Your Comprehensive Guide to Growing Potatoes with Ease

 
Oh how I love thee… let me count the ways.
Comprehensive guide to growing potatoes with ease
   Potatoes have a lot going for them.  They are easy to grow, they are nutritious, there are many varieties with differing harvesting lengths, colors and sizes,  and they can be eaten in many different ways making them a versatile food. Whats not to love?
   Well, one thing not to love is the variety of opinions on how to grow potatoes… and the lack of success people have with
growing them in containers.  You see all sorts of stories on Pinterest and websites about how easy it is to grow them in pots… but often they don’t tell you what little is really produced when harvested.  It doesn’t have to be that way and its very sad to see YouTube videos where people are excited to harvest their container potatoes but end up with a disappointing crop.  That shouldn’t happen to you if you follow the recommendations in this comprehensive guide to growing potato with ease.
   Don’t let that happen to you!

 General Potato information  

Jennifer Debnam

   The potato we typically eat in the United States is a tuber which is a below ground storage place in the stem of the potato plant.  What we call “eyes” are buds that can grow into stems creating new plants. Potatoes do reproduce from berries if allowed to flower.  In the US we eat an average of 126 pounds of potatoes per person a year.  In Canada in 2013 the consumption of fresh potatoes has been on a slow decline over the past decade, but seems to have stabilized in the last few years around 23-25 kg per person per year (50 to 55 lbs).
   Potatoes belong to the Nightshade family (Solanaceae), and are closely related to tomato, pepper, eggplant, tobacco, and petunia.  Potatoes, sweet potatoes and yams are all tuberous roots with above ground flowering plants, but they are unrelated to one another.
   Many people in the tropics and subtropics rely on root and tuber crops to provide their main source of carbohydrate. According to IFPRI’s projections for 2020, demand for root and tuber crops will increase by 55 percent in the developing world, with greatest increases in sub-Saharan Africa and Asia.
 

Modern History of the Potato

   The potato originated in South America and had been grown the for more than 8000 years.  Spanish in search of gold first came in contact with the potato in Peru in the mid 1500’s and was introduced into Europe in the late 16th century and was a major contributor to the population growth of Europe in the 1700’s and 1800’s.  Dependence on potato became a problem when a pathogen went through Europe and resulted in about a million Irish peasants dying of starvation when the potato crops failed.    Potatoes were first grown in North America in the 1700’s on a large scale and today the potato in the most popular vegetable in the United States.
Are potatoes healthy or not?
potato mineral vitamin nutrition   Potatoes are technically vegetables but they are high on the glycemic index meaning they rapidly convert to sugar causing blood sugars to spike and then drop rapidly.  This is one reason potatoes are seen as a cause of weight gain and promote diabetes.
   A new study showed that potatoes (at least the purple kind) reduce blood pressure.  They provide fiber which helps you feel full when eating.  Potatoes also are high in potassium, Vitamins A, C, B6 and once cooked they have resistant starch which revs up the body helping to burn fat.  Other studies though link potatoes to weight gain at least when eaten in some form every day (chips, fries, baked etc).
   Likely, the best advice is moderation and limiting added fats and sodium to your potato preparations.  Eat potatoes with a low glycemic index food (like fish or healthy fats) which is slowly absorbed and will also slow down the potatoes absorption into the body.  Avoid sweet potatoes and healthy alternatives are whole grains like brown rice and quinoa, or beans which are high in fiber and protein but don’t cause the blood sugar spikes.

