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Organic Potatoes::Mid Season Organic Potatoes::Red Norland Potato
Organic Potatoes - Growing InformationPrintable version of this page
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Types of Potatoes
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Potatoes (Solanum
tuberosum)are a hardy cool season crop in the the Solanaceae family which includes peppers, tomatoes, tomatillos,
eggplant and ground cherries. They are classified by early, mid, and late
season varieties, which refers to the days to maturity.
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Soil and
Nutrient Requirements
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Loose,
deep, well drained soil on the acidic side (pH 4.8-5.5) will grow the best
potatoes. Avoid heavy nitrogen applications, as this can lead to abundant
foliage but lower quality tubers that mature later. 140-150 lbs of
nitrogen/acre is average.
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Position
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Potatoes
need at least 6 hours of sunlight.
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Seeding Depth
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3-6"
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Plant Spacing
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12"
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Row Spacing
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30-36"
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When to Sow
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Potatoes
can be planted 1-2 weeks before the last frost date in spring. Small potatoes
(1-1.5” diameter) can be planted whole or larger potatoes can be cut into
pieces. Each piece of the tuber should have at least one eye (dormant bud).
Cut the tubers a day early in order for the skin to dry before planting.
Sprouts appear in 2 weeks.
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Other Considerations
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Hill
plants shortly after emergence and again 3 weeks later, making sure to cover
all exposed tubers to avoid greening, increase number of tubers, and promote
larger growth.
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Frost Tolerant
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Yes
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Drought Tolerant
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Potatoes need
consistent plentiful moisture for best yields and lowest incidence of scab.
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Heat Tolerant
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Potatoes
grow best when temperatures average just below 70 degrees.
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Seed Specs
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Fingerling-
20 pieces/lb avg; Full Size- 8-10 pieces/lb avg.
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Seeding Rate
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Fingerling-
50 lb/1000’, 900 lbs/acre, using 12” plant spacing, 30” row spacing. Full
Size- 80-100lb/1000’, 1,100-1,450 lb/acre, using 12” plant spacing, 36”
row spacing.
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Harvest
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New
potatoes can be harvested when plants begin to flower, around 7-8 weeks after
planting. Storage potatoes should be harvested no earlier than 2 weeks after
plants have died back.
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Storage
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Potatoes
should be left out in a dry dark place to cure. Store potatoes in burlap,
boxes, or crates in a dark, moist area at 38- 40ºF.
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Pest Info
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- The Colorado potato beetle
(CPB) can be a significant pest. While Bacillus thuringiensis var. tenenbrionis. is effective
against CPB and was formerly the easiest insecticide to use, the current
formulations have been removed from OMRI-A status due to difficulties
with assessing inert ingredients. Luckily there is a new addition to the
arsenal in the form of spinosad (such as Entrust™). Spinosad works
rapidly and effectively against CPB, as well as against corn earworm,
imported cabbage worm, codling moth, and several other difficult
lepidopterous pests. Ideally we will regain access to Bt so that these
two formulas can be used in rotation with one another to prevent
selection of resistant insects. Crop rotation, control of
solanaceous weeds, barrier trenches between old and new plantings, trap
cropping, use of straw mulch or row cover can delay or reduce CPB
pressure.
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Disease Info
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- Scab, caused primarily by the
bacteria Streptomyces scabies,
adversely affects grade and cooking quality, though not yield and
storage. Scab is most severe in dry weather, when bacteria antagonistic
to Streptomyces in the potato
lenticel dry up, allowing scab to more easily infect the plant. For
prevention, select scab-resistant varieties and maintain good soil
moisture.
- Late blight is severely
destructive, with the potential of total crop loss. Caused by the fungus
Phytophthora infestans, late blight is most
prevalent in moister climates such as the eastern regions of the U.S.
Symptoms of late blight include water-soaked areas at the leaf tips that
spread inwards and become dark brown and brittle after one or two days.
Symptoms can superficially resemble early blight, but are distinguished
by the fact that late blight obliterates the pattern of leaf veins where
as early blight does not. Action must be taken quickly if symptoms
appear. Because late blight is wind borne and spreads easily,
controlling its presence in your field can help nearby growers. Remove
and destroy infected plants and/or use fungicidal sprays such as oxidate
(such as Storox™, see Supplies) and/or copper hydroxide (such as
Champion WP™). Check with your organic certifier before applying
suggested compounds.
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