Growing pumpkins: planting, fertilising & harvesting
Pumpkins are currently very popular to grow in the garden but also to use in the kitchen. With these tips your pumpkin harvest will be a guaranteed triumph.
The cultivation of pumpkins (Cucurbita) at home is becoming more and more popular in Europe. Especially in autumn the gorgeous vegetables can be bought in all colours, shapes and sizes. The pumpkin originally comes from America and is one of the most varied vegetables of all. In addition to their large fruits, the pumpkin plants are also appreciated for their striking yellow flowers and tasty pumpkin seeds. What is more, in the milder latitudes the planting of pumpkins can be very fruitful if the right measures are taken.
Despite the exotic origin of the vegetable, pumpkin cultivation in Europe is generally successful and high yields can be expected. In order for everything to run optimally, a few tips, which are explained below, should be followed.
The ideal location
The pumpkin is a plant that requires specific location conditions to develop well. Depending on the pumpkin variety, the pumpkin plant spreads 1.5 to 2 m² across the bed. Many varieties additionally climb up and twine during growth, such as the popular Hokkaido pumpkin (Cucurbita maxima). A climbing aid can be helpful for smaller pumpkin varieties. When planting, for example, a place close to the garden fence is suitable so that the pumpkin plant can climb up. Larger pumpkins should stay on the ground because of their weight.
Pumpkins are warmth-loving plants. The location for growing the pumpkin plant should therefore be sunny and sheltered from the wind. It is vital that the soil, on which the pumpkins are planted, warms up early. Light to medium soils such as sandy loam with a good water retention capacity and high humus content are therefore the best option. Acidic soils do not offer good conditions for growth; the pH value should be at least 6. When choosing the location, it is particularly important to observe the crop rotation: pumpkin should never be planted directly after other cucurbit or gourd family plants (Cucurbitaceae) in the same place. Gourd plants include courgettes, cucumbers and even melons in addition to pumpkins. Potatoes, legumes (Fabaceae) and cabbages, on the other hand, are great as previous crops.
These tips should be followed when choosing a location:
- Allow plenty of space (1.5-2 m²) and an opportunity to climb as a vine
- Sunny and wind-protected location
- Light to medium soils (e.g. sandy loam/loamy sand)
- High humus content and water retention capacity
- Acidic soil is a no-no (pH value > 6)
- As previous crops, no gourd plants (Cucurbitaceae); potatoes, legumes or cabbage instead
If these instructions are followed, the pumpkin plant will grow effortlessly and bear a number of scrumptious fruit.
The variations of pumpkins are remarkable – in fact, more than 800 pumpkin species are known and are available in all the different shapes, colours and tastes. The species cultivated in Europe, however, are largely limited to three: the giant pumpkins (Curcurbita maxima), which include the popular Hokkaido pumpkin, the Curcurbita moschata varieties, which also include the varieties Butternut and Muscat de Provence, and the Cucurbita pepo, which include the subspecies summer squash. You will find a huge selection of pumpkins in our variety overview.
A small overview of the most popular varieties:
- Uchiki Kuri: Hokkaido type variety with small onion-shaped fruits; smooth, bright orange skin; the orange-red flesh tastes delicious and is reminiscent of chestnuts.
- Tiana: Variety of butternut pumpkin, pear-shaped and light yellow in colour; firm and tasty flesh; resistant to powdery mildew; definitely worth growing!
- Muscat de Provence: a particularly aromatic pumpkin; has flat, deeply ribbed fruits with light orange/brown skin; the firm flesh has a strong orange colour and is very tasty; the variety also stands out for its long shelf life.
- Vegetable Spaghetti: bears elongated oval fruits with pale orange colour and light flesh; an Italian variety.
- Atlantic Giant: a giant pumpkin variety; can produce record weights (the breeder Dill won several records with this variety, e.g. European record 2009 with approx. 650 kilos); the yellow flesh of the light orange fruits is very tasty; suitable for preserving.
Pumpkin plants are relatively uncomplicated. Nonetheless, they are still sensitive to low temperatures due to their warm origin. There are two methods for growing pumpkins:
Direct sowing: In direct sowing, the pumpkin seeds (or seeds of other plants) are not sown until mid-May, after the last frosts of the Ice Saints (11th to 15th of May) have passed. Otherwise, it can become dangerous for the small plants below 5°C. Temperatures from 14 °C are necessary for the process of germination. The perfect depth for sowing is 2-4 cm. The seeds should be sown at intervals of 0.5-1.5 m and 1.5 m between the rows.
Pre-culture: An alternative to direct sowing is pre-culture in a pot. With this method, the seeds can already be sown in April and the young plants are planted in the garden bed from mid-May on. When growing in pots, one seed per pot should be planted 2-4 cm deep. The ideal germination temperature is 20-24 °C. As soon as the first one or two leaves (not the cotyledons) have formed and the frosts have passed, the plants are planted into the garden bed at the same distance as with the direct sowing method.
So, which of these two approaches is better? This depends on the location. In cooler areas the pre-cultivation in the pot is definitely worth it! In addition, you can expect an earlier harvest with this method. It is also worth covering the young pumpkin plants with fleece at the beginning of the season to protect them from late frosts. Protect plants with fleece before the flowers form so that pollination can take place unobstructed.
