Tips for increasing potato yields

When at potato day at the end of January, I picked up Alan Wilson's new book, The People's Potatoes. I've already written about the engaging talk he gave on 20 Challenges and Opportunities for Potatoes, which he also talks about in the book. The first half of the book includes interesting chapters that cover topics from understanding the biology and growth of potatoes, the production of seed potatoes, chapters on both commercial and home/allotment potato growing, and one on pests and diseases. The second half of the book goes on to detail Alan's top 100 potatoes, then a reference section covering a further 300 potatoes also grown in the UK.

It's great to have the reference section and detailed listing of so many potatoes as it is not easy to get this information in books generally, or even by searching the web. I can see that I'll be referring to this section regularly to get more information about the potatoes I grow, or might grow in the future.

The book also contains some wonderful tips for growing potatoes and increasing yields. It goes beyond general advice you usually get, such as remembering to earth up your potatoes and when to dig them up. Below is a summary of some of the key points (in my opinion) from the book that should help increase your potato yields.

1. The most productive potato plants are those produce a good leaf canopy, and the longer the leaves remain, the higher the potato yield. I found this interesting as we are often told you shouldn't feed potatoes nitrogen as it will just encourage leafy growth at the detriment of the potatoes in the ground. BUT, as the book says, a good leaf canopy means there is more area to intercept light, which via photosynthesis is turned into energy for the plant. This helps it develop good roots systems that extract the water and nutrients needed to increase yields.

2. Stem numbers are key. That is, the more stems that come direct from the ground and form a leaf canopy, the higher the yield. Stems that grow direct from the seed potato you planted are 'main stems' and these usually produce tubers. So the more main stems, the more tubers. Stems that branch off from the main stem are 'secondary stems' and these don't usually produce tubers unless the branching point is close to the seed potato. That is, the branching out happens quite low down at the base of the plant.

3. Watering. The key growth stage for potatoes is usually 3-4 weeks after a plant has first emerged from the ground. The plant sets tubers at this early stage, so a lack of water or soil moisture at this point will effect the yield. Potatoes of course need watering throughout their growth cycle, particularly in hot weather if you are to maintain yields. But it's particularly important that they are well watered at this point if you want your potatoes to set more tubers. And don't forget that the more organic matter your soil has, the more moisture and therefore the better chance of increased yields.

4. Foliage die back. When the foliage starts to die back, the plant is coming to the end of its life cycle. But where the foliage starts to die back is very important. If the dying back starts at the base of the plant and moves up the leaf canopy, you should have healthy tubers. However, if the lower leaves are healthy but the upper leaves are turning yellow, it may be the plant is suffering an attack from a pest or disease, or lacking nutrition.

5. Digging up. Don't start digging up all the tubers as soon as foliage starts dying, unless you intend on eating them all fresh! As the plants die back, tubers start to form a skin, called setting a skin. This helps the tubers to develop a protective layer, which is particularly important if you want to store your potatoes for any length of time. You need to allow 2-4 weeks from when die back begins before digging up the crop that you intend on storing. Allowing the tubers to set their skin helps prevent water loss, stops tubers from going soft, and reduces the risk of disease. So, for fresh earlies, harvest whilst the leaves are still green. To store, wait for the skin to set.

6. Inside the potato. Generally, though not always, lower dry matter (i.e. less than 20% starch) is typical of earlies, and usually (but not always) produces smooth waxy potatoes that are good for salads. Potatoes with a higher dry matter content (more than 22% starch), produce more floury roast/baking potatoes. For boiling potatoes, avoid using high dry matter varieties. Or if you do boil them, do so for less time, so they don't break up.

The book goes into more detail than I have here, but hopefully it gives an indication of it's usefulness. I learned a lot of new things about how to grow potatoes, and also the reasons why you should do things a particular way.

I recommend this book to anyone who enjoys growing and eating potatoes. It's intelligent and engaging, and I expect my yields will be increasing this year. And that makes for a happy belly.

