18 July 2018

Taking root: Potato season at Kew's Kitchen Garden

It’s July in the Kitchen Garden at Kew and potato season is well underway. From helping the war effort to being the first crop grown in space, there’s more to the humble spud than meets the eye.

By Héléna Dove and Ellen McHale

Kitchen Garden

What is a potato? 

Potatoes are part of the nightshade family (the same family as peppers and tomatoes). 

Potatoes are tubers. Tubers are the storage organs of a plant. The plant uses them to store nutrients and water, to help them regrow in the next season. 

So when you're crunching crisps or munching mash, you’re actually eating the stored energy of a potato plant. 

Not always a staple 

The humble spud… boiled, fried, roasted or mashed, there isn’t a plate in England that hasn’t enjoyed the yummiest of carbs. 

But when they first arrived in Europe in the 1560s, they were treated with suspicion. Their flower looks very similar to the poisonous flowers of the night shade (Atropa belladonna), as both plants belong to the Solanaceae family. 

They were mainly used as animal food. In northern Europe, they were grown in botanical gardens as an exotic novelty. 

However, potatoes soon took root. They became everyday staples during the Industrial Revolution in the 19th Century, as they were a cheap source of calories and nutrients.

Potatoes being dug up
Potatoes, Ellen McHale/RBG Kew

Packed with the good stuff 

Potatoes are a good source of fibre and they also provide potassium, Vitamin C and Vitamin B6. 

One medium potato actually has more potassium than a banana.   

Potassium is important for health.  It helps your muscles contract, regulates the fluids in your body, and can improve blood pressure. 

Potato facts 

  • There are over 100 different types of potato.   
  • Potatoes originated from South America, specifically in the Andean mountain region. They were later on introduced to Europeans by Spanish explorers in the 16th century.    
  • Potatoes are 80% water, 20% solids.
  • In 1995 the white potato became the first crop to be grown in outer space, by astronauts aboard the Space Shuttle Columbia.   
  • Pringles made the world's largest crisp in 1990. It measured 58 cm in diameter.  
  • The heaviest potato ever grown weighed 4.98kg. It was grown in 2011, by an amateur gardener in his back garden in Nottinghamshire.

                                                             

Potatoes being dug up
Potatoes, Ellen McHale/RBG Kew

Spuds at Kew 

Potatoes have long been grown at Kew and in 1918 the Palace Lawn was ploughed to plant potatoes, harvesting twenty-seven tonnes in August 1918 to help the war effort. 

During World War Two, the curator of the gardens William Campbell discovered that potatoes could be grown from sliced potatoes as long as they contained an ‘eye’. 

Potato ‘eyes’ are the indentations you see on the skin of the potato, which is the start of the potato trying to sprout roots. It’s from these sprouts that new potatoes grow when planted. 

Potato cuttings at Kew during ww2
Potato cuttings at Kew, RBG Kew

Kew's potatoes today 

This year we’re growing a mixture of heritage potatoes, including the Pink Fir Apple which dates from 1850, to the Lady Christl which was bred in 1996 in the Netherlands. 

We classify our potatoes as first earlies, second earlies and maincrop, and this division is down to the length of time they take to produce a harvest. 

First earlies take around 12 weeks to produce a crop. We’ve harvested most of these already, and now we’re digging up our second earlies which take around 13-16 weeks to grow. 

Potatoes grow in any soils but will thrive in looser soils, where they can grow bigger with no resistance. 

They're a hungry crop, so the soil needs feeding. I add a layer of compost to the beds in Autumn, then line the trenches with comfrey leaves when planting for extra fertility. I also apply comfrey liquid feed whilst they’re growing to give them a boost, which I make at Kew. 

Potatoes enjoy a cool climate as this reduces fungal diseases such as blight, which thrives in humid environments. This is why a lot of seed potato is grown in Scotland. 

The perfect potato salad 

Both first and second earlies have thin skins and waxy flesh, and don’t store well. 

This makes them perfect for boiling and eating as salad potatoes. They hold their shape well, which is the key to a good potato salad.   

Treat yourself to this deliciously different potato salad recipe with gherkins, capers and peppers from Kew's Global Kitchen Cookbook. 

Ingredients 

  • 750g (1lb 8oz) waxy salad potatoes 

  • 3 sour pickled gherkins roughly chopped 

  • 3 sun-dried tomatoes in oil, cut in strips 

  • 15ml (1 tbsp) capers, roughly chopped 

  • 1/2 sweet green pepper diced 

  • 1 onion, chopped 

  • small bunch chives, snipped 

  • basil leaves, snipped 

  • (optional: dry salami, diced) 

For the vinaigrette: 

  • 60ml (21/2fl oz) good olive oil 

  • 15ml (1 tbsp) cider (or wine)vinegar 

  • 1 clove garlic, finely chopped 

  • 5ml (1 tsp) grainy mustard 

  • a pinch of sugar, salt and pepper

Directions 

  1. Boil the potatoes in their skins for about 20 mins, or until cooked. While they are cooking, prepare the vinaigrette - put all the ingredients into a small jar and shake.  
  2. When the potatoes are done, drain and put into a large bowl with the vinaigrette. If they are large, you might want to slice them. Turn the potatoes gently to keep them coated. 
  3. As they cool, prepare the other ingredients and add them to the salad one at a time, mixing in gently. Allow the salad to stand for a while, but serve it still warm, rather than from the fridge. This kind of salad is often better on the second day. Again, don't eat it straight from the fridge. 

Find more inspiring recipes from Kew’s Global Kitchen Cookbook. Or come and visit our Kitchen Garden to find out what else we have in store. 

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