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Organic Pumpkin Seeds::Organic Jack O' Lanterns::Howden Pumpkin
Organic Pumpkins - Growing and Seed Saving InfoPrintable version of this page
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Types of Pumpkins
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Pumpkins (Cucurbita spp.)are long-season tender
annuals in the Cucurbitiacea
family, which includes cucumbers, summer squash and winter squash, melons and
gourds.
- Pie pumpkins are intended for
eating and have been selected for flavor, texture and density of flesh.
- Specialty pumpkins have
superior eating qualities in addition to their unique physical
attributes. Jack O’
- Lantern pumpkins are strictly
decorative, selected for shape, size, handle quality, uniformity, and
durability.
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Soil and
Nutrient Requirements
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Pumpkins grow
best in fertile, well-drained soil, with pH between 5.8-6.8. Sidedressing is
recommended one week after blossoming and again 3 weeks later, especially if
there are signs of deficiency. Nitrogen deficiencies cause yellowing, and
bronze leaves are a sign of potassium deficiency.
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Position
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Full sun
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Seeding Depth
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1/2-1”
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Seeding Rate
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2-3
seeds/18-36”, thin to one plant per spacing
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Plant Spacing
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For bush
varieties 18”, for vining 24-36”. Tighter plant spacing will result in yields
of smaller, but more numerous, fruit.
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Row Spacing
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Row
spacing: for bush/semi-bush and short vine types 6’, for vigorous vining
types use 9-12’.
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When to Sow
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Days to
maturity are from direct seeding, subtract 2 weeks if transplanting. Seeds
can be direct seeded after danger of frost has passed and soil temperature
has reached 70°F. Start transplants indoors 3-4 weeks before last risk of
frost. Optimal soil temperature for germination is 85-95°F.
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Other Considerations
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Black
plastic mulch and floating row cover can also be used to increase soil and
air temperature, as well as ward off cucumber beetles which eat young
seedlings and spread disease. Remove row cover when flowers open to allow for
insect pollination.
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Frost Tolerant
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The
pumpkins themselves can withstand a few very light frosts in fall, but should
be harvested before hard frost to avoid damage to the skin.
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Drought Tolerant
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No
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Heat Tolerant
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Yes
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Seed Specs
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C. pepo-
140-250 seeds/oz (175 avg), 2,300-4,000 seeds/lb (2,800 avg); C. moschata-
280-375 seeds/oz (310 avg), 4,500-6,000 seeds/lb (5,000 avg); C. maxima-
135-200 seeds/oz (155 avg), 2,200-3,200 seeds/lb (2,500 avg). M=1,000
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Seeding Rate
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Bush/Semi-bush-
10,000-15,000 seeds/acre, (C. pepo ~ 3.5-5.3 lbs., C. moschata ~ 2-3 lbs., C.
maxima ~ 4-6 lbs.) using 2-3 seeds/18” on 6’ centers. Vining- 3,500-5,000
seeds/acre (C. pepo ~ 1.25-1.8 lbs., C. moschata ~ .7-1.0 lb., C. maxima ~
1.4-2.0 lbs.), using 2-3 seeds/36” on 6’ centers.
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Harvest
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Harvest
by cutting stem near vine or at least 2-3” from fruit. Too many days of sun
on fruits after maturity will bleach handles and cause sun scald on the
fruit.
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Storage
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A short
or broken stem can lead to rot. Cure after harvest by keeping in a warm, dry
location for a few days then store at 50-55°F with 55-75% relative humidity
and good air circulation. Delicata and acorn squash do not need curing,
but will not store as long as other varieties.
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Pest Info
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- Striped cucumber beetles
cause feeding damage to the leaves, and often transmit bacterial wilt.
Larvae feed on the plant roots. Row covers can provide effective
protection, but must be removed during flowering to allow pollination.
Practice crop rotation and good sanitation to eliminate overwintering
habitat. Frequent application of kaolin clay and/or pyrethrum have shown
some effective control.
- Squash vine borer will cause
plants to look wilted even when moisture is plentiful. Slice open stem
and remove and destroy.
- Squash bugs can be controlled
by handpicking. Bury or compost plant residues at the end of the season.
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Disease Info
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- Powdery mildew, caused
primarily by the fungus Sphaerotheca
fuliginea, results in reductions in overall yields and quality of
harvested fruit. Powdery mildew does not overwinter in the northeast
(spores cannot withstand cold and cannot persist in the absence of host
tissue) but blows north every year from southern states where crops are
planted earlier. Powdery mildew is difficult to control with fungicide
applications, even conventional ones, because the fungi multiply rapidly
and attach to the undersides of leaves where they are difficult to reach
with sprays. Many newer pumpkin varieties have been developed with
tolerance to powdery mildew (PMT). Plants can still become infected but
the symptoms are usually much less severe.
- Pumpkins are also subject to
several fruit rots, of which the most common is probably black rot,
caused by the same fungus that causes gummy stem blight (Didymella bryoniae). Recent
research indicates that control measures for powdery mildew, including
the use of PMT varieties, is also effective against black rot. In the
case of black rot, the pathogen can be seed-borne and survive in crop
residues.
- Scab – Avoid wetting foliage
and give plants plenty of space for circulation.
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Seed Saving
Instructions
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Insect pollinated. Take caution unless you are hand
pollinating, as many pumpkin varieties are the same species as many summer
squash and winter squashes. Different varieties of the same species need to
be isolated by 1/4 mile to prevent cross-pollination. Barriers such as tree
lines, woods or buildings existing between the fields can reduce this
distance. Treat pumpkins the same as usually done for winter storage. After
all squashes have reached this stage, harvest and let them sit for a period
of after-ripening for 3-6 weeks or up to several months. Remove the seeds,
rinse in water and dry. Use of a 1/2" and 1/4" screen can help with
cleaning. Squash seeds remain viable for 6 years under cool and dry storage
conditions.
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