Garden visit: Anglesea Abbey (2nd visit)

The winter walk includes many trees and shrubs that
give wonderful winter colour:

hamamelis, cornus, viburnum, betula and prunus

Anglesea Abbey is well known as one of the best winter gardens in England. I've visited before and I'll visit again. This years visit, yesterday, was as lovely as always. It has to be said that the sudden freeze had meant that the poor snowdrops have been hit, and whilst they were flowering, quite a lot were laid low by the cold weather. But there is so much to enjoy in the winter garden and by the Lode mill, that you don't just go for the snowdrops. My visit in pictures...

hamamelis, with cornus behind

The lovely bark of Acer griseum

Galanthus 'Ophelia'

Galanthus 'Merlin'

Galantus 'Galatea'

The beautiful shiny bark of Prunus Serrula

Birch grove, betula jacquemontii

Canal by the Lode Mill

Reflections of the Poplars in the ice

Young Miguel cannot resist testing the icy canal, with parents Patrick and Lyn 

L-R: Audrey, Lyn, Patrick, moi, Kevin

First day of the month in the front garden: February 2012

Ok, slight cheat - it's the 2nd day of the month. Does the fact I did my back in yesterday give me any grace?

Front garden, 1st (ok, 2nd) February, 2012

Early February in the front garden. After January being so mild for most of it, the sudden cold has slowed things down a bit. However, compared to the greyness of January's post, the lovely colours of a cold and sunny February makes it worth it.

Broad beans coming up

Not a lot has changed, other than the broad beans I planted in the right side bed have sprouted where there were nowhere to be seen in January.

Bulb and iris leaves

I also have the leaves of various bulbs coming up, muscari and crocus, as well as some of the garlic. And the Iris leaves, which never completely died off this winter (unlike the previous year), are standing to attention and getting read to put on exponential growth the moment it gets warmer.

The first colour has arrived in the guise of one lonely crocus flower. Not even open, thanks to the freezing temperatures of the last few days. But that just makes it more welcome, more of a delight. Despite the weather it's keen to get outside and do its thing.

Now we wait to see if February remains cold and therefore growth is slow. Or will it suddenly warm and bring out not just the crocus but all the daffidol and narcissus flowers, but also the green growth of the fritillaries?

20 Challenges and Opportunities for Potatoes

Another benefit to attending Potato Day is the talks by specialists that are run throughout the day. I attended the '20 challenges and opportunities for potatoes' by Alan Wilson. It was a really interesting talk, and I learned quite a bit I didn't know about potato growing in the UK, including some surprising facts. Here is a brief overview of the 20 challenges/opportunities Alan presented.

1. Decline of fresh potatoes: apparently in 1998 (UK) 71.8% of potatoes eaten were fresh, i.e. whether home grown or from supermarkets, with the remaining percentage being consumed as processed potatoes, i.e. hot or frozen chips. In 2010 only 38.9% of potatoes are consumed fresh. That's a massive decrease and says a lot about our relationship with food, as well as the impacts on our health.

2. Pasta vs. Potato: following on from point 1, we are also eating much more pasta and rice as a staple, instead of potatoes.With pressures on peoples time, these are perceived as being clean, easier and quicker to cook.

3. Value of food crop: you can eat less potatoes per meal to gain the same value in nutrition (see 4. below), compared to what you would need when eating pasta. Also, the amount of land needed to grow potatoes is much less than you need to gain the equivalent value from cereals.

4. Nutrition: potatoes are very nutritious and contain a lot of vitamin C. In the past, potatoes gave people their winter access to vitamin C, whereas now you can by orange juice etc all year round. They are also a good source of vitamin B6 and potassium and have no cholesterol. (The Potato Council has a useful page listing the healthy qualities of potatoes.) Furthermore, they are quite low in calories too.

5. Gardeners: gardeners have quite a few challenges in order to grow potatoes. From the lack of allotments available to the smaller size of gardens that come with new housing. However, gardeners are also the champions of potatoes, potatoes are very popular with gardners and they grow lots of different varieties which is good for diversity and food security.

6. Organic vs. Non-Organic: there is lots of debate over 'what is organic', but what is certain is that organic methods such as careful rotation and diversity in crops is the way forward and conventional growing needs to use organic principles if we are to maintain the crop.

7. GM: will it really solve the world's food problems? The irony is that GM claims to be 'blight resistant' yet there are lots of non-GM potatoes that already have this important feature. And we need to fix bad farming (i.e. monocultures), which GM won't do.

8. Water: a lot of pressure on this resource and it will get worse in future with the impacts of climate change. Potatoes need water, so growers need to be smarter about using this precious resource in the most effective and sustainable way.