Growing Potatoesmulticolored potatoes

   The general concept of growing potatoes is that the edible tubers grow above your seed potatoes 4-6 inches below the soil surface along the stem.  When the stem reaches about 4 inches you cover most of the stem with about 4 inches of additional soil to form another layer of potential tuber growth.  You cover the stem like this at least 3-4 times during the growing season to allow potatoes to form in the soil all the way up the soil covered stems.
When should I start growing potatoes?  Potatoes are cool season crops and so they should be started in spring as soon as the soil can be worked.  This can be as early as 4-6 weeks before the last frost as potatoes can withstand some light frosts.  Optimal soil temperature for tubers to grow is around 60-70 degrees.  As potatoes are cool season crops they don’t like temperatures too high… Over 80 degrees is not helpful.
Where do I start growing potatoes? They must have at least 6 hours of sun a day and more is preferable.  See below for planting locations like containers vs ground.
What should my soil be like to grow potatoes?  Potatoes like light fluffy soils but can be grown in average non-rocky soils if its well-drained.  Working in organic materials will help with nutrients and water retention.  I tend to include a bag of chicken manure when starting my potatoes.  Potatoes prefer slightly acidic soils with a pH range of 5.8 to 6.5.  Typical soils in the Pacific Northwest with our rainfall tend to be slightly acidic normally.
What are the watering needs for potatoes? Potatoes need consistently moist soil but not soggy soil.  Inconsistent moisture is one of the big problems with growing potatoes and can result in mis-shapen  and poor quality potatoes.  Use drip irrigation if possible especially during hot or dry seasons.
What kind of seed do I use?  seed potato and leaves
Use certified disease and pest free seed potatoes.  These are not treated with retardants to stop eye growth.  Even though eyes still form on store bought potatoes its not a vigorous as non-store bought.  And store bought may harbor disease or insects that are not threatening to humans but could affect a crops growth.
How do I choose a potato type to grow?
   Potatoes are loosely classified as early, middle and late season.  All can be planted as early as March or April but mid-season potatoes can be planted as late as July 1.  Late season potatoes tend to be good for winter storage.
Early – reach maturity in 75-90 days (some saw as early as 60 days).  Examples: yukon gold, Red Norland, Irish Cobbler, King Henry
Mid-season/Main potatoes – reach maturity in 95-110 days.  Examples: French fingerling, Kennebec, Red Pontiac, Yellow Finn
Late season/Storage potatoes – reach maturity in 120-135 days.  Examples: German Butterball, Butte, Cal White, Russet Norkotah, Katahdin, and most fingerlings.
   ** I am growing German Butterball again this year and now trying California White.  I grew Yukon Golds last year and they did great… but I can get those in the store so I wanted to try something different.
 
Do I plant the whole potato or do I cut potatoes for seed potato eyes
Small seed potatoes (smaller than an egg) can be planted whole, but larger potatoes can (and should) be cut down into smaller pieces of about 1 inch thickness.  Each piece should have about 2 eyes on it.  If you are cutting into smaller pieces let the cut edges dry for about 24 hours to form a dry crusty barrier to prevent disease
What is Chitting and why should I do I it?  It’s helpful to chit the seed potatoes first before planting.  This means you allowing them to start sprouting shoots see picture of blue bag with shoots started). Place them in a well lit area but out of direct hot sunlight until the eyes form and grow to about 3 inches in length.  Be careful not to break these eye growths when planting (it will stil grow but your work in chitting is lost if they break).  When you plant try and have as many of the growths on the potato facing up.

Planting techniques:

Harvesting potatoes
What is Traditional hilling? 
This traditional way is to dig a narrow trench about 6-8 inches deep.  At the bottom of the trench add a layer of compost so when you plant the seed potato is about 4 inches below the surface. Then place the seed potatoes about 10-12 inches apart within the row with rows about 24-26 inches apart from another row.  When the stem reaches about 8 inches you cover the stem with about 4 inches of additional soil to form another layer of potential tuber growth.  You do this about three times during the growing season.
 
Will potatoes grow in containers?
   Small crops of potatoes can also be grown in large, deep containers, and this is a good way of getting an early crop of new potatoes (new potatoes are just small potatoes that are young and usually pretty tender).
   I recommend containers with good drainage that hold at least 15 gallons and are 24 inches tall.  In the container bottom put about 5 inches of soil (I like to use a mix of potting soil and well composted chicken manure).   As the stems starts to grow add more compost when the stem is about 8 inches.  Cover the stem leaving about 4 inches of green growth. Do this as many times as your container wil allow.  Try and do this in a container that allows you to do this 3 times at minimum.  Keep covering with compost or other material (soil, straw, wood chips) until the container is full.
Potatoes in containers
How many seed potatoes can be put in a container?  If using a 12 in wide container use no more than 3 seed potatoes.  Adjust accordingly… Add another potato for every 2-3 inches wide.
Do Potato bags work?  They can… Although I haven’t had the best results.  I think my error has been not keeping them moist enough as bags dry out very fast.  Often they are not very big so you can only put one or two seed potatoes in.  If you use bags it’s best to fold the bag down to just above the soil you put in them to a low light to hit the new growth, then roll them up as you add more soil.

