One Potato, Two Potato

Marlene Spinoza
Adams Count Master Gardener

Planting potatoes is one of the most fun and "filling" experiences in vegetable gardening.

Potatoes do not require any more care than other vegetables but are rather particular about soil needs and a good control of diseases and insects. Potatoes grow best in soil that is well drained, loose and high in organic matter. Soil that is too sandy, rocky, or clayey is not good for potatoes. You may need to amend the soil by adding compost, manure or other ingredients preferably the fall before you plant. The soil should be tilled at least 10 inches deep or double shoveled and raked. The pH for growing potatoes is 5.5 to 6.0 which is lower than most vegetables, as potatoes favor a more acid soil.

A soil test can provide information to help your garden production. If a soil test is not available and the garden has been well maintained for a number of years, add a 1-1-1 fertilizer such as 10-10-10- at a rate of 2.5 to 3.0 lbs. per 100 sq. ft. or half that amount of 20-20-20 for each 33 ft. row. If this is a new area, use a 1-2-2 ratio such as 5-10-10 at 1.4 to 1.5 lbs. per 100 sq. ft. When planting a large area, side dress rows in bands, 2 inches from tubers. Fertilizing this way saves fertilizer and also does not fertilize weeds between rows. Last yearís potatoes or grocery store potatoes should not be used as seed potatoes. Use only certified seed potatoes which are state inspected.

Potatoes need to be purchased 2 to 3 weeks before planting in order to season them. Spread out in a shallow box in an area with sunlight where the temperature is about 70 degrees. The potatoes will form sprouts which will encourage quick emergence when you plant them. About 5 to 7 days before planting, cut potatoes length wise into block-like pieces having at least 2 eyes, allow the cut surface to heal over and toughen up during those days. These steps will help prevent rot and disease. Plant potatoes in spring when soil temperatures reach 48 to 50 degrees or when a warming trend is predicted.

If the spring is wet, mounding up the sides of rows or plants will help drainage. Plant potatoes 3 to 4 inches deep to encourage early emergence. When small clusters of leaves emerge, more soil can be added at sides when cultivating. In case of frost, cover with straw or newspapers.

Potato rows should be about 3 ft. apart, and the seed potatoes placed 8 to 10 inches apart. If there is excessive rainfall, a side dressing may be required at about 4 weeks. Sodium nitrate 33-00 or a couple of lbs. of general purpose fertilizer is recommended. When planting potatoes, applying too much manure and lime can cause a severe scab problem. If possible, apply these items the fall before you plant potatoes. Flowering potato plants do not indicate tuber development as tubers actually develop 1 to 2 weeks before plants flower. A cool spring is great for potatoes as it helps expand the starches in the tubers. Potatoes need 1.5 inches of water per week, more during dry spells. Do not water from above but by drip irrigation or soaker hose.

Weeding potatoes is essential for disease and pest control; however, you can control weeds using plastic mulch. The mulch can be cut with a bulb planter every 12 inches and hand planted in rows about 18 inches apart. Drip irrigation works well with this method of planting.

Potatoes can get Early Blight which is small circular brown spots with a target like spot in the middle. This will kill plants and is caused by plant debris overwintering in the bed where you plant. Plant rotation is extremely important with potatoes. Do not grow in the same bed for 4 years. Clean up the garden in fall. Late Blight can happen anytime during the season. Often the source is infected tubers from the previous season. The leaves will have brownish purple lesions at the tips and can also have white mildew at these lesions. Both Early and Late Blight can be helped by using a foliar fungicide.

Common Scab is caused by a bacteria that can be in the soil for a long time, even when potatoes are not planted in that spot. The main cause is decomposing material such as vegetable matter not cleaned up. Using an acid based fertilizer can sometimes help or find another place to plant. Black Leg can develop when the weather is too wet and cool. It's a black lesion that forms on the upper stem. Healing your cut potato pieces before planting can prevent this.

Virus diseases can be spread by insects and by not using certified seed. The plantís growth will be distorted and the foliage can be mottled in appearance. These diseases can kill potatoes. Insects like Flea Beetles, Colorado Potato Beetles, Corn Borers and Grubs can attack your plants. Keep these insects under control and your crop will be safe. Look up these insects online or in the library so you can recognize them when they come to visit. Amazingly if you rotate your crops every 4 years, you will not have major problems with these pests. Wire worms can also be a problem tunneling into your tubers; avoid them by not planting potatoes in areas that are previously waste areas or grassy areas.

The potatoes I've had the most success growing here are Dark Red Norland ,Yukon Gold and Superior. Growing potatoes is exciting especially when harvest comes, but that's another article.

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