Prizewinning pumpkins

8 Nov 2021

Cucurbita maxima, Cucurbita moschata, Cucurbita pepo, Cucurbita mixta

Pumpkins appear out of the compost in spring and take over a summer backyard without asking. But that’s ok. Although they’re a sprawling mess of a plant, we all know pumpkins as generous givers of versatile tasty food that keeps for months and grows without any help. Did you know that not only are the pumpkins edible, skin, seeds and all (just put the whole thing in the oven to roast and cut it up after – it’s so much easier!), but so are the flowers and the leaves? When they get out of control you can eat the prunings! Not only that but in this climate pumpkins can be perennials.

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Most pumpkins will do well enough here. Though varieties that don’t mind our heat and humidity and are less likely to succumb to funguses are a better bet.

The unanimous number one go-to pumpkin for growing here is the Jap or Kent (C. moschata). Why it has two names I do not know. This variety copes outstandingly well with our heat and humidity, it’s a vigorous plant and generous with pumpkins. Sounds too good to be true? Kinda. The jury is split on it’s taste. Some people find the flavour wonderful and it’s even their favourite. Others (like myself) find it watery and tasteless, or at best acceptable. Certainly the flavour seems to be helped by making sure it isn’t picked early but left to 100% fully mature first. Note that the skin is thin and they don’t keep as long as some other varieties. 14 – 16 or 20 – 25 weeks from sowing to harvest, depending on who you ask. 2kg fruit.

The next recommendation is the well known Butternut (C. moschata) pumpkin. Not as robust or fruitful a plant as the Jap, but the flavour is universally appreciated. 15 – 18 weeks from sowing to harvest. 1 – 1.5 kg fruit.

Also, Queensland Blue pumpkins (C. maxima) were consistently mentioned as growing well here. They are a rather large, hard skinned and so long-keeping fruit. The plant is robust and generous with pumpkins and originated in Queensland so does well in warm climates. 14 – 16 weeks from sowing to harvest. 3 – 4.5 kg fruit.

Gramma pumpkins (C. moschata) aren’t well known but those that are familiar with them are keen on their suitability to this climate. They are said to make the best pumpkin pies. The skin is very thin and they don’t store long at all. You have to cook up a storm of mash, soups, pies and scones which is what they are excellent for. 13 – 15 weeks from sowing to harvest. Medium sized long fruit to 60cm.

Two other varieties that are worth looking out for to grow in this area are Pimply Squash (C. moschata, 13 – 15 weeks from sowing to harvest, small fruit) and Spaghetti Squash (C. pepo, 12 – 16 weeks from sowing to harvest, up to 1.8kg fruit). Both grow abundantly and easily. The pimply squash is said to be delicious baked and spaghetti squash is…interesting; useful as vegetable spaghetti without much flavour of its own.

In more general pumpkin news, kabocha is more a type of smaller pumpkin developed in Japan than a single variety. Most but not all kabocha are interspecies F1 hybrids (C. maxima x C. moschata) – that’s a whole nother article. Briefly, this isn’t a bad thing, but the seeds saved from them won’t reliably grow pumpkins like the parent plant. The locally available potkins are hybrid kabocha types. The Jap / Kent is an open pollinated kabocha type that will grow as expected year after year.

For flavour, the old French varieties are outstanding. If you haven’t had the pleasure, you may not want to go back to the Jap / Kent afterwards. Their flesh is dry, firm and much more fully flavoured in comparison. Roasting makes these incredible. How do you recognise these varieties? The names are a good clue: Musquee de Provence (C. moschata), Rouge vif D’Etampes (C. maxima), Galeux D’eysines (C. maxima) – the more warts the sweeter it is.

There are four main species families of what we call pumpkin in Australia. They will cross with each other both within and across species. Different pumpkin varieties are recommended to be separated by 400m to avoid crossing. In a backyard, insect netting or pegging flowers shut to avoid uncontrolled pollination might be more practical.

Cucurbita maxima
There’s a lot of big pumpkins in this group, and the open pollinated kabocha types.
Queensland Blue, Jarrahdale, Atlantic Giant (the one used for the heaviest pumpkin competitions), Ironbark, Red Kuri, Blue Kuri, Buttercup, Rouge vif D’Etampes, Galeux D’Eysines.

Cucurbita moschata
This family group generally tolerates warmer wetter conditions than the others. You’ll see that most of the pumpkins that we know grow really well in this area are in this family. They don’t like really hot and dry. If in doubt, pick something from this species.
Jap / Kent, Butternut, Grammas, Pimply Squash, Musquee de Provence, Tromboncino (a zucchini substitute)

Cucurbita pepo
This is the zucchini family.
Zucchini, Button Squash, Crookneck Squash, Spaghetti Squash, Stygian Hulless, Small Sugar Pumpkin (and other acorn type pumpkins).

Cucurbita mixta
The cushaw squashes. There don’t seem to be any well known varieties of this family in Australia.

