How to Grow Potatoes Organically

Whether you enjoy them baked, fried or roasted, potatoes are a versatile, nutrient-rich staple that can be grown in almost any climate. The beauty of having a garden is that you can grow chemical-free potatoes in wonderful shapes and colors and delicious flavors that you just can’t find at the grocery store!

Here’s how to grow potatoes organically…

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History of Growing Potatoes

The Incas of Peru were the first to cultivate potatoes (Solanum tuberosum) around 10,000 years ago. They experimented and carefully bred thousands of potato varieties, each uniquely adapted to its microclimate in the steep Andes mountains. Peru today remains the world leader in potato breeding, research and development.

In 1536, Spanish conquerers learned just how delicious potatoes were and brought them back to Europe, whereafter Shakespeare dubbed them “love apples.” In 1589, Sir Walter Raleigh introduced potatoes to Ireland. Irish farmers quickly discovered that potatoes could provide enough food for ten people off of just one acre of land—much better than wheat or oats.

The Irish Potato Famine occurred in the 1840s, caused by late blight oomycete, Phytophthora infestans, meaning “plant destroyer.” Before the disease, Irish families ate nearly ten pounds of potato a day! Almost one million people died from starvation or disease during that time period. The Irish Potato Famine gave rise to the field of Plant Pathology.

Potatoes came to the U.S. colonies in 1621 when the Governor of Bermuda sent two large cedar chests containing potatoes to Jamestown, Virginia. Potatoes migrated west with the settlers who moved west, providing reliable food in tough climates. During the Gold Rush, potatoes were highly valued because they were miners’ only source of vitamin C (up to 35% from just one medium-sized spud)!

Potato is the 4th most important crop in the world today. Interestingly, it was the first crop ever grown in space in 1995. Yearly, 35% of the U.S. potato crop is turned into french fries, 28% is used for fresh, and 13% goes to potato chips.

Potato Varieties

Unlike the three or four types of potato at the grocery store, seed catalogs offer hundreds of varieties of potato to choose from, each with its own flavor, texture, culinary uses, and growing requirements. Potatoes come in red, orange, yellow, white, purple, and blue, and in every shape from fingerlings to big, heavy baking spuds. Here is how potato varieties break down:

• Early Season Varieties: These mature quickly (70-90 days) and are great for short growing seasons. Examples include ‘Yukon Gold’ and ‘Red Norland.’ Early season potatoes tend to be thinner skinned, waxy, and more delicate.
• Mid-Season Varieties: These take 90-110 days to mature. Examples include ‘Kennebec’, ‘Red Pontiac‘, and ‘Purple Majesty.’
• Late Season or “Main Crop” Varieties: These require 110-135 days to mature, which is great for longer growing seasons or early plantings. Late season potatoes tend to be thicker skinned, drier, and starchier, which is ideal for storage. Examples include ‘Russet Burbank’ and ‘German Butterball.’

Choose potatoes that suit your climate, the length of your growing season, and your culinary preferences.

How to Grow Potatoes

Potatoes are easy to grow as long as they have lots of sun and well-drained, fertile soils. At the earliest, potatoes can be planted two to three weeks before the last frost date for your region. Seed potatoes can rot if planted too early in cold, wet soil.

It is best to wait for the soil to warm up a little before planting potatoes, so they can emerge quickly and grow without the stress of late frosts. Late March to early May is a good window to plant potatoes in colder climates. In the warmer areas of the world, potatoes can be planted in late fall or early winter.

To find the optimal time to plant your potatoes in your town, ask your garden center or a farmer at the market for the local milestone that signals when it’s time to plant for your area. For example, some people plant potatoes “when the dandelions start blooming.” Others know it’s time to plant the potatoes “once the snow is off the local peak.” Local wisdom on planting times (as well as local pests and diseases) can make a big difference to the success of your crop.

To grow enough potatoes for a whole year, you will need to plant roughly 15 to 20 potato plants per person. Plant early-, mid- and late-season varieties of potato in different areas of the garden, so you can harvest a nice mix of storage, roasting and salad potatoes all season long!

With healthy soil, you can expect about 6 to 10 potatoes per plant, or approximately 50 pounds of potatoes from 2 pounds of seed potatoes.