Caring for pumpkin plants
All in all, the care of pumpkins is not very time-consuming. Here are some useful tips with regard to pumpkin care:
Watering pumpkins properly
It is essential that the pumpkin plants are watered regularly. This is particularly important when fruit is formed, otherwise the harvest will be smaller. When watering, always water directly on the ground and not over the leaves – otherwise, there is a risk of rot. This can also occur with fruits that lie directly on the ground. Use a base (for example a board or an overturned pot) to lift the fruits from the ground.
Pumpkins require a lot of nutrients; therefore, regular fertilisation is advisable. Before sowing or planting the young plants, the soil should be prepared with compost. During the growing period it is recommended to fertilise once a week with nitrogen-rich fertiliser directly through the water supply.
The pumpkin plant grows quickly and its leaves are very large, so weeds don’t have it easy. But before the sweeping plants cover the soil completely, the young plants still have to compete with weeds. Therefore, weeds should be removed regularly, especially at the beginning, so that the plant has enough light, nutrients and water to grow.
Cutting back pumpkin plants and scarification
A popular method in the care of pumpkin plants is the removal of new shoots. The following applies to pumpkin cultivation: the more fruits grow, the smaller they become. It can therefore be worthwhile not to let all of the fruits grow, so that the rest get enough energy and nutrients. It is recommended to cut off the unnecessary side shoots for the first time in June. Shoots with 3 to 5 leaves above the second leaf are shortened. In July the pruning can be repeated again, only above the fifth leaf. After all the female flowers have been pollinated (this can be recognized by the fruit set), the male flowers should be removed. This also gives the plant more energy for fruit formation.
Tips for taking care of the pumpkin plant:
- Water regularly
- Do not wet the plant’s leaves and fruit when watering in order to avoid rot
- Before planting, work compost into the soil
- Fertilisation during the growth phase once a week with nitrogen-rich fertiliser (directly with the irrigation water)
- Regular weed removal (especially for young plants)
- Prune any unnecessary side shoots away
Pumpkin diseases and pests
Usually the weather has the greatest influence on the yield of the pumpkin. Heavy damage can be inflicted by hail, for example. Additionally, diseases and pests can make it difficult to grow pumpkins in your garden. A particularly unpopular guest in the bed is the slug, which likes to feast on the pumpkin plants as well as other vegetables. Especially if the spring is rainy and wet, slugs can become a huge hindrance. Collecting the small animals helps, but unfortunately the sneaky slugs mostly come out at night to feed. However, spreading coffee grounds between the plants can help protect the pumpkins, because the slugs avoid it.
Another danger for pumpkin plants comes from fungal infections. One problem can be powdery mildew, which can be recognized by a floury-white coating on the surface of the leaves. Infection with the Didymella bryoniae fungus can also occur at very hot temperatures. The fungus causes what is known as stalk burns, which manifest themselves in brown leaf spots, necrosis and rubbery stalks.
Tips to prevent fungal infections:
- Avoid damaging the plant at all costs
- Do not wet the leaves during watering
- Do not overdose the plant with nitrogen fertiliser
- Do not let the vegetation grow too dense
There is no one hundred per cent protection for the pests and diseases mentioned. In the case of fungal infestation, affected plants can be sprayed with a mixture of sodium bicarbonate, vegetable oil and curd soap. At an advanced stage, especially in stalk burning, the plant should be completely removed from the bed to prevent further spread of the disease. If these instructions are followed, the risk can be reduced and a good pumpkin harvest can still follow.
Harvesting and storing pumpkins
When summer is coming to an end, it is time for the harvest of pumpkins. This allows the healthy vegetables to be used in time for Halloween and the cold season.
Harvesting pumpkins properly
Depending on the variety, the pumpkins start ripening in mid-August at the earliest. However, most varieties are harvested between September and October. Harvesting before the first night frosts is recommended. These characteristics determine if the pumpkin is ready for harvest:
- Intense colour (easy to recognise, especially with orange-red varieties such as the Hokkaido)
- Wooded and dry stalk
- Leaves dry and die off
- Scratching the shell with the fingernail leaves no mark
- Hollow sound when knocking the fruit (does not apply to all varieties!)
The absolute best time to harvest is when the weather is dry. In this case, the pumpkins can dry outdoors for 2 to 3 days. To harvest the pumpkin, the fruit is separated from the stalk with a sharp knife.
Tip: Some of the stalk should remain attached to the pumpkin! This makes it harder for pathogens to penetrate the fruit and the pumpkin will last longer. On the whole, it is important to be very careful when harvesting the pumpkin, as damage to the fruit can lead to rot.
In general, the pumpkins you grow yourself can be in storage for a relatively long time providing that they are stored correctly. After harvesting, pumpkins should first ripen for about 3 weeks at 20 °C in a light and dry place. It is important that the pumpkin lies on a dry surface such as wood or cardboard and is turned regularly. Post-ripening improves the pumpkin taste and increases the germination capacity of the pumpkin seeds, which can be reused next year.
Pumpkins can then be stored for up to 6 months, depending on the pumpkin type and the way they are stored. A dry and dark place is perfect. The temperature should be between 12 and 15 °C. Lower temperatures can lead to rot, higher temperatures can have a negative effect on the taste. If these instructions are followed, you can enjoy the pumpkin throughout the cold winter months.