The potato plant is a member of the Solanaceae family which includes tomatoes and peppers. There are many cultivated species of solanum tuberosum.
The potato is a cool loving plant, found wild in South America on and beneath the snowline. It came to the UK in the late 1590’s via The Spanish (not Sir Walter Raleigh!) and gradually became acclimatized to the British weather.
Its leaves are poisonous and the potatoes (otherwise known as tubers) turn green and develop glycoalakaloids if left exposed to light. No commercially grown variety can resist frost and the plant will not grow effectively above 28c. The plant will appear elongated if grown in shade and be more prone to the disease Potato Blight. More of that later!
Which Variety Do You Want To Grow?
So let’s think about what kind of potato you want to grow and the space it will need. Do you like new potatoes that have flaky skins which you eat in the Summer months or do you like potatoes you can harvest and eat at your leisure, be it baked, roasted, mashed etc.? It all depends on personal preference…but hang on - there are so many varieties! Take a look at this website and also The Peoples Potatoes book for more details on potato varieties.
At The Whitchurch Organic Gardeners Potato Show this year we had around 140 potato varieties with hundreds more in The Scottish Reference Collection (2000). Feel free to have a chat with people at these types of shows as you can really learn more about different potato varieties. However, one main tip when choosing a potato variety is to avoid some of the newer introductions seen in supermarkets. They are bred for intensive and precise farming which we in the gardens will find hard to replicate.
Think about where you are going to grow the potatoes and the time you will have to look after them. This will be a hint as to what varieties are best for you. Some varieties, such as the coloured flesh types or dark skinned ones lend themselves to bags or buckets so we can find them easily. Bags are also good for small areas or people who are not into digging (it’s hard work after all!) The good news is that there are enough potato varieties to best suit all types of growing styles!
You should also ask yourself if your chosen area will be easy to water and whether there is water available as this will affect which potato variety you should choose as well.
Growth Types & The Seed Potato
Each variety is classified into three key growth types:
• First Early
• Second Early
• Main Crop
Sometimes we may see the term Early Main Crop or Late Main Crop. These terms relate directly to the speed of growth and development of tubers. So our new potatoes harvested in June or July will probably be from First Earlies as they mature the quickest. But don’t get hung up on this as it’s only a guide and you can, for example, eat the Main Crop variety King Edward when the skins are flaky and enjoy it as a new potato and as it develops. The variety Maris Peer, the mainstay of supermarket UK new potatoes is, in fact, a Second Early. Red Duke of York is a First Early that is best enjoyed as a baker throughout the Winter if you like that kind of thing. Remember that as the each variety grows the tubers develop in texture. Many varieties start off waxy and become less so, even dry. That my friend is the world of potato varieties!
The term ‘seed potato’ simply refers to a potato from last years crop that a person has set aside for harvesting and then planting the following season. However, it’s more complex than that; in fact a whole industry in Scotland and the EU functions to produce seed potatoes that are as free as possible from disease. Aphids carry viruses that really damage crops so that is why we buy fresh seed potatoes that have been inspected and quality assured to be the best. You can keep your own seed but as time goes by the risk increases.
Buy your seed potatoes early. As soon as Christmas is over they arrive at the garden centres and get onto the shelves. If you buy later e.g. around March, the heated shops and darkened isles will have encouraged thin (easy to break) white sprouts which we don’t want to see. The tubers may also appear dehydrated. The best size is that of hen’s egg. The tubers should be free from any wetness or rots. Remember if it’s certified seed then it will say so.
Once home, the seed potatoes need to be placed into a seed tray or shallow box. The tubers should sand with the rose end. This is the opposite end to where the potato was joined to the plant. Keep in a frost free cool light place where the eyes of the tuber (shallow or not so shallow indentation) can open and set forth slow growth of a sprout. We want all the eyes, or as many as possible, to open together as it’s from the eyes that stem growth will come and it’s the stems that ensure the first part of yield potential. No stems = no yield!
The seed tuber is the source of the growth with the eyes of the potato (indented parts) giving sprouts which then, upon planting, put out roots at the bottom and stems with leaves above ground. The stems are key to yield and one seed tuber the size of a hen’s egg should ideally produce five or more stems.
Now we need to understand the growing requirements a bit better and in our next module we will think about soils and material used for growing potatoes. See you in Module 2!