Growing Butternut Pumpkin

Latest update 27th August 2017.

Butternut Pumpkin. (Squash)
  • We love butternut pumpkin, its easy to grow, and is delicious in soups, roasted and even steamed with other veggies.
  • Grown organically its rich in vitamins, micro-nutrients and dietary fibre.
  • In an urban environment, where its sometimes hard to attract enough bees for pollination, you can hand pollinate them.  They carry both male and female flowers, but its best to grow 2 plants to increase the chance of both male and female flowers maturing at the same time.
  • They occupy a lot of space and I have been having problems finding the right spot for them.  This year I plan to try them in one of my small 900mm x 900mm x 600mm high Ecobeds .
  • Pumpkins will store for a few months, but are best used soon after harvest.   
  • Binomial Name:                                        Cucurbita Moschata.
  • Family:                                                    Cucrbitaceae.
  • Variety:                                                    Waltham.
  • Crop rotation group:                                  Legumes.
  • Garden bed type:                                      Small Ecobed.
  • Recommended soil pH:                             5.5 - 7.5.
  • Minimum sun per day:                              6 hours.
  • Plant spacing:                                          450mm
  • Weeks to harvest:                                    15 - 20 weeks.
  • Good companions:                                   Sweetcorn, citrus and sunflower.
  • Climate:                                                   Warm temperate.
  • Geography:                                              Southern hemisphere.
  • This food is low in saturated fat, and very low in cholesterol and sodium.
  • It is also a good source of protein, vitamin A, vitamin K, thiamin, niacin, phosphorus and copper, and a very good source of dietary fibre, vitamin C, riboflavin, vitamin B6, folate, magnesium, potassium and manganese.
  • More from nutrition

Growing Conditions: 
  • They grow best in warm sunny conditions.
  • They are frost tender.
  • For best results they need well structured, rich, moist organic soil.
Soil Preparation. 
  • Clear a space for pumpkins in August and add a 60mm layer of thermal compost.  Cover with 50mm of fresh straw mulch.
  • Leave the bed for 4 weeks to build up worm and microbial activity.
Growing Instructions.
  • In August, sow 2 pairs of pumpkin seeds in jiffy pots, soak them thoroughly in dilute seaweed extract and bury them up to there rim in an EcoPropagator.
  • Once the seeds germinate and become established snip off the weakest seedling in each pair
  • Transplant the two remaining vines in their jiffy pots into the end row of an Ecobed.
  • Support the vines on trellis as they grow.  This maximises their "sprawl" space and allows space for other plants in the growing area of the bed.
  • Control growth by snipping unwanted leaders and side shoots.  Aim to grow 4 or 5 mature pumpkins per plant.
  • Apply a foliar spray of aerated compost tea every 4 weeks when all the other edible plants are sprayed. 
  • Pumpkins produce both male and female flowers on the same plant.  They are dependent on bees to pollinate them, and will not set fruit if bees are not regular visitors to your garden.  Herbs and other plants flowering at the same time as your pumpkin and grown nearby will encourage bees to visit and pollinate your crop.
  • In warm climates you should grow Pumpkin as early as possible in the season because pollination is affected by high temperatures, and the balance of male to female flowers swings towards all male flowers when temperatures rise above 30 deg C.
  • To compensate for poor pollination by bees, you can hand pollinate your Pumpkin using the same method used for cucumbers see video.  Pollen is taken from the male flower using a small paintbrush and deposited on the stamen of the female flower. 
Harvesting and storage.
  • Harvest Pumpkins as they start to die back.  Their stalks should be dry when removing them from the vine with a short piece left on the pumpkin.  This helps protect it from disease in storage.
  • You can store the Pumpkin for months in this state in a cool dry place like your shed provided there is plenty of air circulating.
Organic Pest Control.
  • Slugs and snails.
    • Pumpkins should be protected against slugs and snails using self adhesive copper tape bonded around the base of your Ecobin.
    • If these molluscs get into your Ecobin as eggs laid in your compost, kill them with organically acceptable iron based snail pellets as soon as you discover them.  You should only need to use a small number of pellets.
  • Greenhouse whitefly.
    • Aerated compost tea strengthens the plants foliage against whitefly damage.  
    • Control any infestations by spray your crop thoroughly with organic horticultural oil (Eco-oil in Australia).
    • Spray again in a few days to ensure second generation whitefly do not survive.
  • Powdery mildew.  
    • A monthly foliar spray of aerated compost tea inhibits the establishment of powdery mildew on your plants.
    • A solution of 1 part cows milk to 9 parts water makes a reasonably effective alternative organic deterrent against powdery mildew.  However, it needs to be applied early before the fungi gets well established, and frequently to keep the mildew in check.
    • As a last resort use Eco-oil to remove the mildew.
  • Caterpillars.
    • Do not use exclusion netting on the Pumpkin.  Exclusion netting is usually the first defence against caterpillars, but the pumpkin depends on bees and other insects for pollination. 
    • Use commercially available, environmentally friendly, Bacillus thuringiensis sprayed onto the plants leaves to combat any infestation of caterpillars. 
  • General:
    • Regular applications of aerated compost tea boost the natural defences of Pumpkins by colonising the leaf surfaces with beneficial microbes.  They defend the plant against airborne pests and diseases.
    • Similarly, proper soil preparation including regular applications of home made compost boosts the plant's defences against plant pathogens.
    • Drape heavy duty shadecloth over your pumpkins in hot and windy weather (over 35deg C).