How to Grow the Best Organic Potatoes this Summer
Welcome to Week 5 of Crop of the Week! Today we’re going to talk about the (not so) humble potato, but if you’d like to see the previous weeks’ crops, here you go: Peas, Beets, Brassicas (cabbage family), and Salad Crops.
You need to forgive me as I’m going to totally geek out on potatoes today, so this post is going to be longer than usual.
If you don’t want to hear all about my potato plant geek-out, just skip down a bit in the post to the growing and care of your potatoes (Pre-planting is the first section). BUT, they’re an amazing plant, the third most important food crop in the world, with a diversity that boggles the mind, so you might like reading about them.
Diversity of Potato Varieties (Solanum tuberosum)
Unless you’re a plant geek (like me!), you’re probably most familiar with Russet potatoes, and maybe those cute, colorful little potatoes you can find in little bags in the grocery store. That’s not the full story, not by far!
There are actually 4000 edible varieties of potatoes in the world, with 180 more wild varieties that can’t be eaten due to their bitter taste. The wild varieties, though, are important for genetic diversity and disease resistance.
If you’d like to see just some of the amazing varieties of potatoes, check out this link. You’ll need to scroll down the page a bit, but there is an amazing picture of some incredibly diverse and colorful potatoes.
As you can see above, potatoes come in the traditional, familiar white, but also blue, red, pink, purple, brown and yellow. Pretty cool, huh? Many of the more brilliantly colored varieties will lose some to all of their color when boiled, so if you want to serve your family purple potatoes, preserve the color by roasting them.
And don’t forget, as an email subscriber, you’ll have INSTANT access to my Subscriber’s Resource Library that includes super handy dandy cheat sheets on the planting, growing and harvesting of not just potatoes, but ALL the Crops of the Week so far. If you’re not a subscriber, you can see what it’s all about here.
History of Potatoes
Potatoes are native to the Andes of South America, but can be grown in altitudes from sea level all the way up to 15,000+ feet! They do grow best in cooler conditions, but even those in warm climates can grow them, with special care (more on that below).
In 2017, according to potatopro.com, 388 million tons of potatoes were grown in the world. China is the #1 worldwide producer of potatoes, with India #2. The US comes in at #5.
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Irish Potato Famine
I imagine that, unless you’ve been living under a rock your whole life, you’ve probably heard of the Irish Potato Famine, but maybe you don’t quite know the whole story.
When Europeans brought potatoes back from Central and South America originally, they only brought back one or two varieties. Now, it’s possible they brought back more than that, but the ones that didn’t keep well didn’t survive the long ocean voyage. Whatever the case, most of Ireland was planted in what was termed the “lumper” variety of potato.
This went well for awhile, as potatoes grow beautifully in Ireland’s climate. They were cheap and easy to grow, and subsistence farmers had abundant harvests and food to feed their families.
That is, until 1845, when Phytophthera infestans (otherwise known as late blight) was inadvertently introduced from North America. Over the next eight years, over one million people in Ireland died of starvation, and another million were forced to leave the country in search of subsistence elsewhere.
Because the entire crop of potatoes in Ireland was of one variety, and potatoes are propagated vegetatively (not from seed), every potato was an exact genetic clone of every other one, meaning they all had the exact same (clearly high) susceptibility to late blight.
Had there been even 3 or 4 varieties of potatoes being grown at the time, it’s possible that one would have been more resistant to the disease and the famine wouldn’t have happened.
This is an obvious, tragic lesson in the dangers of monoculture (growing only one variety of a certain crop). Unfortunately, we’re slow learners.
Modern Monoculture Disasters
In 1970, over a billion (yes, billion, with a B) dollars of corn were lost due to a fungus, and in the 1980’s, CA grape growers lost over 2 million acres of grape vines when a new variety of the bug, grape phylloxera, invaded their crops.
Would these devastating losses have happened if multiple varieties were grown? It’s possible, but the chances that one variety would have had at least some resistance to the bug or disease would certainly have improved with crop diversity.
Crop Diversity to the Rescue
So, what’s the lesson here? Grow more than one variety of a crop, experiment, have fun!
Yes, if you’re saving seeds and your crop could potentially be cross-pollinated, you’ll have to take precautions, but there are so many types of not just potatoes, but cucumbers, tomatoes, and almost every other food crop, why not have some fun?
