Cultural Practices

Types and Varieties

Summer squash varieties have several types with varying colors and shapes. They are harvested multiple times throughout the season (every 1 to 3 days).  Winter squash have an almost endless array, from very large to very small and are harvested once at the end of the season.  Pumpkins also run the gamut from small to extremely large.  They come in white, orange, and even a deep red.  Of the cucurbits, gourds are most known for their colors and shapes.  Many bear names that reflect their appearance: crook-necked, winged, crown-of-thorns.

Pumpkin, Squash, and Gourd Varieties

Pumpkin, Squash, and Gourd Varieties
Miniature Pumpkin Yellow Summer Squash
Baby Boo Cougar - ZYMV, PRSV
Bumpkin Early Prolific Straightneck
Little October Enterprise
Wee-B-Little Fortune
Apprentice Gentry
   
Small Pumpkin (2-6 lbs) Zucchini
Baby Pam Cashflow - ZYMV
Cannon Ball - PMT Payroll - PMT, WMV2, ZYMV
Chucky Leopard - PRSV, WMV2
Hybrid Pam Spineless Beauty 
Mystic Plus - PMT Zucchini Elite
Neon Sebring (golden) - PMT
Hijinks Golden Glory (golden) - PMR, WMV2, ZYMV
Prankster - PMT  
Rockafellow - PMT Scallop and Speciality Summer Squash
  Patty Green Tint
Medium Pumpkin (6-20 lbs) Peter Pan
Challenger - PMR Starship
Diablo Sunburst
Gladiator - PMT Eight Ball
Magic Lantern - PMT One Ball
Merlin - PMT Zephyr (bi-colored)
Mystic Plus - PMT Bush Baby (striped)
Magician - PMR, ZYMV  
Sorcerer Winter Squash - small, Cucurbita pepo
  Carnival (delicata/sweet dumpling)
Large Pumpkin (>20 lbs) Delicata
Autumn King Honey Bear (acorn hybrid) - PMR
Big Rock Royal Ace (acorn hybrid) - PMT
Cronos - PMT Taybelle PM (acorn hybrid) - PMR
Expert  
Gladiator Winter Squash - buttercup/kabocha, C. maxima
Gold Medal Ambercup
Gold Medallion Bon Bon
Howden Burgess Buttercup
Mustang - PMR Sunshine
Phatso III - PMR Sweet Mama
  Red Kuri
Exhibit/Giant Pumpkin  
Atlantic Giant Winter Squash - hubbard types, C. maxima
Prizewinner Boston Marrow
  Blue Hubbard
Ornamental/Specialty Pumpkin Ballet
Bunch O'Warts  
Knucklehead Winter Squash - spaghetti, C. pepo 
Goosebumps Tivoli
Rascal Vegetable Spaghetti
   
Ornamental Gourds Winter Squash - butternut, C. moschata
Autumn Wings Avalon
Birdhouse Butternut Supreme
Crown of Thorns Metro PMR - PMR
Galaxy of Stars Waltham
Goblin Eggs  
Lunch Lady Winter Squash - processing
Spoon Golden Delicious (C. maxima)
Snake Maxim (butternut)
   

Resistant or tolerant to: PRSV: papaya ringspot virus, WMV2: watermelon mosaic virus-2, ZYMV: zucchini yellows mosaic virus, PMR: powdery mildew resistant, PMT: powdery mildew tolerant

Soil Fertility

Apply lime according to soil test results to maintain soil pH at 6.5 to 6.8.  Pumpkins and squash prefer well-drained soil, preferably sandy loams with high organic matter.  Do not plant squash or pumpkin until daily soil temperatures are at least 60°F.  Gourds can be grown in a wide range of soil types but mature earlier and color better on sandy soils or sandy loams that drain well and warm up early in the spring.

