Growing Potatoes

Last year I purchased several new potato varieties from the Main Potato Lady and this winter we enjoyed the unique flavors of each variety.  

Four of the seven varieties I planted this spring.

Potatoes options at most grocery stores are Russetts or Reds and very little in between.  But when you grow your own potatoes you have so many varieties to choose from, different colors including red, yellow, blue and purple, different harvest seasons called Early, Mid-Season and Late Season.  Potatoes that are great for mashing, hold their form for soups, and are wonderful for baking. They have names like Green Mountain, Purple Viking, Nicola, Gold Rush and Sangre. 

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Why spend the time and garden space to grow potatoes when you can purchase them so inexpensively at the grocery store?  In a word - chemicals.

Potatoes are one of the Environmental Working Groups "dirty dozen".  The dirty dozen are the 12 vegetables and fruits with the highest concentration of chemicals from pesticides, herbicides, fungicides and any other chemicals the grower deems necessary for industrial production. 

You would think that root vegetables would be somewhat protected from chemicals but this is not the case with potatoes.  I have read that some commercial potato farmers will not even eat their own product.

Why so many chemicals?  Potatoes are grown with chemical fertilizer, then they are treated with pesticides to ward off potato bugs or other insects.  Right before harvest they are sprayed with a herbicide to kill off the top growth as it interfers with the machines that harvest the potatoes.  Add in "anti-sprouting" agents and you have a rich chemical soup to go with your potatoes.

When deciding how to budget your food dollars experts encourage consumers to spend their organic food dollars on fruits and vegetables on the dirty dozen list to get the most bang for their organic food buck.  Growing potatoes, rather than purchasing organic potatoes, saves money.

Getting Started

The first step is to decide which varieties of potato you would like to grow and get the "seed".  Seed potatoes are sold specifically to be planted.  They look just like the potatoes you would peel and mash for dinner.  

All sprouted and ready to plant.

Some gardeners just plant potatoes that they buy in the grocery store, and that can sometimes work if the potatoes have not been treated with an anti-sprouting agent and are at the right "age" for growing.  

Potatoes stay dormant for a specific period of time.  If you plant a potato while it is in its dormant stage it will not grow.  Seed potatoes are sold when their period of dormancy is over and they are ready to sprout.

Planting

To get a head start, expose your seed potatoes to indirect sunlight (indoors) for several weeks until they begin to form sprouts.  The sprouts can look green, blue, or red depending on the variety. When the potatoes are planted these sprouts will form leaves that will erupt from the ground two to four weeks after planting. 

Potatoes should be planted in the early spring in soil that is loose and well drained. Non-compacted soil will allow the roots to grow without resistance and well drained soil will prevent root rot.

A broad-fork works well to loosen the soil without disturbing the microorganisms in the soil.  

A broad-fork gives the soil a lift.

If you use organic garden methods and don't walk on your garden beds, you seldom need to loosen the soil.  Earthworms will move in and out of the soil doing the tilling for you.  

Newly shoveled soil with lots of worm holes.

Dig shallow holes in your garden bed about 12 inches apart.  Place several seed potatoes in the hole with the sprouts point toward the sky.  

Some gardeners like to cut their seed potatoes in sections to increase the number of plants.  Before cutting make sure that the potato is bigger than the size of an egg and there is at least one "eye" (sprout) on each piece, as the eye will grow into the potato plant.

Cut sections should be spread single layer on a paper towel or cotton sheet and allowed to dry for 24 to 48 hours  prior to planting to "cure" the cut edge and prevent spoilage. Gardeners in wet climates can also coat the pieces with horticultural sulfur powder to prevent rot.  

I save the small potatoes each fall to use as seed potatoes and plant them whole to simply the process. 

Seed potatoes planted with the sprouts pointing up.

Cover the potatoes with an inch or two of soil and and smooth the top with a gentle pat.

One side of a garden bed, planted and ready to cover with soil.

If you want to prevent weed seeds from germinating, you can cover the garden bed with a thin layer of aged leaves or grass clippings.  After the plants emerge, you can add an extra layer of mulch to keep the weeds in check.

Rotted leaves make a good weed block.

Growing

In two to four weeks, depending on weather conditions, you should see small green leaves in a rosette shape emerging from the soil.  Although potato plants are fairly cold tolerant, they will freeze and turn brown if temperatures drop below 32 degrees, so time your planting accordingly.

