Purple Chief Potatoes

Planting:

Tolerant of cool soil and frost, potatoes can be planted in late spring. Remove tubers from storage and warm to a temperature of 50-60 degrees F, to enhance sprout formation. Small tubers (golf ball size) may be planted whole. Larger tubers can be cut into pieces weighing about 2 ounces each having at least 1-3 eyes. Seed pieces can be planted immediately after cutting but will generally sprout and show better resistance to decay if, after cutting, are left in a cool, moist room with good ventilation for 3 days. Sow seed pieces 3-4 inches deep. Leave 10-12 inches between plants in rows 2-3 feet apart. Closer plantings can result in better yields, but with smaller potatoes. Do not plant directly from cold storage.

Growing:

Grow in full sun with soil pH of 5.5-6.5. Potatoes are heavy feeders and require deep fertile soil with good drainage. Mineral soils are best. Apply plentiful amounts of compost and well-rotted manure. Fresh manure will promote development of scab organism. Lime should also be avoided at planting time. Maintain even moisture as interruptions in moisture will cause irregular growth spurts resulting in rough, knobby, malformed or cracked tubers. Hill plants when they are 1 foot tall, by hoeing up 6-8 inches of soil around the plant.

Harvest:

Early potatoes can be dug when tubers reach a usable size. This is often 2-5 weeks after flowering. Storage crops should be left in the ground until light frosts or natural decline cause the tops to wither.

Pests & Diseases:

Blight is a fungal disease which can cause potatoes to rot in storage. The disease appears as dry brown lesions with fluffy white mould on the undersides of the leaves. Use a sulfur or copper fungicide to help prevent the onset of the disease. Control potato beetles with Rotenone or by hand picking.

Companions:

Bush bean, cabbage family, corn, parsnip, peas.

Storing:

If you are growing potatoes for winter food storage, let the tubers develop fully in the ground. Mature potatoes are less likely to bruise when harvesting than immature potatoes and will last longer in storage. Potatoes are finished growing when the foliage starts turning yellow. Stop watering at this point and let the foliage die back. During this time, the skins of the potatoes will thicken and toughen up. This will help protect the tubers from damage when they are harvested.

Harvest the potatoes on a warm, dry day after a period of little or no rain. Digging by hand is the best way to avoid damaging the potatoes. Use a digging fork to loosen the soil beneath the potatoes. Then sift through with your hands and pull out the tubers. Place your potatoes carefully in buckets or bins. Try not to bruise or damage the skin or the potatoes will not last long in storage. Consume poor quality potatoes first and keep blemished tubers separate from your storage potatoes because they are more likely to rot, risking potential to infect other tubers.

Curing your potatoes will help heal small wounds and toughen up the skin to form a protective shell that extends the storage life. To cure your potatoes, simply spread out the unwashed tubers in a single layer in shallow boxes lined with newspapers. Cover the trays with a dark cloth or towel to eliminate light but allow air to circulate. Let the potatoes cure for several weeks in an area that is between 50 to 60˚F. 

Ideally, potatoes should be stored in a dark, well-ventilated area at 40˚F to 42˚F (4°c). The relative humidity should be around 95% to prevent the tubers from drying out. The ideal storage area for potatoes is one that is:
Dark: Exposure to light and stress will trigger chlorophyll production, forming solanine. Chlorophyll will turn the tuber green, but solanine will give potatoes a bitter taste, and can cause illness if eaten in large quantities.
Ventilated: Store in an area with good airflow so they can use oxygen and give off carbon dioxide while in storage. A small fan will work for areas with no air movement.
Cool: Keeping potatoes cool slows the growth of disease organisms that will cause the tubers to spoil. 40°f to 42°f (4°c) is the sweet spot. If the temperature is too cold, the starch in the potatoes will convert to sugar and turn tubers dark. Warmer temperatures will also trigger the potatoes to sprout.
Humid: Potatoes contain 80% water and need to be stored in a damp area to prevent the potatoes from drying out. 95% is the ideal humidity level but understand that this may not be achievable for most home environments. You can increase the humidity using a humidifier, or by placing large pans of water near your air source.
Suggested home storage locations include an unheated basement, spare closet, shed, crawlspace, or garage. Any area you choose should be insulated to protect the potatoes from freezing temperatures.

Store potatoes separate from apples and other fruits. These give off ethylene gas that can cause your potatoes to sprout prematurely.

Every few weeks, look through the boxes to remove any potatoes that may begin to rot. Usually, you can tell by the scent if there is one in the box. If you notice a musky, sour dirt smell, you should look through the box to remove the rotten potato before it infects the others.
Under the ideal storage conditions, potatoes can remain fresh for 3 to 6 months or longer. Sprouted potatoes can be planted in spring, if they look healthy, and the previous season was disease free. Always start the planting season with fresh, disease-free seed potatoes.