Plant Nutrient Recommendation According to Soil Test Results for Pumpkin and Squash

PUMPKINS AND SQUASH

Nitrogen (N)* Lbs per acre

Phosphorus (P) Lbs P2O5 per acre

 Potassium (K) Lbs 2O5 per acre

Soil Test Results

 

Very Low

Low

Optimum

Above Optimum

Very Low

Low

Optimum

Above Optimum

Broadcast and Incorporate(Transplants)

50

110

60

0

0

160

110

0-40

0

Band-Place when Direct Seeding**

20-40

40

40

0-40

0

40

40

0-40

0

Sidedress When Vines Start to Run***

40-50

0

0

0-0

0

0

0

0

0

TOTAL RECOMMENDED

110-140

150

100

0-40

0

200

150

40-80

0

*See Plant Nutrients for information on nutrient management and application.

**Total N and K2O in the band should not exceed 5.5 lb./1000' of row. Banded P2O5 may not be of benefit in warm soils.

***Sidedressing may not be necessary when using plastic mulch, or if organic matter can supply sufficient N; repeat sidedress in 2 to 3 weeks

Planting

Seeding rate: Winter squash and pumpkins at 2 to 4 lb/A; 0.5 to 2 oz/100 ft row.  Summer squash at 4 to 6 lb/A; 1 to 2 oz/100 ft row.  Fungicide-treated seed recommended. 

Spacing: Bush varieties should be planted 18" to 24" within rows and 4' to 5' between rows.  Vining varieties should be planted 2' to 6' between hills (1 to 3 plants/hill) and 6' to 12' between rows.  Spacing will vary with cultivar and size of vine.  Pumpkin fruit size is greatly influenced by spacing.  The closer the spacing, the smaller the fruits, even on large-fruited types.  Growers should experiment with both bush and vine types to determine the most desirable fruit size for a particular cultivar under the conditions of individual farms.  Plant seed 0.75" to 1.25" deep, depending on soil texture and moisture.  Sow enough seed to ensure a stand that may be thinned later. Mice especially like germinating seed.  Some growers have seeded 3 times in the field before achieving the desired stand.

Gourd seeds can be purchased as a mix or can be ordered from some seed companies by type or form (warted, spoon, crown of thorns, etc.). Seeds can be saved to develop mixes but plants must be isolated from other cucurbits. Check days to maturity to be sure that growing season is long enough.

Squash and pumpkins are frequently direct seeded, but for early markets it may be profitable to transplant, especially expensive hybrid seed.  Bare ground and plasticulture systems can be either direct seeded or transplanted.

Transplants may be used to ensure uniform or complete stands, increase yield and to increase the likelihood of early harvest.  Prior to transplanting, the plants can be hardened by placing them outside in a protected location. Seed about 2 to 3 weeks before transplanting into the field.  It is common to transplant into the field at the 3 to 4 leaf stage, but some growers get better survival by setting out younger plants (cotyledon to first true leaf stage).  Transplants are quite subject to root injury and should be handled carefully with as little disturbance as possible.  Those transplanted from the greenhouse before the frost-free date should be covered with hot caps or row covers or protected with irrigation (see Irrigation, page 25) to avoid freezing injury.  Transplanted pumpkins and squash generally have reduced root systems compared with direct-seeded plants.  Transplants should be used only in irrigated fields.

Field Culture

Pumpkins can also be produced using a strip-till or no-till system.  In such reduced-till systems, seeds are usually planted into the stubble of a killed cover crop or harvested small grain.  Reduced-till systems provide erosion control, help retain soil moisture, improve soil structure, reduce weed and disease pressure, provide cleaner fruit at harvest and may facilitate planting and harvest operations during wet weather.

Using black polyethylene (plastic) mulch offers several advantages to growers. Black plastic mulch increases the soil temperature earlier in the growing season and conserves moisture. It also reduces soil compaction and crusting, ground rot of fruit, fertilizer leaching, drowning of crops, evaporation, and competition from weeds.  These benefits promote increased quality and quantity of fruit yields, as well as earlier production, especially when used in combination with transplants.  Although using mulch will increase production costs, increased profits from earlier and larger yields offset those costs.  Drip irrigation systems must be used with plastic mulch.  Place drip tape down the middle of the bed, buried 2 to 3 inches deep.  In addition, growers can plant multiple crops (double-cropping) into the plastic mulch provided care is taken to avoid excessive damage (tears, holes, etc.) to mulch.  With summer squash, double rows of plants within each row can be used.  Gourds can be grown on the ground or can be trained to grow on a trellis, fence or arbor.  For commercial production, they should be grown in rows or hills like squash and pumpkins. 