Soil Preparation for Potatoes

Potatoes thrive in loose, well-draining soil with a slightly acidic pH (5.0-6.0). If possible, test your soil and adjust it’s pH and nutrient levels four to six months before you plant potatoes. This gives the soil time to balance and utilize the added nutrients, and reduces likelihood of pests and disease caused by over-fertilizing or “hot” manure.

In the fall, use a garden fork, broadfork, or tiller to loosen the soil to a depth of 12 inches, and mix in plenty of compost or well-rotted manure to improve yields. Add any pH adjusting nutrients at this time as well. Mulch the bed heavily with straw and leave for winter.

In the early spring, remove mulch to deter slugs, and loosen the soil for planting.

Planting Potatoes

Potatoes are grown from seed potatoes, which are small potatoes (or pieces of larger potatoes) with at least one or two sprouted “eyes” (buds). You can use grocery store potatoes as seed potatoes if they have sprouted. However, grocery store potatoes aren’t certified disease free, so it’s much safer to buy seed potatoes that certified. (Plus the seed catalogs have exciting potato varieties not available at the grocery store!)

Conventionally grown seed potatoes have been treated with fungicides and insecticides, and given synthetic fertilizer. In contrast, an organic seed potato hasn’t been treated with chemicals, which makes them more resilient, with greater vigor and better disease resistance.

In good soil, organic seed potatoes will grow into healthy plants that don’t need chemical pesticides and fertilizers, and the tubers will be more nutrient dense.

To plant seed potatoes, you need to follow a few steps:

• “Chit” Your Potatoes: Place your seed potatoes in a cool, bright spot for 2-4 weeks to encourage sprouting.
• Cut Large Seed Potatoes: If your seed potatoes are larger than an egg, you can cut them into smaller pieces (each with 1-2 eyes). Dip the cut ends of your seed potatoes into agricultural lime and let the pieces dry for 3 or 4 days in a cool, humid place to form a callous that prevents rotting.
• Plant in Rows, Hills or (Deep Containers): Dig trenches or holes 6-8 inches deep. Place seed potatoes 10-12 inches apart in the trenches, with the sprouted eye (bud) facing up to the sky. Fingerling and other small potatoes can be planted with 8 inches between plants. Planting too close can encourage disease, so if in doubt, err on the side of more space. If you are planting in rows, space your rows 3 feet apart.
• Cover the Plants: Cover seed potatoes with only about 3-4 inches of soil, leaving the trench or hole just partially filled. You will backfill and hill up the trench as the plants grow.
• Water lightly after planting. Drip irrigation is recommended to ensure potatoes don’t get too dry during hot weather, and to reduce blight and fungal disease.

Special Tips for Growing Potatoes

Hill Your Potatoes for Greater Yields

As the plants grow, you will need to gently hoe or mound soil up around the stems to cover the lower leaves in a process called “hilling.” Hilling piles loose soil around the vines so the potatoes can form along them, and it also deepens the roots into cooler soil.

When your potato plants first reach 4-6 inches high, bring soil up around the vines from both sides, burying all but the topmost leaves. This can be done with a rake in loose soils or a hoe in harder soils.

Two or three weeks later (or after another 4-6 inches of growth), do a second hilling with an additional 2-4 inches of soil brought up around the vines. Apply a loose mulch that allows the soil to breath after your second hilling. Straw is commonly used because it breathes well, but shredded leaves or grass clippings can be used as long as they are not applied too thickly.

Repeat hilling and mulching every few weeks (or every 4-6 inches of growth) until the plants flower.

Plant Potatoes in Containers

Potatoes do very well in containers, though their yields are not quite as high as when grown in the ground. To plant potatoes in containers, choose a pot that is at least 12 inches deep and wide, with lots of drainage holes. Fabric grow bags and even small trash cans with lots of holes drilled in them are also good options.

Fill your container halfway full with a nutrient-rich potting mix, then add high-potassium and phosphorus organic fertilizer to the soil according to directions (See fertilization, below.), and mix well. Place “seed” potatoes into the pot about 8 inches apart with their eyes facing upwards, then cover with 2-3 inches of soil. Water lightly.

As the plants grow, gradually add more soil to the container (“hilling”) to allow the tubers to develop. Be sure your container is in a sunny location and that you water consistently throughout the growing season.

Water Consistently

Keep the soil consistently moist but not waterlogged. Water deeply once a week, or more often during dry spells. Drip irrigation is highly recommended because overhead watering can spread the fungal diseases that affect potatoes the most.

