Home vegetable gardening has become so popular lately even the kids are getting excited about planting and digging (well, maybe)! What a great family project to work on together and also what great exercise! We hope our little brochure will help you achieve a bountiful harvest of potatoes!

Yes, it’s true, supermarket potatoes usually cost quite a bit less than certified seed potatoes. But no matter how much you may seem to save, it’s not advisable to use supermarket potatoes for planting. Eating potatoes are almost always treated with a sprouting inhibitor for a longer shelf life. When the potatoes finally do sprout, the chemical continues to retard shoot growth. The consequence will be low yield! Purchase certified seed potatoes for the best harvest.

Preparing to Plant: All tubers the size of an egg should be planted whole. Ones this size are highly desirable. Cut up large potatoes into pieces before planting, using a clean, sharp knife. Remember, however each piece should weigh at least 2-4 ounces and must contain two or more strong eyes. To avoid shriveling avoid direct sunlight. This will also weaken your potato.

Soil Preparation: The ideal potato soil is deep, light and loose, well-drained yet moisture retentive. Most potatoes are very aggressive plants, and are able to take full advantage of such soil. Fortunately, for most of us, the potato is also very adaptable and will usually produce quite well for the home gardener, even where soil is less than perfect.

All soils, be they ideal, too heavy or too light should be deeply tilled before planting. Humus is important. It lightens and aerates heavy ground while it increases the moisture holding capacity of your soil. Potatoes do best in slightly acid soil with a pH ranging from 5.5 to 6.5. As far as NPK goes, potatoes need will-balanced nutrition. We recommend some fertilizer, but not too much. Potatoes given too much nitrogen grow lots of leaves but few tubers, while too much potassium and your tubers will have less protein.

Planting: Seed potatoes can rot in cold, waterlogged soil. Optimum soil temperature for good growth ranges from 55⁰ F. to 70⁰ F. The earliest we recommend planting is 6-8 weeks before the average last frost date (April 15). If frost burns the vines the tubers will make more sprouts, but each time this happens the final yield gets later and smaller. Generally about 10 days to two weeks before the last frost date is fine.

The width between rows and overall plant spacing is determined by the size of the garden, and the amount of irrigation needed. Usually around three feet between rows is sufficient for cultivation and hilling. Dig a trench about 6-8 inches deep. They should be spaced about 10-14 inches apart. Using a rake, cover the seed potatoes with 3-4 inches of soil - do not fill the trench completely.

Hilling: Hilling is crucial to growing many large potatoes. Sprouts will emerge in about two weeks, depending on soil temperature. When the stems are about eight inches high, gently hill the vines with soil from both sides of the row. Leave about four inches of the vine exposed. Most all varieties will form above and close to the seed piece that was planted. Another hilling will be needed in another 2-3 weeks, and yet another as well two weeks after the second. On subsequent hillings, add only an inch or two of soil to the hill. Remember to keep an eye on the plants later in the season and make sure there is enough soil on top of the forming potatoes so that they don’t push out of the hill and get exposed to light (this will turn them green). When hilling, make sure the hoe blade is kept shallow to avoid damaging the roots and tubers.

Watering: As always watering depends on many factors. Least of which is the amount of rain we receive, how well your soil drains, and your particular irrigation system. Most potatoes have a very aggressive root system and can cope with surprisingly dry soil. There is some evidence that potatoes grown in dryer conditions actually have a higher protein content. Remember to give them lots of elbow room to grow and keep those weeds pulled!

Fertilizing: After emergence and until blooming ends, we highly recommend foliar spraying every two weeks with fish emulsion or a good liquid fertilizer. You can’t beat foliar sprays for ease of application, and the plants really respond with a burst of vine growth that will result in a higher yield. Spray in the morning while it’s still cool and the dew lingers on the leaves. This way all the fertilizer is absorbed. Once the vines are in full bloom additional fertilization is pointless and may even harm the flavor of the potato.

Insects: To have vigorously growing, healthy vines you must avoid insects. While plants are leafing out they can generally withstand some insect presence, however once vine growth has stopped it can become a much more serious problem. The Colorado Potato Beetle is the most widespread and destructive potato pest. Both adults and larvae feed on leaves and stems, sometimes defoliating entire plants. Bacillis thuringienses (Bt) is an effective botanical control, but unfortunately, only for the larvae. The adults are not harmed at all! Bt is entirely nontoxic to humans and other animals. If adult beetles are causing trouble try 5% Rotenone dust or a Pyrethrin spray. Diazinon and Sevin are good chemical controls.

Diseases: Bacterial soft rot is a disease that causes potatoes to become soft, watery, and slightly granular. This is common where potatoes have been bruised or wounded or when soil temperatures are high. A foul odor is also a sign of bacterial soft rot. There is no known chemical control, however planting certified disease-resistant potatoes does help. Keeping your equipment clean and not applying excessive amounts of nitrogen seem to inhibit onset of bacterial soft rot. Avoid wounding and washing potatoes prior to storage.

Harvesting: Normally, seven or eight weeks after planting, the earliest varieties are blossoming. Dryish soil is definitely an advantage when harvesting; the tuber comes up a lot cleaner and with much less effort. After the tops are dead leave the tubers in the ground for two weeks to “cure,” while the skins toughen. Protect the tubers from scuffing and bruising during harvest and storage. Harvest in the morning hours while it is still cool, not when the ground and the air are hot. If hand digging, place the fork outside the hill at first and lift the hill from outside so as to avoid stabbing the potato. If the soil is wet let them air-dry for a few hours before gathering them.  Do not put cut or damaged tubers into a sack with good ones; they will rot and also rot other potatoes with them.

Storage: Potatoes keep best in the dark at 36⁰ to 40⁰ F, with enough humidity and air circulation so as not to dry out. Light and warmth promote sprouting and will also turn the potatoes green. Cold potatoes bruise easily so handle them carefully. Burlap sacks, slotted crates, baskets, or wooden bins work well for storage over the winter. Partially heated garages, sheds, closets on outside walls, porches or unheated back rooms can all be cool, dark sites good for keeping potatoes. Keep the area as cool as possible but protect from freezing.

Choose the Right Seed Potato