Potatoes, Earth's Treasure 

A bountiful and delicious potato harvest.

Plant one potato and harvest many. That’s the thrill of growing this delicious veggie whether it be boiled, roasted, fried or mashed. The Incas grew them as early as 3,000 BC and were there major source of carbohydrates and vitamins: C, B6, potassium, thiamin, niacin, fiber, iron, and they even contain protein. The mighty potato is such an essential source of food for so many and for so long, it is featured in the documentary ‘Botany of Desire’. They extol the origins and attributes of this starchy tuber as well as other important plants. To check out the video click here.
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A garden fork is a useful tool to harvest your loot. Wait for the stems to die back first.

Just a few plants produces high yields.

Potatoes are members of the Nightshade family, which also includes peppers, eggplants (aubergines) and tomatoes. Taters originate from underground tubers. These tubers are actually stems. They contain chlorophyll and that’s why spuds turn green when subjected to light. Potato ‘eyes’ are really the beginnings of stems and leaves, which makes propagating them very easy.

Potato 'eyes' are actually stems that are ready to grow.

A potato plant grown from one seed potato.

Potatoes are actually underground stems, that's why they turn green when exposed to sunlight.

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When to Plant

Plant potatoes anytime from March to the end of May. For early spring planting, wait until the ground isn’t too cold and wet so they don’t rot. Don’t plant if the soil drips water when squeezed. Soil temperature should be at least 7.2°C (45°F). Warmer soil encourage faster growth.  Purchase seed potatoes as they sprout quickly and are certified disease free, unlike ones from the produce department in the grocery store. 

Purchase seed potatoes as they are certified disease free and sprout readily.

Preparing the Soil

Spuds must have an acidic soil that drains well. Mix in compost, but don't add lime.

Grow potatoes where beans, peas and other legumes where previously planted.

Potatoes prefer an acid soil with a pH from 4.5 to 5.5. Select a location that receives at least 6 hours of direct sun a day. A sandy well-drained soil is best, but they are pretty soil tolerant as long as the soil isn’t soggy. Soil that’s too wet promotes rotting and crop failure. An addition of an inch or two of compost, SeaSoil, triple mix and/or com posted manure mixed into the soil is beneficial. Do not lime the soil as it promotes potato scab.

​Plant potatoes where peas, beans or other legumes were grown the previous year or after an early crop of peas has been harvested. Don’t pull them out by their roots as that’s where the nitrogen has fixed itself onto the legumes’ roots. Just cut them off at their base, then plant the spuds. Since legumes fix nitrogen within the soil it provides the potatoes with nitrogen. 

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​Preparing Potatoes to Plant: Chitting Potatoes

To 'chit' taters encourages earlier harvests and higher yields. Just place seed potatoes upright in a egg carton.

The ‘eyes’ or sprouts that dimple a potato are the beginnings of stems that quickly develop into a robust plant. To encourage the eyes to grow, place the potatoes upright in an egg carton with the end with most of the eyes facing up. If you have many seed potatoes, place them upright in crates with slatted bottoms. This process is called chitting and although it’s not necessary, harvests are bigger and earlier than just planting potatoes in the ground. Place the egg cartons with the potatoes in front of a sunny window. Once shoots from the eyes are about ¾in-1in long, they are ready to plant. For fewer but larger potatoes, keep only 3 or 4 of the shoots and rub off the rest.  

Planting Spuds

Either plant whole potatoes or slice them in half. Make sure each half has a few eyes.

Allow cut potatoes to dry for 2 to 3 days and dust the cut end with cinnamon before planting.

Plant them whole potatoes or cut them in half. As long as the piece have a few eyes, they are viable. Cut the potato 2 to 3 days before planting to prevent rotting. Before planting, dip the cut end into some cinnamon as it is a natural fungicide.
 
Plant each potato 3 to 6 inches deep trench about a foot apart – eyes side up! Cover with 3 to 4 inches of soil. Hill the extra soil up along the trenches. Don’t water until they emerge from the soil then keep the soil evenly moist. If the soil dries out, the plants will die back affecting the harvest quality and quantity.

Place seed potatoes in a trench eyes side up.

Don't water until their leaves emerge.

The Importance of Hilling

Hill spuds with soil or straw as they grow to encourage higher yields.

Potatoes grow along their stems and above ground exposing them to sunlight, which turns them green. Adding soil over top of the plants prevents this and makes more spuds.

As the plants grow, pull up soil around the base of each plant. Continue to hill the soil around the plants as they grow. If you don’t, potatoes will poke their way through the soil and will turn green because they are exposed to the sun. Green potatoes contain a poisonous substance called solanine, which upsets tummies. This is why you have to hill the soil around potatoes as they grow. Green spuds are still edible as long as you remove the green parts. Luckily the green is just within the skin. 