After your second hilling, apply a layer of straw, shredded leaves, or grass clippings to conserve moisture, suppress weeds, and keep the soil cool.

Companion Plants for Potatoes

Good companion plants for potatoes include marigolds, alyssum, cabbage-family crops, and herbs like cilantro, basil and thyme. Marigolds deter potato beetles. Alyssum and other herbs attract beneficial insects like hoverflies and ladybugs that help control pests. Cabbage, kale, mustard or broccoli planted around your potatoes have a strong smell that helps repel potato pests.

Fertilizing Potatoes

A regular fertilizing routine is important if you want to harvest a large yield of potatoes. As such, the ideal time to begin fertilizing is actually four to six months before you plant your potatoes. Traditionally, farmers and gardeners apply manure to the planting site in the fall before the potatoes are planted in the spring. This provides time for the organic matter and nutrition to break down in the soil so it is available to the plants. Manuring the soil in the fall also prevents the potato disease called “Potato scab” that can occur when fresh manure comes in contact with your seed potatoes.

In the fall, use a garden fork, broadfork, or tiller to loosen your potato patch soil to a depth of 12 inches, and mix in plenty of compost or manure. Add any pH adjusting nutrients like agricultural lime or wood ash at this time as well. Mulch the bed heavily with straw and leave it for winter.

During the growing season, potatoes require plenty of calcium, potassium and phosphorus, but not too much nitrogen. This means that any fertilizer you use should have an “N-P-K” ratio where the N (nitrogen) value is about half of the P (Phosphorus) and K (Potassium) values, such as 2-4-4 or 1-4-3 or 5-10-10.

In the spring, on the same day you begin chitting your seed potatoes (about two weeks before planting), you should remove your winter mulch, loosen your soil and apply a slow-release, granulated organic fertilizer, according to package directions. Dr Earth Tomato and Vegetable Fertilizer is excellent for potatoes, but really, any of the organic tomato fertilizers out there are ideal for the job, because they are low in nitrogen and high in potassium and phosphorus, which help your ‘maters (and your ‘taters) to grow.

Once your plants are 4-6 inches high and you have done your first hilling, it’s a good idea to begin fertilizing your potatoes with an organic, high-potassium, high-phosphorus liquid fertilizer every two weeks until harvest. Fish or kelp meal is a good choice for this. If you do not have access to liquid fertilizer, you can also side dress your hills with more granulated fertilizer, according to package directions.

Potato Pests and Diseases

Good organic pest and disease management in the garden usually involves:

• Crop Rotation: Avoiding planting crops in the same spot more than once every 3-4 years.
• Companion Planting: Growing crops around other plants that help deter pests or draw beneficial, predatory insects to your garden.
• Handpicking Pests: e.g. Removing insect pests and their eggs and larvae by hand.
• Organic Sprays: e.g. Neem oil, insecticidal soap and other organic formulas to help control pests.

Potatoes can be highly susceptible to pests like Colorado potato beetles and diseases like late blight. Here’s how to manage them organically:

Colorado potato beetle – Handpicking beetles (and crushing their eggs) at least twice a week is effective and helps ensure that the pest population will never develop pesticide resistance. For large-scale pest infestations, you can use an organic insecticide containing spinosad, but the beetle population will become resistant over time.

Potato leafhopper – Potato leafhoppers are fast, tiny, hard-to-see bugs that show up in warm weather. If control is necessary, you can use an organic, broad-spectrum insecticide made from pyrethrin flowers.

Potato late blight – This is the dreaded disease that caused the Irish Potato Famine. Late blight occurs in moist weather when fungal spores are present, so cultural practices like proper plant spacing and drip irrigation can help keep foliage dry and air circulating around your crops. Make sure to limit nitrogen on potatoes, as too much in the soil encourages infection.

Organic farmers and gardeners can use a copper-based fungicide for late blight, though it must be sprayed on foliage before you see signs of infection and reapplied regularly throughout the season. If you see signs of blight, remove affected plants immediately, and do not compost the diseased plants.

Potato scab – Scab is a bacterial disease typically introduced to garden soil from seed potatoes. Minimize scab by buying certified disease-free seed potatoes, and making sure your soil has plenty of phosphorus and good compost. Scab prefers alternating wet and dry conditions and raw manure, so apply manure to the soil four to six months before planting, or let it rot into compost before using it as a fertilizer. Scabby potatoes are ugly, but still edible.