To encourage the best from your pumpkin friend you will need an area approximately 6m x 6m. Pumpkins tend to use up a lot of space and go wandering wherever they feel like it. They can be persuaded up a fence or trellis which saves space and makes mowing around them a lot easier. Yes, pumpkin stems and vines are strong enough to hold them up in the air. Note that female flowers tend to form on lateral branches not vertical.

You need to be able to get plenty of water to the roots at ground level. Watering the leaves causes fungus issues, especially in our already humid summers. Pumpkins like plenty of water (there’s a lot of fruit to fill up). Not enough water will give you small dry flavourless pumpkins. Those record breaking sized pumpkins will drink 1000L a day! Keep the soil moist, not wet. And make sure it’s well drained. Their extensive root system doesn’t like to sit in water.

Pumpkins also like plenty of food to create their large fruit.
Lots of compost, well rotted animal manures, some worm castings. Go for broke! Preferably weeks before planting out, even months ahead of time. They will need phosphorus at their root zone, and other minor minerals like boron, manganese and magnesium and especially zinc. Crusher dust has these. They also need plenty of potassium (potash / burn piles). Their pH preference is 6.0 and 6.5, although they will tolerate both slightly acid and slightly alkaline soils.

The root system of pumpkin is far more extensive than you may realise. Back in 1927 a research project was done by John Weaver and William Brunder which found that, “Vines of ‘Small Sugar’ pumpkin were about 16 feet (4.8m) long at maturity and the top 12 inches (30cm) of soil were filled with roots. The taproot of mature pumpkins grew 6 feet (1.8m) deep and had 10 or more lateral branches that extensively branched outward for 5 to 17 feet (1.5 – 5m) or more. Many of these lateral roots were 2 to 4 feet (0.6 – 1.2m) long and all complexly and minutely rebranched, forming a “wonderfully efficient root complex”. The second and third feet (0.6 – 0.9m) of soil were also thoroughly filled with roots, with the fourth foot of soil containing many vertically descending roots.”

Competitive pumpkin growers fully prepare their soil in a 5m x 5m area, though professional growers of regular eating pumpkins concentrate their main soil prep around the main planting, about 60 x 60cm. Those competitive types also bury the vines at each leaf node as it will develop a root. All the extra roots help grow pumpkins. They also trim off the growing tip at 5m, just past a root node, for the main stem and 3m for others to encourage fruit not leaves, and bury the cut end to grow roots.

Perennial is possible. If you are able to locate your pumpkin patch in a frost free place, with deep rich soil you may be able to keep your pumpkin plant for 5+ years. It will die back over winter and reshoot from the extensive root system in spring. Under a deciduous tree with dappled summer shading is a situation that works.

A bit of shade doesn’t go astray. While full sun is generally recommended, plenty of growers arrange some light shade for their pumpkins and sometimes the plant as well over high summer. Pumpkin fruit will get sunburnt, and need a bit of shade or turning to avoid this. The plants can have their growing tips zapped by UV and will wilt in the heat. Temperatures of 20°C to 35°C are ideal for pumpkins. Above this, especially with low humidity, will slow down pumpkin-making and pumpkins will be aborted under stress such as excessive heat.

Mulch mulch mulch. One of the biggest issues with growing pumpkins is weed pressure. Keeping the grass down while the vines are rambling means you can find the pumpkins, and they don’t have to compete with grass which is also hungry by nature. Unless you’re ok to clip around them with scissors (you know who you are!!), heavily mulch the pumpkin patch so you aren’t tempted to take a whippersnipper to the whole overgrown mess.

If you are thinking of trying the Native American three sisters method of corn, beans and squash (pumpkin), as far as I can tell this was done using the smaller pumpkins – the cushaws and acorn types. Our available equivalents would be kabocha types and butternut and spaghetti squash.

Pumpkin is a warm season plant. Frost is the death of it. They need a long warm growing season of 4 – 6 months to make their big fruit. You can start planting the seeds from August, though the best soil temperature for germination is above 16°C. It can take up to 14 days for germination at this temperature. At a soil temperature of 20°C, seeds emerge within a week, and at 25°C, within four days. The plants won’t do much until the soil and weather warms up, about November, but it’s good to get them going before this. Sowing after November is probably getting too late, depending when your first front arrives. Count backwards to see if you have enough time.

Sow the seeds pointy end down. When they have their first true leaf, and well before they start becoming pot-bound, transplant them out to the pumpkin patch with about a metre between plants. They object to their roots being disturbed so be gentle. Or, sow a few seeds direct and while they are still young plants, snip off the weakest ones at ground level leaving one strong plant per sowing. They will appreciate protection from slugs and wind for their first 6 – 8 weeks.

The first flowers will be male ones. Female flowers will begin to appear 8 – 10 weeks after the seed germinates. Female flowers have small pumpkin (about the size of a 20 cent piece) at their base. High temperature, low humidity and long day-length encourages male flowers. Female flowers are encouraged by the opposite conditions. If you want to have more growing time, hand pollinate. If you don’t have bees around you will absolutely need to do this. Go out early in the morning. Find a newly opened male flower. Pick the flower and pick off the outside petals. Find a female flower. Open it gently and paint the female stigma with the male pollen-covered stamen.

