Pumpkins are grown on all continents, with Antarctica being the exception due to the harsh, cold climate. Pumpkins are frost sensitive and require frost-free growing periods of around 4 to 5 months.
High temperatures (above 35°C) and low humidity are not conducive to high yields. Temperatures of 20°C to 35°C are ideal for maximum production. Soil temperatures above 16°C are required for seeds to germinate and it can take up to 14 days for plants to emerge at this temperature. When the soil temperature rises to 20°C, seeds emerge within a week, and at 25°C, within four days of planting. Pumpkins require maximum temperatures greater than 22°C, to grow to maturity. In long term high temperatures poor fruit set will be prevalent. Once sown, it generally takes up to 24 weeks for the parent plants to mature and grow fruit that is ready to harvest.
One pumpkin vine can have several male flowers. The male flowers, which have no baby fruits behind their petals, can be picked to pollinate the female flowers, and the rest can go into the cooking pot.
The female flower of the pumpkin is not picked. The reason is, once the female flower is pollinated it becomes the pumpkin fruit. The female pumpkin flower can be identified via the small baby fruit that is located just behind the petals.
The picture below shows the bud of a female pumpkin flower which will eventually turn into a pumpin.
Using the male flower, find an opened female flower and brush the pollen laden anthers against the stigma of the female flower. In the process, one will notice some of the pollen being coated onto the stigma.
After a day, the female pumpkin flower will fade away but at that stage, it’s hard to tell whether it will turn into a fruit.
It is best to allow the fruit to mature on the vine and then harvest them when the vine has completely died off, leaving as much stalk on the fruit as possible. When choosing a pumpkin look for bright yellow-orange flesh which has a sweet, nutty aroma.
Some pumpkin varieties, such as the Jarrahdale or the Queensland Blue, will store on the vine for up to seven months over winter, whereas Butternuts store for a maximum of four months. However, storage duration becomes shorter during the warmer months as the pumpkin will ripen quicker.
Once harvested, the pumpkin should be stored as a whole in a cool, dark, well-ventilated place for up to two months. Once cut, wrap the pumpkin in plastic and store in a refrigerator for up to 7 days. All pumpkins and squashes grown for storage should be left to ripen in a bright place. Or you can simply cut them and leave them on the plot, protected from frost. This process helps the skin harden and improves the shelf life dramatically.