One of the things that I want to grow over the summer is some pumpkins as I enjoy eating them, especially in soup. Pumpkins, and squash, are annual trailing plants that are often very vigorous. The origin of pumpkins is the Americas, which seems to be the origin of many of my favourite plant foods! It has been estimated that they have been cultivated for between five ten thousand years. The Latin name for pumpkins is Cucurbita maxima, where the fruit are large and have hard skin at maturity, allowing them to keep well. Ideal temperatures are between 20-27 degrees Celsius, with low humidity.

Propagation

In Sydney, I can see my pumpkin seeds in-situ into the soil, provided the soil is above thirteen degrees. From what I have read, the seeds need soaking overnight and can be sown 2.5 cm deep into the soil (at least 60cm apart), when there is no danger of frost. Where I am in Sydney, I have never seen any sign of frost, so when the temperatures do start rising from next month (the start of spring), I can get going with sowing seeds. Pumpkins are rather hungry, so it is advised to dig in some well-rotted manure before sowing my seed, but I don’t have access to any so I’ll have to provide plenty of fertiliser as they are growing.

Growing

Pumpkins need a sunny position in a nutrient rich soil with plenty of moisture. If you can add plenty of well-rotted compost, that will be of great benefit. Placing a layer of straw as mulch over the soil is also beneficial as it suppresses weeds, keeps water in the soil and helps prevent the possibility of rotting pumpkins as they mature.

To ensure pollination, hand pollination is recommended- the female flowers have a swelling at the back of the flower while the males just have a stalk.

The plants need a large amount of water, especially once they start flowering. Ensure that they are never waterlogged. Provide liquid fertiliser once every two weeks.

When trailing varieties reach 60 cm long, pinch out the tips to encourage branching. They can be encouraged to grow over a trellis or some other support, which can save a bit of space if that is an issue for you (and can work well too).

If you want big pumpkins, limit the number of fruit to two or three per plant.

Harvesting

For pumpkins, harvest should be in late summer or autumn. They are mature when foliage dies and skin hardens and cracks. The pumpkins need to be left outside for fourteen days often the stem is cut from the plant. This enables the cold to improve the sugar content while also improving flavour, while also sealing the stem to prevent rot and hardening the skin. They can be stored for a maximum of six months over ten degrees.

Pest and disease problems

If there is sign of withering in fruit, the plant is not getting enough water.

Cucumber mosaic virus can cause yellowing and puckering of leaves with fruit rotting-remove the plant and dispose of in the general waste bin to prevent infection of future crops. Control aphids too-these little sap-sucking irritants can spread this virus!

Powdery mildew can be a problem, more in dry weather. I did try growing pumpkins last summer. I went on holiday for a week and it didn’t rain at home the whole week. My plants were fine before I went and when I got back, I had an extremely bad powdery mildew problem. I wasn’t happy as the plants didn’t do well after that! I will be trying again this year, hopefully with more success.

Companion planting

Companion planting is where several plants are planted together to the benefit of each different species of plant. Pumpkins are often planted with sweetcorn and legumes like peas or beans. The sweetcorn provides support for the legumes, the legumes provide nitrogen in the soil and pumpkins provide the ground cover for weed suppression and keeping more moisture in the soil.

Container growing

Provided you can get hold of moderately vigorous trailing or bush varieties, pumpkins can be grown in pots. It often says on seed packets if this is the case.

You do need to be aware that the plants will need more water and you will have to ensure fertilising occurs frequently as there is limited area for the plant to find what it needs within the pot growing media. Don’t let it dry out!

Again they can grow up stakes- tip prune once they reach the top of these and tie gently with twine.