The potato leaves push up through the thin layer of mulch.

As the plants grow, the leaves will lengthen and will look a bit like a tomato plants as both are members of the nightshade or Solanaceae family.  The nightshade family of plants also includes egg plant, pepper and tomatillo.

Potatoes need moisture to grow, so water your plants if rainfall is not sufficient to keep the soil moist.

Potato plants in bloom.

Blooming flowers on your tomato plants indicate that the plant is forming tubers (potatoes). Different varieties of potatoes have different colored flowers, including white, pink, and lavender. 

The tubers will grow very close to the surface of the soil, and need to be several inches under the soil or mulch to prevent sun damage.  Some people "hill" them by raking soil up against the base of the plant creating a mound.  I have also used straw, leaves and grass clippings to create a protective layer.  

When exposed to the sun, potatoes will become green.  The green skin and flesh contains solanine which, in high concentrations, is considered a poison.  If you harvest a potato with green skin, be sure to cut off all the green areas before eating.  To prevent greening after harvest, always store your potatoes out of sunlight.

Colorado potato beetle larvae.

Pests

The Colorada potato beetle is the most common pest to plague potato gardeners.  This round, hard shelled bug with yellow and black stripes, lays bright yellow clusters of eggs on the under side of potato leaves.  The bugs hatch and the slimy (almost snail like) larvae grow by eating the leaves.  A potato plant can be stripped of all its foliage in a matter of days.

Colorado potato beetle

Potato beetle eggs

Potato beetles working to create the next generation.

There are several ways to combat potato beetles.  If you have just a few plants, you can simply remove the bugs and and squish the egg clusters by hand.  Bugs can be placed in a glass of soapy water to drown or smashed under foot.

Securely covering the plants with a floating row cover can help to keep potato bugs at bay (provided they did not winter over in the soil of your planting bed).

You can also spray the plants with B.t. bacterium when the newly hatched larvae emerge.  The buds will die after eating leaves containing the bacteria.  I only use the spray when I notice a large number of larvae on the plants as healthy plants can withstand some beetle damage.

B.t. bacterium is approved for use on organic farms.  This link explains why this pesticide is safe for both the environment and potato eaters.

This link has more non-toxic treatment methods for potato beetle infestations.

The Harvest

Potatoes can be harvested throughout the gardening season (once the plants and bloomed and tubers have formed) by reaching under the soil and pulling out individual potatoes.  The size of the potatoes will be determined by their stage of development.  If you take just a few from each plant, the plant will survive and continue to form and grow potatoes.

In the fall when the tubers are done growing, the top growth will turn brown and die.  You can harvest the fully grown potatoes at any time after this point, but be sure to dig them before the ground freezes (or the gophers get them).

I like to use a broad-fork to loosen the potatoes from the ground.  It is like a treasure hunt when you reach your hand into the soil and pull up potato after potato.  Use care so you don't puncture the potatoes with your fork or shovel.  

Different varieties of potatoes have different growing patterns, with some varieties forming tubers in a small circle under the plant and others (like fingerlings) forming tubers far and wide, making it easy to slice one while digging.

Winter Storage

Potatoes need to be "cured" prior to storage.  Shake off the excess soil, bring indoors, set single layer on a cotton sheet, then cover with a second sheet  This method prevents greening, while allowing the potatoes to dry and cure.  During the curing process the skin will become thicker helping to preserve them for fall, winter, spring and sometimes even summer use.

After your potatoes have cured, place the potatoes in a burlap bag and store in a dark, cool, and humid spot.  A root cellar is ideal, but a garage that stays around 40 degrees will also work.  If your storage area is not humid, you can place your potatoes in sand in large containers and keep the sand damp (not wet as they will rot).

Seed Saving

After curing select a number of small potatoes and save these for next year's seed.  The smaller potatoes work well for seed as they do not have to be cut prior to planting.

If you have planted several varieties, be sure to label the seed potatoes with the variety's name.  Seed potatoes can be stored in burlap bags following the same methods used to store the potatoes bound for the dinner table.  Write the name of the variety on the bag with a Sharpie marker to identify each variety.

Then enjoy your harvest all winter long.  And if you have a few potatoes left in the spring, you may want to try this Nettle soup recipe.