow a susceptible variety in the same spot and use a variety that is resistant. Proper crop rotation will help in prevention also.
Brown patches on the leaves is another panic situation, as this could be Potato blight, perhaps the most famous of potato diseases due to the famine in Ireland. It's prevention rather than cure I'm afraid, always plant healthy chitted potatoes. Spray the unaffected plants with liquid copper, an organic, flowable fungicide. A special formulation of copper salts for control of fungal diseases of vegetable, fruit, and ornamental crops.
There are many more problems with potatoes but if you have had trouble in the past and find it difficult to grow potatoes I highly recommend shopping around for resistant varieties.
The Vegetable and herb expert that I have referenced below contains more detailed descriptions of many more potato problems, however it is not too good on giving treatments or organic preventions. I have found a site that seems to only promote its own products but does give organic solutions to many potato problems, a click here.
By Andy & Dave Hamilton