15 Tips for Growing Giant Pumpkins
Have you always wanted to grow epic pumpkins? Growing giant pumpkins takes a bit of extra planning and work. But under the right conditions, you can grow some epic-sized pumpkins. In this article, certified master gardener Laura Elsner walks you through 15 tips for growing epic-sized pumpkins in your garden.
Everyone should try growing a giant pumpkin at least once in their gardens. If you have the space, that is. These fall beasts are satisfying to watch grow from seed into a Goliath of epic proportions.
If giant pumpkins are on your agenda, we’re providing 15 tips to help you cultivate the most epic, gigantic pumpkins. Explore the possibilities of growing something on a scale you’ve never dreamed about before!
Not all varieties of pumpkins will grow large. If you want to grow giant pumpkins, you must choose a type capable of growing to epic sizes.
Miniature pumpkins, like ‘Sugar Pie,’ can only produce six to seven-inch pumpkins. While these are the most delicious for baking in pies, they won’t reach epic size.
Choose a seed like Big Max or Atlantic Giant for the most epic-sized pumpkins. Starting with the correct variety is the most important factor in your success.
Most giant pumpkins take 120 days to mature, so plan ahead. Pumpkins do best if their seeds are direct-sown after the danger of frost has passed.
If you’re like me and live in a cold climate, you can start them indoors. Wait to start them until it’s the right time to start them! This is a common mistake.
When the package says to sow your seeds indoors four weeks before the last frost, it does not mean eight weeks is better. Your pumpkin plants will be long and spindly and won’t transplant well. Stick with the four weeks.
I recommend using compostable cups that you can plant straight into the soil. They break down naturally over time, reducing root disturbance. A system like the Epic 4-Cell trays is also a great option for early, healthy root development that avoids the circling that often happens in some compostable containers. Pumpkins are sensitive to any root disturbance, so be gentle when transplanting them into the garden.
Give Them Space
I can’t help myself. When I plant vegetables, I plant things close and use every bit of space.
But if you want the epic-sized pumpkins at the end of the season, you have to be prepared to give them lots of space. I’m talking about 10 feet per pumpkin.
Initially, you’ll want to plant more plants in that vast space. But trust me, plant only one epic pumpkin per 10-foot area. These plants will be heavy feeders, and their vines may put down additional roots as needed to help fuel those gigantic yields.
Prepare The Soil
Pumpkins like light loamy soil that retains moisture but drains excess freely. They also prefer slightly acidic conditions.
If you start your pumpkin patch from scratch, prepare the bed with fresh loam. I like using a triple mix blend that has a mix of garden soil, compost, and peat. This ensures a perfect light, airy soil full of nutrients, is slightly acidic, and retains water evenly.
If you have a spot you’ve been growing pumpkins or squash, I suggest adding some fresh compost or organic matter to refresh the soil. Also, remember to rotate your crops so you aren’t always planting the same thing in the same place to prevent pests and diseases.
Use a Raised Bed
Using a raised bed is a great way to ensure you have the proper soil and that the soil is warm enough in the spring to get a good start on your pumpkin growth.
Since pumpkins need a lot of space to grow (up to 10′), I recommend a low-raised bed, maybe only a foot or so in height. This way, you can still amend the soil but aren’t buying copious amounts of soil to fill a large tub. Their vines may spill over the edges, as well!
Birdie’s metal raised garden bed can be adjusted into various dimensions. They work great for pumpkins if you keep the plants pruned.
Water Amount and Timing
Watering is essential when it comes to growing epic pumpkins. They require a lot of water to grow the mostly water-based fruit.
Too much water and the pumpkin can rot. Signs of overwatered pumpkins include yellowing leaves and rot on the pumpkins.
Ensure the soil is evenly moist but not soggy or wet. Having soil that drains well is critical. This will give you some leeway with the amount of water. The soil will absorb and drain if you tend to overwater.
The time of day you water is a crucial factor to consider as well. Pumpkins (and other squashes) are notoriously bad for getting powdery mildew. You are almost guaranteed to have it on some of your pumpkin leaves. This isn’t always a problem, but too much can stunt and destroy a pumpkin vine, ruining your chance to grow giant pumpkins. This is why I water in the morning.
If you water in the evening, the leaves will remain damp overnight. This is a breeding ground for mildew.