After 12 weeks the plant will have a main stem with side vines coming off at approximately 90 degrees. These are hungry plants who will definitely like to be fed once or twice a week. A little and often otherwise the fruit can split if you suddenly overdo it. For best results, make sure the plant has plenty of available nitrogen and phosphorus while it’s growing leaves and vines. Don’t overdo the nitrogen as this can prevent the fruit from setting. Around or soon after pollination, switch to making sure the plant has enough potassium.

Beware of downy mildew and powdery mildew in our humidity. Ensuring good amounts of calcium, silica (sand, diatomaceous earth), and sulphur will help the plant. Potassium silicate liquid foliar spray will help too.

Keep an eye on those almost- ready pumpkins late in the season. You may find rats like pumpkins too. Commercial growers set up traps amongst the vines. Also if the weather gets wet the fruit can start to rot on their underside, so turn them to avoid this.

And finally they are ready!
Once the stalk becomes dry and cracked or corky they are fully ripe. You also shouldn’t be able to easily poke your nail through the pumpkin skin and if you do break the skin this way the sound should be crisp. Pumpkins picked too young do not store as well and have noticeably less flavour. Leave about 6cm of stalk on the fruit as this increases their storage time. And while they are in storage, check them regularly for any rodent nibbles or rotting – the rot spreads from pumpkin to pumpkin. Eating ripeness is seed saving ready. Just scoop out the seeds before cooking.

Big thanks to:
Camilla of Autarky Farm, Paul of Barefoot Fruit & Veg, Tom of The Mandarin Bend, Ian of The Gourmet Garden School

Also to: Michele Morozumi, Tim Hill, Jeff Alcott, Nick Radford, Pete Bufo, John Vernon, Carole & Phil Helman, Sue Lennox

Supported by Bellingen Shire Council via the Bellingen Shire Disaster Recovery and Resilience Grant Program Funding

Notes

1. Brown J. Community effort grows giant pumpkin [Internet]. Good Fruit & Vegetables. 2019 [cited 2021 Oct 29]. Available from: http://www.goodfruitandvegetables.com.au/story/5949166/community-effort-grows-giant-pumpkin/

2. Brown J. Pumpkin a giant slayer in spite of season [Internet]. The Land. 2021 [cited 2021 Oct 29]. Available from: http://www.theland.com.au/story/7084139/pumpkin-a-giant-slayer-in-spite-of-season/

3. Fanton M& J. The Seed Savers Handbook. The Seed Savers’ Network; 2008.

4. Jamie. Soil Prep Time & Time for Amendments in the Pumpkin Patch [Internet]. [cited 2021 Oct 29]. Available from: http://www.giantpumpkinman.com/2019/03/soil-prep-time-time-for-amendments-in.html

5. Morgan WC, Rural Industries Research and Development Corporation (Australia). Kabocha and Japanese pumpkin in Australia: a report for the Rural Industries Research and Development Corporation. Barton, A.C.T.: Rural Industries and Research Development Corp.; 2003. Available from: https://www.agrifutures.com.au/wp-content/uploads/publications/02-167.pdf

6. Napier – Pumpkin production.pdf [Internet]. [cited 2021 Oct 28]. Available from: https://www.dpi.nsw.gov.au/__data/assets/pdf_file/0004/311485/Pumpkin-production.pdf

7. Growing Queensland Blue Pumpkins (Winter Squash) [Internet]. The Greening of Gavin. 2013 [cited 2021 Oct 29]. Available from: https://www.greeningofgavin.com/2013/12/growing-queensland-blue-pumpkins-winter.html

8. Get set to grow your plumpest pumpkin! [Internet]. [cited 2021 Oct 29]. Available from: https://www.rockhamptonregion.qld.gov.au/AboutCouncil/News-and-announcements/Latest-News/Get-set-to-grow-your-plumpest-pumpkin

9. Growing Pumpkins Hints and Tips. Royal Agricultural Society of NSW; [cited 2021 Oct 29]. Available from: https://www.rasnsw.com.au/globalassets/document-library/rasnsw/competitions/pumpkin-challenge/growing-pumpkins-fact-sheet.pdf

10. Organic Vegetable Seeds Online – Pumpkin [Internet]. Green Harvest. [cited 2021 Nov 8]. Available from: https://greenharvest.com.au/SeedOrganic/VegetableSeeds/Pumpkin.html

11. Pumpkin MythBusters: How Big is a Pumpkin Root System? [Internet]. Giant Pumpkin Growing Tips. [cited 2021 Nov 5]. Available from: http://www.giantpumpkinman.com/2019/04/pumpkin-mythbusters-how-big-is-pumpkin.html

13. Pumpkin World – Slow Food Hunter Valley [Internet]. [cited 2021 Nov 8]. Available from: https://www.slowfoodhuntervalley.com.au/pumpkin-world/

14. SEED VEGETABLES P – S Pumpkin [Internet]. The Lost Seed. [cited 2021 Nov 8]. Available from: https://www.thelostseed.com.auhttps://www.thelostseed.com.au/pumpkin/