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The Midwestern Gardener’s Ultimate Guide to Growing Potatoes

The humble potato is a crop of lore and antiquity.  It is an ancient food source originally cultivated in the Peruvian highlands almost 10,000 years ago, where hundreds of varieties of potatoes are still grown in its native range to this day. 

And did you know, this humble potato was the first vegetable grown in space?  Potatoes were grown aboard the Space Shuttle Columbia in 1995, as a joint project between NASA and the University of Wisconsin.  What a history this staple food has led over the millennia!  Potatoes are in the Solanaceae family of plants, it is a close relative of tomatoes, peppers and eggplants.  

Jack’s Hardware and Farm Supply seed potatoes are coming from Mythic Farm (formerly known as Vermont Valley Community Farm) out of Blue Mounds, WI.  They have been growing certified organic seed potatoes for over 20 years.  

But what exactly are “seed” potatoes?  As you may or may not know,  you get more potatoes by planting pieces of potatoes (not from potato seeds).  New plants grow out of the eyes of a potato, feeding off the starches and nutrients in the potato as they start a new life.  Of course this means any potato can be planted, whether from the grocery store or from leftover potatoes from your previous year.  However, doing this leads to the distinct possibility of disease issues, especially if you just plant potatoes from the grocery store, you could be bringing a disease vector into your garden soils, and could create a nightmarish problem for years to come.  Certified seed potatoes are verified to come from disease-free fields.

Potato Varieties

Jack’s carries 5 varieties of certified organic seed potatoes: German Butterball, Goldrush Russet, Red Endeavor, French Fingerling and Austrian Crescent.  (Click the link to see a picture from the Mythic Farm website.)

  • German Butterball:  A lightly russetted potato with yellow skin and flesh These plants produce delectable buttery balls that are hands-down the best-tasting roasting potato in the winter.  With flesh just dry enough for a fry or a hash, the Butterball has high yields, good storage qualities and shows some virus and scab resistance.  Large prostrate vines with few white flowers.  Mid-Late Season Variety, 80-100 days to harvest.
  • Goldrush Russet:  Russeted skin, white flesh, high yields!   The perfect baking potato, and it fries up very well.  Some russets can be fussy in our humid climate, but Gold Rush performs even in wet years or poor soils. Give plants a lot of space to allow tubers to grow to their full potential.  Mid-Late Season Variety, 80-100 days to harvest.  Susceptible to blights and fusarium.
  • Red Endeavor:  A new variety from the Wisconsin breeding program. High yields of uniform dark red-skinned tubers with white flesh are favored by chefs for roasting and steaming. A vigorous plant with some resistance to scab.  A mid season variety, 70-90 days to harvest. 
  • French Fingerling:  Radiant, dark rose-red skin, yellow flesh with pink lines.  French Fingerlings are sweet little potatoes that you want to pick on the early side to enjoy their tenderness. Creamy, smooth texture with exceptional flavor lends itself well to salad.  Plant at 12 inch spacing and get high yields of good sized fingerlings. They have very aggressive plant growth and we have found them to be resistant to leaf hopper feeding.  Mid-season variety, 70-90 days harvest.
  • Austrian Crescent: A high-yielding, large fingerling potato with a golden-yellow flesh that’s buttery and delicious. They are an elongated potato that may reach up to 10″ in length at full maturity.  Widely sought after by chefs and food connoisseurs.  Moderate scab resistance. Mid to late season, 90 days, stores well.

A Basic How-to on Growing Potatoes

When to plant

Ideally wait for the soil to warm up sufficiently.  Cold, wet soil will delay potato emergence, and possibly lead the seed potato to rot.  If you are planting in a raised bed you will be able to plant earlier, as raised beds warm up earlier in the Spring weather.  Each Spring is a bit different, so keep an eye on weather forecasts, and once the weather turns toward warmer Spring temps (daytime highs consistently in the 60’s), it;s time to prep for planting.

Pre-Planting Prep

When you are ready to plant potatoes, there are a couple simple steps to follow before planting.  If your potatoes have started to sprout and have sizable stems already growing out of them, don’t worry, just break them off, and this will not harm the potatoes in any way.  

Secondly, to help get the most out of your potatoes, any that are of larger size, and have multiple eyes, can be cut in half, or even quartered.  Ideally any potato piece you are going to plant, should have a minimum of two eyes on it.  You want to do this at least a couple days before planting.   Leave the potato pieces left out exposed to air, so that the freshly cut sections dry out and scab over.    

Preferred soil (or soil-less growing styles)

Potatoes prefer a sandy, well-drained soil, well-drained being the key component, as a heavy clay soil that holds onto water can lead to the potatoes rotting or having disease issues.  If you have raised beds in your garden, this is a great option for growing potatoes.  Other options are growing potatoes in a bag or a straw bale if you don’t have ideal soils for potatoes.  I won’t dive into it here, but there are a plethora of videos and blogs out there.

Plant Spacing

Plant spacing will depend in part on the variety and what you want results you seek to achieve.  Plant a potato seed every 12” as a general rule.  However, if you want more, smaller potatoes, then you can plant every 6”, or if you want fewer, larger potatoes push beyond 12”.  Not all potatoes respond the same way, but that is a general rule to follow.  Of our varieties, German Butterball and Goldrush Russett will benefit from extra spacing, as they are larger plants and tend to grow large potatoes if given the room.