On the other hand, if you water in the heat of the day, much of the water will evaporate, and you won’t get maximum absorption. Watering in the early morning allows maximum water absorption, and the sun will be up and dry those leaves, minimizing the risk of developing powdery mildew on the foliage.
If you have the option, always opt for ground-level watering. A soaker hose snaked through your pumpkin patch is an excellent watering method. It will deliver water straight to the roots without getting the foliage wet.
Mulching your pumpkin patch will help your pumpkins grow in various ways.
First, it ensures your pumpkins have adequate water. Mulch can hold water. This will help keep your pumpkin patch moist but not soggy, even on the hottest of summer days.
Second, mulch will help keep the weeds down in your pumpkin patch. Keeping your pumpkin patch weed-free is vital for growing epic-sized pumpkins. Weeds will compete for light and nutrients, which you do not want. This can significantly impact the overall size of your mature pumpkin.
Lastly, mulch provides a clean and dry spot for your pumpkins to reside. Pumpkins left sitting directly on garden soil are more prone to rot and pests, whereas those on a mulch are often raised above the soil’s surface and are slightly more protected from soilborne problems.
There are a variety of mulches that can work in your pumpkin patch. Bark mulch, straw, coco coir, or hay will all mulch your pumpkin patch nicely. You can also use landscape fabric if desired. This will keep the weeds down and provide a dry spot for your pumpkin to grow on.
Pumpkins, like all squashes, have male and female flowers. The male needs to pollinate the female flower for a pumpkin to grow. You can leave this to bees and other pollinators.
But to be sure of pollination, I recommend taking nature into your own hands and hand-pollinating your pumpkins to ensure they grow. First, you have to distinguish between male and female flowers.
Male flowers have a straight stalk that blooms into a flower. The female flower has a swelling at the base of it, which, if pollinated, will turn into a pumpkin. To hand-pollinate:
- Use a soft bristle paint brush (such as one in an artist brush set) to brush the pollen from the male flower. Spend at least ten seconds brushing the paintbrush around the center of the male flower to collect as much of the yellow pollen as possible. You will see the yellow dust on the end of the paintbrush.
- Take it to a female flower and brush its stamen with the paintbrush. Again, do this for at least ten seconds to ensure successful pollination.
- You can also pluck off a male flower, pull the petals back to expose the inner stamen, and rub that onto the female flower. This method is great if you don’t have a paintbrush handy.
One of the most frequent squash questions I am asked is how to pollinate when your plant is only producing one gender of flowers. If you have a surplus of male flowers and no females, you can tie off the end of a male flower to hold it closed until a female flower appears. Zip ties or small elastic bands work great.
If you have excess female flowers, cover them in cheesecloth until they can be pollinated. This will ensure that your female pumpkin isn’t cross-pollinated.
Cross-pollination happens when pollinators jump from flower to flower between different squash varieties and create cross-breeds of squash. For epic pumpkins, you do not want other species cross-breeding.
Pick the Winner
If you want a truly epic pumpkin, you will want to select one pumpkin to reign supreme. Or, if you want a few, that’s ok too. But you don’t want a vine full of pumpkins if you want them large. Less is more for truly gigantic pumpkins!
Choose the biggest, strongest-looking pumpkin, and then remove the rest. You can grow a few if you’d prefer a few smaller ones over one gigantic one.
Once you have picked the winning pumpkins, snip off all the other flowers and pumpkins as they pop up. You want all the energy going into the pumpkins you chose.
Bury the Stems
A robust root system is critical for giant pumpkins. More roots mean more water and nutrient absorption.
Every leaf node, the point where the stem turns into a leaf, has the potential to grow into roots. This will not only help with nutrient and water absorption, but it will also provide stability to the plant.
Bury portions of the stems with soil so roots can develop and will grow strong and sturdy from the nodes. Don’t bury the entire vine, but only small parts where you’re relatively certain that it’ll set roots. This will help your plant become more vigorous overall.
Use the Right Fertilizer
Fertilizer is essential when it comes to growing giant pumpkins. Three numbers are labeled on fertilizers.
The first number is nitrogen. Nitrogen is essential for foliage growth. When you plant your pumpkin, using a higher nitrogen fertilizer will promote initial development.