9. Soil: the most important element. Fertiliser only goes so far, we need to build up the nutrients in our soil with compost and organic matter.

10. Biodiversity: unlike big farms, gardeners grow more than just one variety, use rotation methods and add nutrients to the soil via compost and green manures.

11. Nutrition for potatoes: whilst potatoes can get some nutrition from legumes (so a winter crop of green manures before planting potatoes the following spring has some use), water and potassium more important. Again, building the soil very important.

12. Wastage: gardeners consume 95% of their crop, the remaining 5% lost to pests (i.e. slugs), greening or a fork through them when digging up. 50% of crops are wasted by conventional farming. I'll say that again, 50%. So gardeners growing potatoes lowers the carbon footprint of agriculture.

13. Lifestyle: we only spend 8% of our disposable income on food. It was 25% in the 1950's. We have less time for growing and eating and are quite detached from our food system.

14. Perception and knowledge: people think potatoes are fattening - they are not! There is a perception that because they come from the soil, they are somehow dirty. Some even perceive potatoes as an old persons food. Clearly a lot of education is needed around people's knowledge of potatoes.

15. Varieties, pests and disease: more varieties are available with different levels of resistance to pests and diseases, yet only 1.5% of 21 old varieties* available are grown by industry.  *these are any varieties that go back more than 50 years.

16. Culinary knowledge: with 1400 varieties around, there is a lack of knowledge about how different potatoes have different culinary uses. TV chefs just use 'potatoes', not telling you what varieties they use.

17. Varieties: over 1400 varieties of potatoes available to the UK potato industry. Awareness of the different varieties available is increasing.

18. Quality: the importance of taste. Being aware that digging up potatoes at different times will change how they taste. For example, a salad potato (usually a 'new' potato) won't taste good as a salad potato if left in the ground too long.

19. Seasonality: we think of potato growing season as late March to October, but actually some varieties can be grown all year round (i.e. Rocket).

20. Values: the future of potatoes is in our hands. Do we value them as a crop? Do we understand they are good for you? Do we value what type of potato is grown for what culinary purpose?

I found many of these interesting and some shocking. Eating fresh potatoes is so normal to my circle of friends and I that it never occurred to me that a lot of people in the UK only eat processed potatoes. I was kind of aware that conventional farming throws away a lot of produce (because the supermarkets won't accept them), but 50% wastage is a bloody disgrace.

I have lots of other concerns about GM in general that Alan didn't raise. For example, who owns seed? I think seeds, including potato seeds, should be part of the global commons and not owned by multinationals for profit. And there is the health and environmental impacts of GM -  all those chemicals being sprayed onto GM crops cannot be healthy for neither people or the environment. This isn't a criticism of Alan (he only had 45 minutes and a lot to get through!), rather I want to remind people there are lots of questions about GM that should be considered.

As we are becoming more food aware, hopefully culinary knowledge of potatoes will develop. Some potatoes that are good for mashing are useless for boiling. And some that are good for roasting are bad mashers, etc. I choose the potatoes I grow very carefully to ensure that I have a range that cover the types of cooking I like. Hence in my list of pototoes, I included comments such as whether a particular potato was a good masher or salad potato, etc.

There was also a lot of hope in Alan's talk. Gardeners and communities are leading the way growing many varieties of potatoes (and other fruit and vegetables), which helps not only keep these different varieties available, but means that the gene pool for potatoes remains wide. Whether it is potatoes growing in different conditions (cooler or warmer environments for example), or for different qualities (bakers, mashers, salad potatoes), the fact that gardeners want and grow lots of varieties of potatoes, can only be a good thing for potatoes overall.

I purchased Alan's new book The People's Potatoes, which as well as giving useful information about growing potatoes, includes a synopsis of 400 varieties available in the UK. There is also a section with detailed information on his personal top 100. I've already started reading it and on first impression, it's a really useful reference for any potato grower and lover. For example, I knew about pests and diseases such as slugs, blight and scab, but from the book I also learned that aphids are a big problem for potatoes, as they are a key source for carrying diseases. And there is a useful bibliography with links and further reading at the back, which will be of use to those of us who are extra keen on learning more about growing potatoes.