Harvesting

Potato flowers indicate that tender sweet new potatoes are ready to harvest.

Harvest new potatoes by reaching in a pulling out a few unless you want to harvest the entire crop.

New Potatoes: For ‘new’ potatoes, harvest when the plants are flowering. Either dig up the entire plant or reach in to pick out a few.
Main Crop Harvesting: 
Stop watering once the stems have withered then wait 3 weeks to harvest. This process hardens their skins so they store better. Select a dry day to dig them up using a garden fork. Brush off any soil -  don’t wash them as it encourages rotting. Cure in a cold, dark and frost free place with good ventilation for a couple of weeks.

To toughen up their skins even more, cure them by placing them in cardboard boxes or on shelves covered with newspaper in a cool location. Remove any spuds that are damaged or diseased. For prolonged storage, select a cool room, 2-4 C (35 to 40 F) such as an unheated basement or garage. A refrigerator works well, if there's enough room. Keep them away from light and frost. 

Pick a dry day to harvest potatoes.

Don't water plants after the stems wither. Wait three weeks then harvest. Place in a dry place.

Cure potatoes in a dry cool spot and cover to prevent the light from turning them green.

Growing Potatoes in Containers

I kept filling the laundry basket with soil as the potatoes grew up inside.

You don't need a garden to grow potatoes. This 5 gallon nursery pot was quite productive.

The container produced healthy numerous spuds.

​Yes, it is doable! Potatoes are surprisingly easy to grow in containers. I have used big black 5 gallon nursery pots and as an experiment, a laundry basket – and both methods work well.
 
Start off with a pot with drainage holes. Add about 4 inches of soil to the bottom of the container. Add your seed potatoes placed 4 inches apart or more. Cover them with a couple of inches of potting soil. Add more soil as they grow. Treat them the same way as ones planted in the ground.  

Potato Scab

Potato scab doesn't affect the taste of the potato, just peal it off before cooking.

Symptoms appear on the potatoes only in the form a scab-like growth. This disease is caused by soil that has a pH higher than 5.2. To lower pH, add sulfur or dust each seed potato before planting. Don’t add lime to the soil before or after planting as this increases pH. Since this disease also overwinters in the soil it’s important to clear the garden bed from all potato foliage and parts after harvesting. Plant certified disease free seed potatoes. Russet varieties have a better tolerance to scab. Although scab is unsightly, it does not affect the taste of the potato, but I do suggest you peel them before cooking. 

Colorado Potato Beetle

Colorado potato beetles are potatoes worst enemy.

Look on the undersides of the potato foliage for their eggs and rub them off.

​Symptoms first appear as irregular holes at the edge (margins) of the foliage. As feeding progresses the leaves are skeletonized so only the veins remain. The larva and the adult beetle feed on the leaves of potatoes as well as other members of the nightshade family: pepper, tomato and eggplant.  
 
This 1 cm long beetle are easy to spot and to identify. They have five brown stripes along their amber coloured backs. Their larva’s head is black atop a dark red body. The adults overwinter in the soil where the potatoes were harvested. They later emerge in spring where they feed and lay hundreds of orange or yellow eggs in early July. The eggs hatch in 4 to 15 days. The larvae has two rows of dark brown spots along their backs. They feed on the foliage and go through 4 stages of growth until the measure 8 mm long. During the last phase they drop and burrow into the ground and pupate. After 5 to 10 days, the adult emerges to feed and to mate. This whole process takes about 21 days.
 
The easiest way to control these beetles is to hand pick them off the plant and depositing them into a cup of salty water. To kill the larva use the bacterium Bacillus thuringiensis specifically for Colorado potato beetle larva. Products made from Neem will deter the insect from feeding. Try a tea made from tansy leaves and flowers and spray on the plant while the insects are present. And finally, mulch with straw as soon as the potato leaves emerge from the soil. The mulch hinders the beetles from finding the spuds and increases the beetle’s predators.  

The beginnings of beetle damage.

The larva and beetle feed on the foliage.

Rotate Your Crops!

Potatoes won't be planted again in this bed for a few years.

In the meantime, I will use the bed for companion planting.

​Finally, rotate your crops yearly. All members of the nightshade family are prone to the same diseases and insects and use the similar nutrients within the soil, therefore don’t plant potatoes where tomatoes, peppers, eggplants and especially potatoes grew the year before or the year before that. It’s best to wait 4 years to plant in the same spot. Crop rotation is an important part to reduce disease, insects and increase soil fertility. For more on crop rotation click here.