Use caution with nitrogen fertilizers, as they can burn your plant. Never fertilize a dry plant. Water first, then apply fertilizer.
I like applying blood meal to my vegetables when I plant them. It is high in nitrogen (12-0-0) and keeps critters away, which is ideal for newly planted plants. Sprinkle it into the soil.
But later on, you want less nitrogen. Instead of vine development, once the plant’s already developed good vines, you’ll want to focus on more fruit growth.
The second number in NPK is phosphorus. Phosphorus plays a vital role in flower and fruit production. Once flowers appear, make sure you are fertilizing with a fertilizer that provides enough phosphorus.
The third number is potassium. This is the nutrient necessary for the plant’s overall health. Throughout the pumpkin plant’s life, ensure it gets enough potassium. However, be warned, more is not better. Too much potassium will cause your pumpkins to split and crack.
A 10-10-10 is just fine to get started. A 10-20-20 is excellent once the plant is flowering. Make sure to water the plant before fertilizing, and don’t over-fertilize. More is not better. Every two weeks is a good amount.
Use Shade Cloth
While pumpkins love full sun, too much sun, especially the hot afternoon sun, can impact your ability to grow giant pumpkins.
The hot sun can ripen your pumpkin prematurely before reaching its final epic size.
Shade cloth can come in a variety of forms. It can be an actual shade cloth placed directly over the pumpkin. It can be staked and placed above the pumpkin.
You can use sheets or tarps in place of the shade cloth. You can even use sun umbrellas to provide shade. Just aim to keep the hot afternoon sun off your pumpkin.
Pruning your pumpkin vine is essential to grow massive pumpkins. There are three types of growth on your pumpkins. They are called primary vines, secondary vines, and tertiary vines.
The primary vine is the main vine of your pumpkin. This is the one that will grow up to 10′ or more in length. Secondary vines shoot off of the primary vine laterally. Tertiary vines sprout off the secondary vines.
You need to prune your pumpkin vines for gigantic pumpkins because the more vines you have, the more energy is diverted away from pumpkin growth. But you also need lots of green growth to provide energy. It is a delicate balance.
Once your primary vine has grown about 10-15′ or has outgrown its space and is starting to wander and crowd other parts of your garden, snip the end off of it. This will prevent that vine from continuing to grow outward but will tell the plant to focus on the fruit already developing.
Allow some secondary vines to grow off the main vine. This gives the plant more stability and more leaves to provide energy. You may have pumpkins growing on the primary or secondary vines. You can prune off secondary vines if they are outgrowing their space the same as primary vines.
Prune off any tertiary vines. These vines sprout from secondary vines and will take energy away from the fruit growing on your primary and secondary vines.
Monitor for Pests and Diseases
You won’t be able to grow giant pumpkins if they are struggling with pests and diseases.
Powdery mildew is a disease that affects all squash plants, it seems. If you let it get out of control, your pumpkins will perish. To prevent powdery mildew, avoid getting the foliage wet if possible. Water using a soaker hose to water directly at the soil line. Or, if you are overhead watering, do it in the morning so the sun can quickly dry the leaves. Growing in a greenhouse with no overhead rain is excellent, too, if you have that option.
If you do have powdery mildew, prune off all the affected leaves. Then, spray the plant with a fungicide formulated for powdery mildew. Milk also works as an antifungal for plants. Use a 40/60 ratio of milk and water in a spray bottle and spray this onto your pumpkins’ leaves.
Monitor your pumpkins for signs of pests and manually remove them as you see them. Plant companions like nasturtiums, marigolds, radishes, and oregano can help deter pests. It’s also a good idea to rotate your crops as a means of prevention for pests.
Provide Support for Your Pumpkins
Finally, your epic pumpkins will need support. If you spend all your time and energy growing epic pumpkins only to find out the bottoms of them rotted, you will be devastated.
When your chosen pumpkin is still reasonably small, slide something underneath it (cardboard, plastic, fabric, a thick layer of straw, etc.). Ensure the amount is significant enough for your pumpkin to fit on when fully grown. Keeping it off the damp soil will help prevent the bottom from rotting.
Growing giant pumpkins is a labor of love. If you want the biggest, best pumpkins in your garden, follow these 15 tips, and you will be well on your way to epic squash!