Pumpkin and squash require bee activity for good fruit set.  Fruit set in winter squash and pumpkin takes place largely over a 2 to 3 week period, hence the importance of bees.  Inadequate pollination results in poorly shaped fruit, as well as excessive blossom drop.  One hive of bees per acre is recommended.  If honey bees are not available, bumble bees are a reliable alternative and are commercially available.  Since bees can carry pollen for a mile or more, isolation of fields from other types of squash or pumpkin is rarely possible in the New England area.

Several factors other than bees and pollination may affect fruit set.  Pumpkins and squash have separate male and female flowers.  The numbers of female flowers, which produce fruit, is adversely affected by prolonged periods of high temperatures of (7+ days above 90°F day and 70°F night), dry conditions just prior to and during bloom and excessive shading from the plant canopy.  Sometimes low yields associated with lack of female flowers can be avoided or minimized by making several plantings over 2 to 3 weeks, planting several varieties, timely irrigation, avoiding excess nitrogen and spacing pumpkins farther apart to help reduce shading.

Harvest and Storage

Summer squash. Summer squash should be harvested as immature fruit approximately 7" in length. This may require a 1 to 3 day picking interval. Care should be taken not to damage the tender skin. Fruit may be harvested by cutting the stem with a knife or by twisting it from the plant. Cutting with a knife can transmit virus. If virus is detected in the field, fruit should be harvested by twisting from the plant.

Summer squash can be damaged from 3 to 4 days exposure to temperatures of 32°F to 40°F and 90% or higher relative humidity. This is commonly referred to as "chilling injury." If storage is required, hold at 45°F to 50°F and at 90% relative humidity for up to 2 weeks. Summer squash should be marketed as soon as possible.

Winter squash and pumpkin. For winter squash, good yields of smaller varieties are 5 to 7 tons per acre or 2000 to 4000 fruit.  The large types (fresh market) may yield up to 10 to 30 tons per acre or 1000 to 2000 fruit. Winter squash and pumpkin are not normally harvested until the rind or skin is completely hardened. If necessary, pumpkins can be harvested as soon as some color is present. If possible, pumpkins that have reached full color should be stored under cover to protect them from chilling injury from temperatures below 50°F and from disease. Fruits are easily damaged by rough handling. Do not permit fruits to be exposed to 32°F, as this can promote storage problems.

Winter squash should be well matured for storage, and free from injury or decay. A 10 to 20 day curing period at 80°F to 85°F before storage is often recommended for squash showing any surface damage or with skin that has not hardened, but is not consistently beneficial for squash showing no damage or that is well matured. All winter squash should be stored between 55°F and 60°F. Research has demonstrated that disease is minimized at 60°F and at 50% to 75% relative humidity. Chilling injury occurs any time the temperatures fall below 55°F, either in the field or in storage. Damage is cumulative; injury increases as temperature decreases and/or length of chilling time increases. Such squash is likely to break down in storage. 

Pumpkin can be stored in good condition for 2 to 3 months at 50°F to 55°F and 70% to 75% relative humidity. Hubbard and butternut squash can be kept 6 months or more, acorn 5 to 8 weeks and buttercup 2 to 3 months or more. Squash should not be stored with ethylene producers such as ripe apples or pears since squash will turn color, become stringy and decay. It is important to keep squash dry and maintain good air circulation.

Gourds. Gourds should mature between late summer and the first fall frost. Harvest fruit when the stems become dry and the skin is hard. Discard any fruit which is bruised, cut, or showing symptoms of disease. Wash gourds in warm, soapy water to remove any soil and reduce postharvest rots.

Rinse fruit in clean water and dry with a soft cloth. Spread the gourds out on several layers of newspaper in a warm, dry place, such as an attic, for final drying. This should take 3 to 4 weeks.

Dried gourds may be marketed in their natural state or treated with a protective, shiny coating. Gourds may be waxed with a paste-type wax and buffed with a soft cloth; or shellac may be applied by spraying, brushing, or dipping to give them a hard, glossy finish.