Hilling / Mounding

Many of you may be familiar with the idea of mounding or hilling potatoes.  While not absolutely necessary, it is a recommended practice, and can indirectly increase your yield.  This is in part because potatoes form better tubers and more numerously with soil temps in the 60’s.  The deeper in the soil profile the potatoes are growing, the cooler the soil temps.  

Also, keeping the potatoes well-buried will avoid having potatoes peaking above the soil line and getting green shoulders (which should not be eaten).  As well, the process of hilling/mounding helps to keep weeds away from your potato plants, as they do not compete with weeds effectively, and can lead to a reduced yield. 

There are many ways to hill/mound potatoes, but my favorite method is the trench and fill method.  I dig a trench about 8” deep, piling the soil up along the sides as I go.  Then I plant the potato pieces about 3” under the soil at the bottom of the trench.  Once the plants grow to about 10” tall, I move along and back-fill the trench, effectively leaving about 2-3”of the plant sticking above the soil line.  This is a good time apply a nice layer of compost/composted manure alongside the plants to help with fertility over the growing season. 

Fertility & Watering

Potatoes will produce best if they are grown in fertile soil and kept well-watered through the season.  I have certainly ruined a potato crop by ignoring its watering needs at critical junctures of its growth process.  As to fertility, I personally find that potatoes don’t require as much fertility as some of the other vegetables in the garden, but they definitely benefit from a nitrogen-rich amendment mid-way through their growth cycle.  This could be in the form of an all-purpose fertilizer (Jack’s carries Sustane, a composted and pelletized turkey manure fertilizer) or a composted manure top-dressing.

Pests & Diseases

My personal arch-nemesis when growing potatoes are voles!  They love chewing on exposed potato tubers!  Yet another reason to mound/hill your potatoes as they grow, as this will help keep the new potatoes deeper in the soil and out of reach of a voracious vole.  

As to insect pests, the two main culprits of insect damage to potatoes in Minnesota are Colorado Potato Beetles and Cut Worms.  I won’t go into length about them here, but clicking on the links will take you to the data sheets put out by the University of Minnesota Extension Service where they talk more about identification and solutions to dealing with them.  

There are also certainly diseases to keep an eye out for, specifically Late Blight.  Again, the U of M Extension Service has great information on Late Blight and a variety of plant diseases here.  They are an amazing resource every gardener should have at their fingertips!

What kind of yield can you expect?

There is certainly a wide variation in potato yields, partially depending upon the variety, partially on best growing practices (ie, well-drained, fertile soil, adequate irrigation throughout the growing season).  On average, 5-10 lbs of harvested potatoes per pound of seed potatoes planted is a good rough estimation (though much higher can certainly be achieved).

When to harvest:  Baby vs Mature Plants

Knowing when and how to harvest is important depending upon how you like to use your potatoes.  If you are wanting to store the potatoes well into the Winter, then it is of paramount importance to let the plants die back completely, and even then give them more time to let “skin setting” occur.  This is when the potato will develop a thicker skin as a defensive and preservation method to retain moisture.  If you’re potatoes are running late into the season and are still green when a hard frost is in the forecast, then just cut the plants off (leaving a bit above ground so you know where they are) and let skin setting occur over the next couple weeks.

Now, if you are like me, and loooooove roasted baby potatoes in the middle of the Summer, there is another mid-Summer harvest window.  Once potatoes have begun flowering in earnest, they have usually set a good supply of potatoes, but they are generally small (and oh so tender). I’d suggest waiting (if you can) until the plant has quit flowering.  I will usually dedicate a certain number of plants to Summer harvested baby potatoes.  These need to be harvested carefully, as the skin setting has not occurred, and the skin is very delicate (scrapes and bruises easily and the potatoes do not store well at all).  Once harvested, plan to cook these up within a few days (but seriously, who can even wait a couple days?!).

Always be careful while harvesting not to cut the potatoes or bruise the skin, as these potatoes won’t store for long.  While I try to be as careful as possible, my rule of thumb is to just eat any of the damaged potatoes shortly after harvest, and only the perfect potatoes go into long-term Winter storage.  Once dug, allow them to sit and dry (don’t wash off the soil!  Knock it off, then let the remaining soil dry out, which you gently rub off once it is dry).

Storing Your Potatoes

Potatoes tend to store best at temperatures around 40-45 deg, and 90% humidity.  If you happen to have a root cellar, or a cool moist basement, this would be perfect.  But I have stored potatoes for long periods of time in less than ideal locations.  Just keep them as cool as possible, as humid as possible, as dark as possible.  As with any stored crops, it is a good idea to periodically go through them, and take out any that show signs of rot, As rot begets rot!  

Photo credit: Lukasz Rawa

In Conclusion

By growing potatoes, you are engaging with an ancient lineage of food production.  It is a simple, humble crop that feeds us through the bitter Winters of the North.  Nutritious, storable, easy to grow beautiful plants.  What’s not to love about the humble potato? Let us know your favorite varieties or recipes in the comments!

Stefan Meyer

Stefan Meyer

From the Family Farm to the Urban Farm, to an Agroforestry Center in the Minnesota North Shore, Stefan has explored many facets of farming over the course of his life. A strong love of working with soils, plants and animals, mixed with an ethos of ecological balance and regenerative farming practices, continue to guide him on this journey.

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