I, for one, am growing seven varieties of tomatoes this year. Of course, I have a bit of an addiction to trying new and different varieties of just about everything, so don’t go by me.
Caution: Genetically Modified Potatoes are out there
I wasn’t aware until doing research for this post that genetically modified potatoes exist. Certain Russet potatoes are modified to produce an insecticide throughout the tuber.
However, this insecticide has been found damaging to the vital organs of rats. Yikes!
I already buy organic potatoes because conventional potatoes are quite literally doused in insecticides and herbicides, but I now have an even better reason to buy organic.
Don’t worry, McDonald’s fries aren’t GM
I also found out that McDonald’s, which uses a huge amount of the Russet potatoes grown every year in the US, claims not to use GM potatoes in their fries. You’ll still have to worry about high cholesterol and heart disease, but not insecticide damage! LOL
Ok, let’s move on to how to grow your diverse and interesting crop of potatoes.
MOST IMPORTANT: Purchase certified, disease-free seed potatoes
Unfortunately, potatoes are susceptible to many diseases, not just late blight. For this reason, it’s vital to buy seed potatoes that are certified disease-free. Although you can save potatoes from the previous year’s crop (as I did this year), this won’t work for more than a few years. After that, your crop will get smaller or you’ll get some type of disease, and you’ll have to purchase new seed potatoes.
One fun place to check out for potatoes is the Maine Potato Lady. She has lots and lots of varieties (many organic), and even some onions and garlic as well. I purchased from her last year and got 4 different varieties, one of which was bright purple! So much fun to cook and eat!
Chit your Tubers
Sounds like a dirty word, doesn’t it? This just means spreading your seed potatoes out on a tray in a warm, sunny place until they grow small green shoots. It gives them a bit of a head start and is a good idea.
Prepare your Tubers for Planting
If your seed potatoes are small (around golf ball-sized), you may plant them whole. Otherwise, you’ll want to cut them into pieces with 2-3 eyes each. Let them sit for a day in the sun to cure before planting to discourage rot.
Seed potatoes can be planted in rich (add some compost) soil in full sun 2-3 weeks before your last frost, as the young plants can handle a light frost.
If you live in the south, be sure to get your potatoes in very early. If you live where it’s very warm, you may want to try planting in the fall for an early spring crop, as potatoes thrive in cool weather.
Be sure your soil is somewhat acidic, as potatoes grown in alkaline soil are more susceptible to scab (more on that below).
Plant your potatoes in trenches or holes 6 inches apart, then cover them with 4 to 5 inches of soil. I’ve also had success with placing them on the surface of the soil and covering them solely with straw. This has several advantages, including ease of harvest, and is a viable alternative to soil.
My grandmother, who was a gardening genius, believed that planting in straw kept bugs from laying their eggs (because they didn’t want to do it in straw and there was no soil available). I don’t know if it’s the truth, but I’ve been growing potatoes for 4 or 5 years now with minimal to no bug problems.
It’s totally up to you what you prefer to do. Keep in mind that growing only in straw will result in slightly smaller potatoes.
Potato Plant Care
Regardless of the method you use (straw or soil), as your plants grow, they must be covered. You’ll want to let the shoots grow a few inches, then cover them with soil or straw. I always leave just the tip of the shoot sticking out so it can get the sun.
Once you’ve got a mound that’s about molehill size (and we ALL know what they look like, don’t we?), it’s easiest to use grass clippings, leaves or straw instead of continuing to mound with soil.
By the way, just in case you don’t know, there are two reasons you mound the soil up around the plants. One, they will grow potatoes all along the stem if they’re covered in soil or straw. Two, if those potatoes are exposed to the sun, they produce a mildly toxic byproduct called solanine. Although you won’t die from it (no, green potato chips actually WON’T kill you!), solanine does make the potatoes taste bitter.
Keep watch for flowers, as there are two things you should do at that time.
First, this is the time to stop hilling and mulch your potatoes if you haven’t already.
Second, you should water them heavily at this time, as this is when much of the initial tuber production is going on.
TIP~ If you happen to notice any seed heads appear after the flowers are gone, just clip those off. They’re not necessary or helpful for your plants.
