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How to Plant and Grow Pumpkins
- Krista Green
- 6 hours ago
- 5 min read
Learning how to grow pumpkins from seed in Zone 3 (you can find your gardening zone here) isn't always easy. At least, it wasn't for me! For years, I struggled to grow pumpkins successfully. Season after season, I faced disappointment, but each failure taught me something new.
After plenty of trial and error, I finally discovered what works well for growing pumpkins in zone 3 gardens. Over the past few years, I've been able to grow healthy, beautiful pumpkins consistently—even with a short growing season of only 60 to 80 frost-free days. Many of you have asked what I changed, so today I'm sharing the tips and techniques that made all the difference!
Disclosure: This website may include affiliate links from which I earn from qualifying purchases.Best Pumpkin Varieties for Short Growing Seasons
There are 2 main varieties of pumpkins: pie pumpkins and carving pumpkins (grown for size). Pie pumpkins tend to be much smaller and, in my experience, easier to grow in cool gardening climates. Last year, I grew Connecticut Field Pumpkins (for carving) from Heritage Harvest Seeds and had good success, as well as Small Sugar Pumpkins from Heritage Harvest Seeds. West Coast Seeds also has a nice Small Sugar Pumpkin and a good Jack-of-all-Trades carving pumpkin.
When to Plant Pumpkin Seeds Indoors
Year after year, I have experimented with planting pumpkin seeds indoors versus direct seeding. For the past 5 years, I have done both, and each year the pumpkins I started indoors have surpassed the ones I direct seeded in size. I live in the foothills of Alberta and often get a light last frost in mid-June. If you live somewhere even just a little bit warmer, go ahead and try experimenting both ways yourself to see which ones do better. Because pumpkin plants often go into a bit of shock when they are transplanted, direct sowing is the way to go if your growing climate permits and your growing season is long enough.
It is key to not plant pumpkin seeds indoors too soon. The best time to transplant pumpkin seedlings is when they have their third true leaf. If pumpkin plants are any larger, they are more prone to go into severe transplant shock. Plant pumpkin seeds indoors between April 21 and 28 to transplant outdoors on June 1.
How to Plant Pumpkin Seeds Indoors
As a rule of thumb, plant seeds as deep as they are from end to end. Plant pumpkin seeds 1 inch deep. Packages often recommend planting 2 or 3 seeds and thinning them to the strongest seedling. Partly because pumpkin seeds can be quite expensive, and partly because it is hard to kill a healthy seedling, I only plant one seed per pot.
Because pumpkin plants grow very quickly and because they do not like to be transplanted, plant seeds into at least a 2.5 inch diameter pot. I have used both these pots from West Coast Seeds as well as these peat pots from Amazon. When transplanting I remove the bottom of the peat pot and leave the sides intact.
Make sure you harden-off your pumpkin plant seedings before transplanting them outdoors.
How to Plant Pumpkin Seeds Outdoors
Plant pumpkin seeds outdoors 1 or 2 seeds per hole (if more than 1 germinate, thin to the strongest seedling), 1 inch deep and at least 2.5 feet apart. Vines often spread 4+ feet, so be sure to plant them in an area where there is plenty of space for the vines to spread. If you are growing in a northern climate, cover seeds with some sort of dome to keep the soil/seedlings warm. This can be a jar placed upside-down, the top of a gallon milk jug, the top of a large water jug, a poly dome, a cold frame or anything else of the sort. These plastic cloches from Amazon work well.
Keep seedlings covered until night temperatures are consistently greater than 10 degrees Celsius (50F).
Transplanting Pumpkin Seedlings
As mentioned previously, pumpkin plants are prone to transplant shock. It is not unusual to look out the day after transplanting pumpkins to see many of them dead and wilted. For greatest success transplanting, follow these steps:
Carefully harden off pumpkin plants prior to transplanting
Transplant when night temperatures are expected to stay above 10C (50F) or keep covered with a cloche until night temperatures are warm
Water seedlings well the day before transplanting
Plant into warm, moist soil
Try not to disturb the roots at all when transplanting
Water well with room temperature water after transplanting
It is especially important to make sure pumpkin plants do not dry out during that first week after transplanting
Avoid watering pumpkin plants with cold water until they are well established
Avoid getting leaves of pumpkin plants wet, as they are prone to powdery mildew
My Biggest Secret to Sucessfully Growing Pumpkins...
I have mentioned a cloche a few times already. Seriously, using a cloche made all the difference. Get as large of one as possible. Dollarama sometimes carries cloches in the spring. The secret is... leave the cloche over the pumpkin plant until the leaves have almost filled up the inside of the cloche. This goes for all gardeners in cool, northern climates.
Before trying this, I had thought leaving a cloche on would "cook" the pumpkin plant during warm spring days. But I found that leaving it on was not the case. I left my cloche on during days with temperatures up to 24°C (75°F), and the pumpkin seedlings underneath thrived. Keeping them warm seemed to prevent them from going into shock, and I ended up with much quicker growth. It wasn't until the very end of June that I removed my pumpkin cloches.
Another way to keep soil warm is to use black plastic mulch. Pumpkin plants will grow quicker when the soil is kept warm.
The Best Soil for Planting and Growing Pumpkins
Pumpkin plants are heavy feeders. If you wish to grow large pumpkins it is ESPECIALLY important to provide plants with soil high in nitrogen. This can be done by adding compost or adding an amendment such as alfalfa pellets (yes, like the ones you feed rabbits) or a urea fertilizer.
A Note on Squash Cross Pollination
Many people become concerned that squash planted near each other have cross-pollinated. This is, in fact, not possible if you are using pure seeds. Cross-pollination does happen when you save seeds from squash. If the squash was grown near other squash plants, the saved seeds may produce a mix of whatever it cross-pollinated with. This is partly why squash seeds can be expensive to purchase.
Planting and Growing Pumpkins in Pots
Growing pumpkins in containers is difficult because they need large pots or grow bags, but it can be done with the pie pumpkins. Select at least a 5 gallon container, but it is even better if you can find a 10 gallon one for each pumpkin.
A benefit of growing pumpkins in pots is that you can direct sow them in the pots indoors and move the entire pot outdoors once the weather warms up and all risk of frost has passed. You will still need to spend at least a week hardening off the pumpkin plants before leaving them outdoors overnight.
