Pumpkin cultivation in the garden
Pumpkins are dramatic and adventurous, and the perfect garden project for the whole family!
Larger pumpkins are often used for decoration and adventure games. Especially for Halloween, which is celebrated on the 31st of October, pumpkins decorate many gardens. The Halloween tradition originates from a Celtic harvest festival, but according to popular belief, it is also a night when witches, ghosts, and the dark powers of the night are let loose. Lanterns made from pumpkins or root vegetables originate from an Irish legend about Jack, a drunkard, who is not allowed to enter heaven nor hell, and is doomed to walk the earth forever, because he did not believe in God and tricked the devil several times. He got a spark of hell's fire and found a rood vegetable to eat. He placed the fire in the chewed rood vegetable, creating a lantern, a jack-o’-lantern, and the legend has it that he still walks the earth with the lantern in his hand, searching for his final resting place.
Pumpkin cultivation is not nearly as dramatic, but more of a niche in garden cultivation. Squash is cultivated more often, but isn't that the same thing? Popularly speaking, a pumpkin is the same as a bigger squash. The name squash is an Indian word for something that can be eaten raw. The Indians call the thin-skinned, watery fruits 'summer squash' and the thick-skinned, heavy, and firm ones 'winter squash'. Because of the thinner skin, squash only lasts for a short amount of time, while pumpkins, with their thicker skin can last for several months. So maybe, what really separates a squash from a pumpkin, is its durability.
How to succeed with pumpkins
Pumpkins take some time to ripen. It is therefore important to sow the seeds in the middle of May, in a greenhouse or a place with a lot of light. People who participate in competitions with their pumpkins begin already in April. You can sow them in a pot and plant them out when they have 3-4 leaves, and when there is no risk of frost at night. That is often the case from the second weekend of June.
The plants don't like the wind or cold, so it can be necessary to protect them when planting out. You can, for example, use a grow tunnel, insect net, or something else that provides shelter and warmth. You can take off the protection when the weather is warm. It is important for the plants to grow as big as possible before they set fruit. This way, you will be able to harvest more. This also means that the soil has to be full of nutrients, as pumpkins need a lot of nutrients to develop properly. Some good compost will do the trick. People who grow pumpkins for competitions use organic fertilizer or horse manure to get the pumpkins as big as possible.
Place the seeds, about 10-12cm deep, tip down, into a pot with soil, and cover it with 1-2cm of sand. The sand helps to retain moisture. Cover the pot with plastic. The seeds will sprout after approx. 3-4 days. Take off the plastic and let them grow even more. They should have about 2-4 leaves before planting them out in soil filled with nutrients. This will typically take about four weeks after they have been sowed in the pot. You can sow them directly outside, but in that case, it takes a grow tunnel or a fibre net to get a good yield.
Harvest with stem
The pumpkin is ready to harvest, when the skin is hard and not earlier than that; otherwise, it cannot be stored and will instead rot quickly. Do not harvest too soon, but also not too late, which means before there is frost. Harvest the pumpkin with a little piece of stem and let it dry up. The stem will close any wounds that otherwise would remain on the pumpkin. It is important that there are no mushrooms close by, or your pumpkin will rot in the storage.
Don’t wash the pumpkin, but instead dry it with a cloth
When the pumpkins have been harvested, dry them off with a cloth and place them in a warm spot (25°C) for 10 days. During this time, remember to check regularly if the stalk is drying as it should, as mould often starts there. After drying, the pumpkin should be placed in a dry spot, but now at approx. 15 °C and never below 10 °C. It is a good idea to check on them once in a while to see if they are still durable. When one pumpkin starts to turn bad, the others will quickly follow.
The four recommended types are all from the Cucurbita genus: Cucurbita pepo, Cucurbita maxima, Cucurbita ficifolia, and Cucurbita moschata.
The traditional varieties are 'vegetable marrow,' 'busk,' and 'white bush.' They are commonly used for preservation. The white or yellow UFO-looking pumpkins, 'scallopini,' 'pattison,' and 'patty-pan', all have a thin skin and should therefore not be stored but eaten quickly.
'Spaghetti squash' is a cross between a summer and winter pumpkin. It should only be eaten when fully ripe, but because it has a hard skin, it can be stored longer than the other squash.
‘Pumpkin’ is the name for most pumpkins that are hard, round, a little grooved, and have a strong orange colour. They are typically the ones used for making pumpkin lanterns and the flesh is suitable for baking. However, it is not necessarily the most delicious variety.
How to break the record
To grow a giant pumpkin, you need a little luck and the right kind of seeds. You will also need a large greenhouse or a plastic tent around the pumpkin and 50kg of horse manure, which should be worked into the soil. On cold days and nights, wrap the pumpkin with a blanket to protect it. You might need baby powder to prevent your record-breaking pumpkin from cracking, and of course, lots of water. The seeds should be from the “Atlantic Giant” variety, although “Big Max” and “St. Martin F1” are good options as well. Even if you buy these seeds from a nursery, there is no guarantee that they have the right genes. The pumpkin will probably reach about 100 kg - if you are lucky even more. Never try, never know. You can also organise your own little competition with the kids or neighbours.
Cucumber and pumpkin roots
Pumpkin roots are strong compared to the roots of cucumbers. It is therefore not uncommon to combine a pumpkin root with a cucumber stem, without a root. In the video below, I will show you how.
Please note that the video is in Danish, but it is possible to choose English subtitles in the settings.
- Open the video on YouTube by clicking on the YouTube-icon in the right corner.
- Click on settings.
- Click on ‘Subtitles/CC’ and then ‘Auto-translate’ to choose your preferred language.
Om Lars Lund
Danish horticulturist and journalist
Lars Lund has for many years engaged in the garden and greenhouse. Lars has published many books about greenhouses, and he has participated in many Danish horticultural TV shows. He is a walking garden encyclopaedia, and he has answers for most basic cultivation questions – also the more ambitious ones.
- Current blog posts
- Three tips for the greenhouse
- For the plants to grow it takes fertilizer but which one?
- Sterile soil is not good for the plants
- Greenhouse plants also get sick
- Hens in the garden
- Provide shade for your plants
- The philosophical gardener’s theory of perennials
- Create good living conditions for animals and insects in the garden
- The golf courses great secret
- What you need to be aware of when growing in plastic