An Early Harvest
About 2 to 3 weeks after your plants stop flowering, if you’d like to sneak an early harvest of tender, yummy, new potatoes, that would be the time to do it.
You’d like a recipe for those wonderful new potatoes, you say? Well, I have just the one right here! As a bonus, if you’re growing herbs or garlic, you can use them in this recipe too! YUMMMMMMM!!!!
The Main Potato Harvest
As late summer comes, you’ll notice your potato plants begin to wilt and die off. If you have time to allow the potatoes to sit in your garden for 2-3 weeks after this happens, that’s ideal.
However, if your first frost threatens, you’ll have to dig your potatoes right away. Either way, they’ll be fine, they may just be a little smaller if you’re forced to dig them earlier.
Be sure to always harvest your potatoes in dry conditions (not right after a heavy rain). Dig gently so as not to damage your crop, as fresh new potatoes haven’t yet developed the tougher skin you’re used to in grocery store potatoes.
If you’ve planted in straw, you can dig them completely by hand, which gives you the best chance of not damaging them (although I have occasionally put a scratch or hole in one just with a fingernail!).
Any potatoes that are damaged should be used immediately. You can either cook and eat them, or if you have a lot of them, cook them off, mash them and freeze them. Frozen mashed potatoes thaw beautifully, and they’re so convenient if you want to make a Shepherd’s Pie or just have mashed potatoes one night for dinner.
Storing your Harvest
Leave your undamaged potatoes to dry in the sun for no more than an hour, then allow them to cure in a warm, dry place out of direct sun for a week.
They should be stored in a cool, dry place around 40F, in a paper bag or a container.
If you intend to store your potatoes long-term, try to plant varieties labeled good for storage. For instance, if you check out this Maine Potato Lady link, you’ll see that this variety is considered good for storage. You should be able to find this information on any potatoes you order (and if you can’t, I would order elsewhere as this is important information).
I have found, although I have no scientific evidence to support this (other than my own observation over several years), that larger potatoes (and sweet potatoes actually) store longer than small ones. To that end, I would suggest using your smaller potatoes first and leaving the larger ones for storage.
Potato Pests and Diseases
Unfortunately, I have to talk to you about potato pests and diseases because they can be numerous. However, with good sanitation, crop rotation, planting the proper varieties, and companion planting, you can minimize a whole lot of issues.
For instance, late blight, although a horrendous disease, is, as its name implies, a late in the season disease. If you know you are in an area prone to late blight (or you’ve experienced it before), planting an early potato variety will allow you to harvest before the disease hits.
One of the best ways to prevent late blight is to rotate your crops.
This means that no potato family crop (this includes tomatoes, eggplants and peppers) should be in the same ground more than once every 3 years at minimum. If late blight has struck in the past, that ground shouldn’t have any potato family plants for at least 5 years.
Here’s a good article on late blight in tomatoes, which also applies to potatoes, including a real-time tracker so you can see if it’s in your area, which will give you a good idea of what to look for, and what to do if you should get infected. I’m not convinced I agree with weekly treatments for prevention, but if you live in an area that’s showing heavy infestation, it might be something to consider.
Unfortunately, late blight isn’t a disease that can be taken lightly. It WILL destroy your crop, and then it will spread to your neighbors’ crops as well. If you happen to live close to farms, PLEASE be careful to do everything possible not to pass it along should you get infected.
Early blight can also destroy your crops if they become infected. The late blight link above has a good picture of early blight as well, if you need to know what it looks like. As with most other diseases, proper crop rotation goes a long way towards preventing this disease.
Because both late blight and early blight are fungi, there are other things you can do as well. Making sure to water only from the bottom, never from above, is one way. Soaker hoses are a wonderful option, and you can find a nice selection here.
Soaker hoses are the only way I water my garden. I have a whole system, which I’ll detail in an upcoming post once I have it set for this season.
Blackleg is, unlike the blights, a bacterial disease, but can be equally devastating. Interestingly, it can also infect carrots, parsnips, broccoli, corn and sunflowers, according to this website, so avoid these in your rotations if blackleg is a problem in your garden.
The symptoms of blackleg include yellow foliage that progresses to a black, slimy rot, especially along the stems.
As with so many of the other diseases, good crop rotation practices are essential. It’s also very important that you use only certified disease-free seed potatoes to prevent this disease. Blackleg likes very wet soil, so good drainage is also essential.