For a 45-minute talk I learned quite a lot, and along with the other talks and cooking demonstrations (which I was unable to attend), it was another reason why going to Potato Day at Ryton is such a great experience. And yet another reason why I will return to Potato Day in 2013.  ;-)

Potato Day 2012

Happy at Potato Day

Recently described by friend Manishta as, "my version of Xmas", I went on my annual pilgrimage to Garden Organics 2012 Potato Day at Ryton. I love potatoes and I love going to Potato Day. Ryton generally has over 100 varieties from which to choose. This includes mainstream varieties such as Desiree and King Edwards (boring - they are in every supermarket so why grow them?) to heritage varieties such as Shetland Black and Salad Blue.

A few of the over 100 varieties available

As ever, I got excited on the drive up and walked very swiftly (I did NOT run) to the tent holding all the potatoes on arrival. I had a list of specific varieties I knew I wanted, plus room on the list for 'impluse choices' on the day. My final choices were:

Arran Victory (Late Maincrop. Heritage variety, good masher and yields)
Casablanca (2nd Early. Wonderful mash)
Charlotte (2nd Early. Great salad potato and for mash)
Pink Fir Apple (Late Maincrop. Such lovely salad potatoes)
Red Duke of York (1st Early. Excellent baker and storer)
Sante (Maincrop. Great for baked spuds)
Saxon (2nd early. New choice, I like the name..., meant to be good for baking, boiling and roasting )

I also order separately from JBA Seed Potatoes, as I knew they wouldn't be at Ryton:

Amour (my first time trying, meant to be an all rounder resistant to blight)
Ryecroft Purple (heritage, a good baker and roaster)
Stemster (Maincrop. v. reliable, high yielding, good baker and all rounder)

And I picked up for some friends who I'm encouraging to grow potatoes:

Casablanca (2nd Early. Wonderful mash)
Salad Blue (2nd Early. Heritage variety, for mashing and chipping, also an impulse by for me)
Shetland Black (2nd Early. Heritage variety, good for mash and boiling)

It's serious business choosing each potato

One of the great things about Potato Day at Ryton is that you can buy individual tubers. This means it is easy for gardeners to chose and try of lots of different potatoes. The diversity of sowing different crops also means that  if one variety is hit by pests and diseases, it's likely that the others may well survive. I've had occasions in the past where I've lost one crop to blight, but the potatoes right next to them weren't effected at all. Proving once again that diversity, and not monoculture, enhances food security.

Potato Day is quite social. I ran into Emma from Cultivate (above, choosing some Bambino seed potatoes), who is as mad on potatoes as I, as well as Master Composter Martin Stott, who has often run free composting workshops at Barracks Lane Community Garden, for whom I freelance. It's also fun to chat to fellow potato fans about your favourite varieties.

Cultivate's Emma carefully checking her potato list

After the serious, but fun activity of choosing potatoes, I took the opportunity to wander about Ryton gardens. As the weather has been so mild, there was lots more to see than usual at this time of year. The small organic garden (4.5m x 6m) was looking inviting, with its lovely rounded 4-bed rotation system edged by bricks. It also has a small pond (for frogs etc), a cold frame, a compost bin and a rainwater collection system; displaying what can be grown in a small but bio-diverse home garden.

The small organic garden 

The 'All-Weather Garden', was a polytunnel full of salads, Chinese cabbages and herbs that can be picked throughout winter. As mentioned recently, my long-term plan is to have a polytunnel on my allotment, and it was good to get a sense of what I'll be able to grow and eat once I do have one.

The All -Weather Garden

The layout of the Elysia Biodynamic Garden is lovely, with a mix of annuals, perennials, fruit and vegetables grown.

Elysia Biodynamic Garden 

There is also a new display garden at Ryton, the Cuban Organoponicos. Based on the types of urban gardens and food systems Cuba created after the fall of the Soviet Union, it displays a mix of fruit and vegetables that can be grown in small spaces using recycled materials.

Cuban Organoponicos garden

Visiting all the different gardens at Ryton made me realise I really must return for a visit in Summer, to see them in full bloom and cultivation.

Returning to potatoes, I attended a really engaging talk '20 challenges and opportunities for potatoes' by Alan Wilson, which I've written about in a separate blog.

As ever, I thoroughly enjoyed myself at Potato Day. Now it's time to get on with chitting the taties and to look forward to getting them into the ground. Will I like the new varieties I'm trying? Will my old favourites be pushed aside for new taties on the block? Stay tuned.