Wireworms – Wireworms are best controlled with cultural practices like rotating crops with non-host plants like onions, lettuce, sunflowers, or buckwheat; saturating your soil with water for a couple of weeks before planting to drown them all, and encouraging chickens and other birds to feed on the larvae. If you know you have problems with wireworms, don’t cut your seed potatoes because they are highly attracted to the flesh of a cut potato. Alternatively, use cut potato pieces around the garden as trap bait before planting to help reduce their numbers.

Aphids, whiteflies, and spider mites – Spray insecticidal soap in the early morning or evening when pest populations are the least mobile. You will need to reapply the product after rain or overhead watering to keep the pest control working. Encouraging ladybugs, lacewings, and predatory mites by planting herbs and flowers around the garden will help control pests as well.

How to Harvest Potatoes

New Potatoes: For tender, young potatoes about the size of a ping pong ball, harvest 2-3 weeks after the plants flower. Gently dig around the plants with a garden fork to find the tubers. If your soil is soft enough, you can simply reach into your hill and select a few new potatoes for dinner by hand.

Mature Potatoes: Mature potatoes are ready to harvest when their vines die back and they lose most of their color. This can occur with a frost, or simply when they have reached full maturity. For best storage, hold off on harvesting until four to six weeks after the foliage has died, so the tubers have enough time to toughen up.

Potatoes can be left in the ground for several light frosts, but should be harvested before a heavy frost or snow that could damage the potatoes. Use a garden fork to carefully dig up the tubers, being careful not to damage them.

If you used a grow bag, carefully dump it out or open the lower flap (if it has one) and pull your potatoes out!

Curing and Storing Potatoes

After harvest, remove any stems and leaves and gently brush the soil off them, but DO NOT WASH YOUR POTATOES. Washing them before storage can lead to excess moisture which promotes rotting and shortens their shelf life. Always wash potatoes just before you are ready to cook them.

Let your newly harvested potatoes dry in a cool, dark, well-ventilated place for 1-2 weeks to toughen their skins.

Store cured potatoes in a dark, cool (35-50°F), and humid environment, like a root cellar, basement or refrigerator. Use breathable containers like burlap sacks or cardboard boxes to store them. Potatoes should last at least 3-4 months in the fridge, and up to 10 months when stored in the dark at 38°F (about 4°C).

How to Save Seed Potatoes for Next Year

To save seed potatoes, choose your nicest looking potatoes from a healthy, disease-free crop. Don’t wash your seed potatoes; just gently brush off loose dirt, and let them cure in a cool, well-ventilated area for a few weeks.

Wrap your seed potatoes individually in newspaper and store them in a single layer to prevent them from touching or crushing each other. Keep them in a cool, dark, well-ventilated place with temperatures between 35° and 40°F. Check them regularly for any signs of sprouting, rot or mold, removing any affected potatoes.

In early spring, unwrap them and chit them, just as you would any seed potato from a nursery.

How to Use Potatoes

Potatoes provide up to 30% of your daily vitamin C requirements and they have more potassium than a banana. Potatoes also have Vitamin B6 and calcium.

Potatoes can be used in a variety of ways, including baking them whole as a baked potato, frying them into french fries, roasting them with herbs and spices, mashing them for mashed potatoes, making them into crispy hash browns, or using them as a base for dishes like shepherd’s pie or potato salad.

Popular potato cooking methods include:

• Baking: Simply wash and prick potatoes with a fork before baking them in the oven until soft. Wrap them in aluminum foil and bake them on the grill or campfire!
• Roasting: Cut potatoes into wedges or cubes, toss with oil and spices, then roast in the oven for a crispy exterior. Garlic and rosemary are traditional on roasted potatoes, but any seasoning blend works with potatoes, including Indian, Mexican and more!
• Boiling: Boil potatoes until tender, then mash them for mashed potatoes or use them in soups.
• Frying: Slice potatoes thinly and fry them to make french fries. Duck fat, tallow and peanut oil are each particularly tasty for fried potatoes.
• Sautéing: Dice potatoes and sauté them with onions and peppers for a side dish.

Potato Recipes

• Creamy Ham and Potato Soup
• Easy Vegan Scalloped Potatoes
• Roasted Herb Mustard Potatoes

Photo credits: Deposit Photos