Scab is not as devastating as some of the other diseases, although it causes scabby lesions on the potatoes themselves, which can be a problem if you’re trying to sell your crop.
The easiest and best way to minimize scab issues is, again, crop rotation. However, a further step to be taken is to be sure your soil is acidic, as most scab cannot live in soils with a pH below 5.2.
It also tends to occur in dry soils, so consistent watering is helpful.
Verticillium wilt is yet another fungal disease that affects potato family plants. It starts with yellowing leaves, then there’s widespread wilting throughout the plant. If you cut the plant open, you’ll see blackening of its vascular (vein) system.
As with the other diseases, good crop rotation practices and consistent watering will go a long way towards preventing this disease.
There are varieties of potatoes resistant to this disease, so planting one of these will help as well. Russet Burbank is one variety listed as resistant. Unfortunately, it’s also a GM (genetically modified) variety.
Again, if you go to the Maine Potato Lady catalog, each variety includes its resistance to various diseases in the description. I wasn’t able to find an easy-to-read listing of resistant varieties anywhere else. If you find one, I’d love it if you’d put it in the comments!
Although there are again, unfortunately, quite a few pests that can plague your potatoes, they aren’t going to be as devastating as the diseases we just talked about, and unless you’re growing acres and acres of potatoes, you’ll be able to control them fairly easily.
In general, row covers offer your best bet at controlling most any insect pest. There are a bunch of options here. If you need more specific help with what kind of row covers to buy, please feel free to comment and I’ll do my best!
As with plant diseases, healthy, happy plants are much more able to withstand and even fight off pests. Healthy soil, consistent watering and full sun will go a long way towards keeping your plants pest-free.
Now, let’s look at each pest a little more closely.
Colorado Potato Beetles
These guys are pretty common, at least in my garden. The easiest and most effective control for these is just to hand pick them and drown them in a container of soapy water. It also happens to be very satisfying to drown the little buggers, but we won’t talk about that.
I’ve never had aphids on my potatoes (probably because they love my milkweed and honeysuckle so much, **sigh**), but that gives you an idea for a way to control them: Just plant something they like better! Aphids particularly love roses, honeysuckle and milkweed.
You can use a strong jet of water to knock them off your plants or a neem oil or insecticidal soap, if you really have a heavy infestation. Try to use the neem oil later in the evening when pollinators aren’t active so they don’t come in contact with the wet product.
The best control for flea beetles is to plant radishes close to your potatoes as a trap crop. Neem oil will also control these little buggers. Oh, and they look just like fleas, by the way, they’re tiny and black and they jump like crazy.
If you don’t know what these guys look like, there are some pictures here. The best way to control them is handpicking and drowning, but PLEASE wear gloves when handling. They’re called blister beetles because they exude a nasty substance when threatened that can burn your skin.
These guys look like little, bright green grasshoppers, and you’ll also notice that they have a rather distinctive sideways gait. You might notice leaf hopper damage before you notice the bugs. There will be browning and drying of the margins of the leaves on your plants.
The most effective way to deal with leaf hoppers is, again, either insecticidal soap or neem oil spray. However, unless you have a very heavy infestation, leaf hoppers rarely do enough damage to require eradication.
A Note on Neem Oil & Insecticidal Soap Application
Please remember that even though these products are considered organic, they can still kill more than just the pests you intend to kill.
It’s ideal to try other options, like row covers and handpicking, first. Anything that will kill a pest can also kill a beneficial, and this is obviously something you want to minimize. Don’t be lulled into thinking these products are perfectly safe just because they’re organic. Many of them are quite safe when used correctly, but they aren’t without risk.
If you’ve managed to hang in and read this very long post, thank you! I hope you’ve found it interesting and helpful, and that you’ll give growing organic potatoes a shot this summer. The pictures at the end of this post are pinnable and I’d love a pin or two if you have appropriate Pinterest boards. As always, smile and have a crazy organic day!
As with the other Crops of the Week, there’s a printable cheat sheet available in my Resource Library for you. If you’re not already an email subscriber, you can sign up here. You’ll never receive spam (I hate it as much as you do!), but you will receive instant access to my Resource Library and a weekly newsletter with information and happenings around the blog. Please join me, you’ll be glad you did!
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