Care and growing potatoes

Should I fertilize and what kind of fertilizer do I use?  The roots of potatoes are almost in the top portion of the soil. So adding too much fertilizer is not going to help the potato plant as it wil just be washed away and wasted.
   Feed with a liquid organic fertilizer every two to four weeks.  Tomato fertilizer works well also. They like fertilizers with lots of nitrogen and potassium (the N and K in the NPK formula on the bag).   But too much nitrogen can reduce yields and delay maturity.  The nitrogen is mainly to promoted leaf growth so once you have stopped hilling/adding soil and the leaves are fully growing slow down on any kind of high nitrogen fertilizer (some is ok).
Harvest potatoes

Harvesting

 
When can I harvest?  It depends on the type of potato you planted.  Early is 75-90 days (some as early as 60), Mid is 95-110 and late is 120-135
What are the signs the plants are ready for harvest?  The potatoes will be ready for harvesting when the plants start to turn yellow, but they will start providing an edible a crop before then.  If you cant wait gently put your hands in the soil and feel around for new potatoes which are smaller younger ones.  Pull them and let the plant keep growing the others.  Then once the leaves turn yellow and begin to die back, cut down the stem/leaves and stop irrigating.  You can harvest then but waiting about 2 weeks helps promote thinker skins (good for preserving long periods), maturation and healing.
How do I store potatoes?  Potatoes like dark storage around 40 degrees and can last months if held in this low temperature.

POTENTIAL PROBLEMS and TROUBLESHOOTING

What’s wrong… my potatoes are green!  When potatoes are hit by light they can become “green”.  Quite literally they look greenish on the outside and you can sometimes see a thin green layer under the skins.  This green is just chloryhll but it indicates the presence of solanine which can be toxic.  This can be caused during growing if you don’t cover the growing potatoes with soil or mulch well enough.  It can be caused by leaving harvested potatoes on the counter in the sun.
   The presence of solanine causes the skins to become bitter and consuming them can cause illness.  You can minimize the bitterness and potential toxicity by removing the skins and any greenish tinted parts of the potato.
Why are my potatoes oddly shaped? this is caused by uneven moisture during growing… obviously try to keep moisture even

Animal predators  potato animal pests

Slugs & snails: These slimy little guys will eat seedlings and stop them from growing into adulthood.  This is a problem as you are hilling with soil and if slugs are eating all your new growth you won’t have anything to hill.  I use a slug bait that is safer for pets (dog that might eat it) but other DIY deterrents that have some evidence of working include beer traps, and I believe copper strips have been shown to be a slight deterrent.  I have thought about putting strips of copper on the top of my raised beds… It looks cool and it may slightly deter slug).
Colorado Potato beetle: Easy to identify (ywllow and block beetle or reddish orange humpback larva) so just pick these guys and their larva off.
Aphids and leaf hoppers:  Both of these can be sprayed off your leaves with a strong spray of water (hold the leaves so they don’t break).
Flea beetle: use row cover for the first few weeks of growth if you have had this problem in the past.

Diseases common on potato

Potato blight: There is both early and late blight and looks like rot of the stems and leaves and possibly the tuber also.
Once you have the blight its hard to get rid of so avoiding it in the first place is the best advice.  Use certified disease free seed potatoes.  Don’t over crowd you plants, water early in the day and try to avoid watering overhead leaving leaves wet and rotate crops
   Unfortunately once blight starts, it is very difficult to stop. You can remove blight-affected leaves, but removing too many leaves will damage the plant’s ability to grow. Earthing up potatoes provides some protection to tubers. There is no chemical control to stop blight, but you can spray with a protectant spray in June if it looks like it will be a wet one.
Potato scab: This disease looks like it’s name – its scabs on your potatoes… appetizing right?  Actually it doesn’t affect the taste and can be removed.  You usually don’t even know you have it until you harvest so don’t worry too much.
   Ways to avoid potato scab are to practice crop rotation if you have scab last year, used certified seed, lower pH to 5.2 with sulfur, find resistant varieties and don’t use fresh manure.
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I hope you liked this guide to Potatoes… but even more I hope I’ve inspired you to get out in the garden and plant a vegetable.  I read this week that a study recently confirmed what we gardeners know already… that gardening helps your avoid depression and makes you happier.  I know it helps me but let me know if you agree in the comments below!

Other resources:
Check out our other resource guides for Onions, Carrots, Garlic, and seed starting.
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Seed starting workbook.  A short 22-pages filled with techniques to grow organic vegetables in your area this spring or fall.
Single cover sheet page

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