You just have to love pumpkins! They come in all sizes, with a host of interesting variations, from tiny gourd-like fellas all the way up to the massive giants. They go from a single, modest-sized seed to create a massive plant with a huge amount of biomass spread out over a significant area. They can be used for decorating on their own, or they can be carved. They can be eaten in different ways, but my preference is, of course, the classic pumpkin pie.
However, most importantly, in my opinion, they are the absolute undisputed hide-and-seek champions of the vegetable world, with a hint of world domination tendencies. Ok, well maybe they are co-champions with zucchini, but they are pretty epic at hiding.
Where it all began (for me)
I don’t really recall growing pumpkins as a kid, but it is possible that we did it. My first significant memory of growing pumpkins was when I was working as a summer student in the Vegetable Research Program at the University of Saskatchewan in the summer of 1998. We were testing many different vegetable crops that year, many of which were warm-season types. We grew dozens of different varieties of tomatoes, peppers, melons, winter and summer squash, and, of course, pumpkins. We laid down row after row of different types of plastic mulch, along with drip irrigation lines, to increase the rate of growth of the vegetables. We grew many of the plants from transplants started earlier in the greenhouse. In some cases, we also compared them to direct seeded plantings. We used row and field covers to augment the growing conditions around the plants. We did everything that we could to push those plants to the limit. It was a full summer, as in addition to the daily work of planting and tending to the needs of the different crops (mostly weeding and watering), I was carrying out a two-part research project for my undergraduate thesis. I spent a lot of time at the Horticulture Field Lab, with bonus evening work at the field lab with my wife and toddler son.
The reason the summer sticks out so distinctly in my memory (other than it was the first and only time my son willingly helped in a garden – he was 1.5) was that it was a beautiful growing season. It was hot, sunny, and the summer weather lasted close to a month longer than normal. Everything grew well, and we had a bountiful harvest.
To help me refresh my memory on some of the results of that year (and the principles and concepts that I’d only loosely cemented into my memory), I touched base with my friend, Jackie Bantle, who is a legendary vegetable grower (and who supervised my wayward efforts for those formative years).
What do pumpkins really need?
That summer, the pumpkins did really well, although, that isn’t necessarily unusual for them. They can produce a crop most years, given half a chance. They prefer fertile, well-drained soils, with lots of heat and sunlight, and a good amount of moisture to support them.
Warm soils (above 16°C) are preferred for pumpkins to germinate. If temperatures are below 10°C, they won’t grow, and if they are exposed to cold temperatures after they are out of the ground, they will die. This narrows the window significantly. Using technology to improve the air and soil temperatures will tip the balance back into their favour.
The plants were drip irrigated, so that we didn’t waste water on the vast open spaces (the between row spacing is anywhere between 3 and 8 feet). Pumpkins like to have about an inch of water or so per week, and must have water during flowering and fruit set, and then as the fruit develops and sizes up.
Seed versus Transplants
All pumpkins are going to be started from seed, whether you start them indoors to produce a transplant, or seed them directly into the soil in the field. That year, we tested whether growing pumpkins from seed made more sense than growing them from transplants. The answer was “it depends”.
If you have a good, warm growing season, you aren’t going to necessarily see a whole lot of difference between direct seeding and transplanting, because the direct seeded plants will have time to catch up. The nice thing about growing from seed is that the plant comes up and is entrenched in the outdoor environment from the get-go, and as a result doesn’t experience the same stresses that a transplant does (or doesn’t stress out the same way).
Growing pumpkins from transplants can be risky. If you grow them too big, such as beyond one or two true leaves, they can really take a beating when they arrive in the field. My experience with pumpkin transplants is that they often flop badly when they hit the field, as the heat and the wind can do a real number on them. Larger and older transplants will often go into shock, which can stall their growth and undermine much of the benefit that you gained with starting earlier.
If you are going to start from transplants (and that is likely a requirement in most places), make sure that they are young, so that they can bounce through the transition and remain productive and growing.
Supportive Technology
As I mentioned, we used floating field covers to help the pumpkins grow more quickly. We used to weigh them down and then pull them off occasionally to weed between the rows. Once the plants got large, there wasn’t much need to weed underneath them. I seem to remember having some plants in the bare ground, but pumpkins will benefit from using a plastic mulch, perhaps more than almost any other technology.
Pumpkins can be prone to bottom rots if they spend too much time sitting in a damp, wet spot, particularly if there are any soilborne pathogens present. Some growers use grassy cover crops to provide a bit of a protective bed for them to rest on.
Flowering and pollination
Pumpkins require insects to carry out pollination. Pumpkins (like other cucurbits) have both male and female flowers. Anything that you can do to encourage pollination (including introducing bee colonies) will increase your yield. The bigger the area that you have, the more pollinators you will need.
Pumpkin harvest is the ultimate game of darts…
To me, the challenge with growing pumpkins is that you are essentially shooting for a single, tiny harvest target. Sadly, that target just happens to be 4 or more months into the future. Worse, if you miss it, you are done. While you can sell pumpkins for a period of time before October 31st, you cannot sell pumpkins afterwards, generally. There are some limited markets for pie pumpkins, and certainly you can use pumpkins after Halloween, but for the most part, Halloween is the focus.
Post-harvest care
Pumpkins need to be at least physiologically mature when they are harvested. This way, once they are picked, you can ripen them (get them to colour up) if you have to. If they’ve had a bit of colour change already, they are definitely there.
It is usually recommended to give pumpkins a bit of time to heal any wounds and tighten up any tissues that might be vulnerable to attack. Holding pumpkins for up to three weeks at warm temperatures (24-30°C) can help them to heal any minor scuffs and scrapes. I’ve heard of people giving pumpkins a bit of a light wipe down with a dilute cleaner to get rid of any surface pathogens. You don’t have to wash them, but you can, if they don’t stay wet.
Whether or not you cure pumpkins, they can be held/stored in cool/warm (7-15°C) temperatures, in a protected, somewhat dry place. I think that they should be put on wooden pallets or up off the ground or floor.
Any pumpkins that have been exposed to frost, or that show any sort of decay or breakdown, should be tossed, so they don’t spread the disease that will develop on them.
Conclusions
Pumpkins are an interesting crop. You spend a lot of time focused on getting them started in the ground, and then have a tight harvest window. If you can beat the frost on either end of the season, you can do well.
In a smaller garden, you can plant a single plant in one area and then watch it attempt to take over the entire space. I might have to try one in my raised beds and just let it run around the yard. It’ll probably be adorable.