Pumpkins are a fun backyard crop for home gardeners. Kids find great joy in watching the massive vines grow and then form orange orbs, ready for carving or pie baking. However, sometimes things don’t go quite right in the pumpkin patch. It’s disappointing when a pumpkin crop is ripe months before Halloween’s arrival. It’s also disappointing when homegrown pumpkins don’t ripen in time for the Thanksgiving feast. Knowing when to plant pumpkins so they’re ready to harvest at the perfect time is a major key to enjoying this vine crop. Let’s dive into all the factors that influence when to plant pumpkins. With this information, you’ll be able to determine the best pumpkin planting time for your region.
There are many factors that help determine the best time to plant pumpkins. I’m going to discuss most of these factors in greater depth throughout this article, but this initial bulleted list gives you an idea of how many considerations are involved in the proper timing of pumpkin planting.
- Soil temperature
- Air temperature
- Soil moisture level
- The average first and last frost dates in your region
- The variety of pumpkin you are growing
- Days to maturity of each variety
- Whether you’re growing from seed or transplant
How to plant pumpkin seeds
There are two routes you can take when it comes to the seeds—you can either remove them from the inside of a fresh pumpkin or buy ready-to-plant seeds at your local garden store. If you’re going with the first option, there’s some prepping you’ll need to do before you plant them in the ground.
First, you’ll need to clean off the pulp. Place the seeds in a colander and rinse them with cold water. “Once you’ve rinsed all the seeds, separate and select the biggest seeds,” Watson says. “They have a better chance to grow and flower. Space them out on a paper towel, so they can air-dry.”
If you’re not ready to plant them just yet, you can store the seeds by putting them in an envelope and placing them in the back of your refrigerator.
For store-bought seeds, Watson suggests choosing between these three varieties: Autumn Gold if you’re looking to grow pumpkins you can carve; Dill’s Atlantic Giant if you want to grow giant pumpkins upwards to 200 pounds; and Casper if you like all-white versions.
When it’s time to put the seeds in the ground, be sure to do it properly.
“Pumpkins grow best when you plant the seeds directly into the ground about one inch deep,” Watson says.
Where to plant pumpkin seeds
“Pick a planting site with full sun to light shade,” Watson says. “Keep in mind that the soil should be able to drain because pumpkins prefer soil that is not too soggy.”
The pumpkins will need some room to grow, so you’ll need to clear a big spot in your backyard.
“Due to large vines, it is best to plant your pumpkin seeds five feet apart,” Watson says. “If you are growing a smaller variety of pumpkins, the spacing changes—instead, space them three feet apart.”
Check the pH of your soil (which you can do with a kit)—it should read between a 6 and 6.8. Make sure the area is clear of any pests, insects, and weeds: “You can use weed block two weeks ahead of planting, which will allow the weeds to die naturally,” Watson suggests. Another option?
When to plant pumpkins
The best time to plant pumpkin seeds is by late May to early July, so you can enjoy them in the fall.
How to grow pumpkins
Ideal pH: 6.0-6.8. These big plants need lots of food. Choose a sunny spot with fertile, well-draining soil. Dig in a generous quantity of finished compost and/or composted manure. Dig in 1 cup of complete organic fertilizer under each plant. All pumpkins grow male flowers first, then the female flowers are produced. The female flowers have tiny fruits at the base of the petals and require pollination by bees, mostly. Incomplete pollination is common at the beginning of the season, and results in small fruits that are misshapen at the flower end. Discard these damaged fruits before they rot.
For the largest pumpkins, feed weekly throughout the growing season with fish or kelp based fertilizer. Keep the huge plants well watered, particularly in hot weather. Always water the soil, and avoid any form of overhead watering other than rain. Fruit will grow larger if you keep only one fruit per vine. As the fruit develops, try to gently encourage it to grow at a 90° angle to the vine itself. The largest pumpkin varieties will grow on their sides.
How to harvest
Like other winter squash, pumpkins are mature when they have coloured up well and their stems are crisp. For the best sugar content, cut the stem about 4cm (2″) or so from the body of the fruit. If the weather is dry, allow the pumpkins to cure in the field for 10 days, or in a warm room for 4-5 days. Bring pumpkins in under cover before rain.
Diseases & Pests
Powdery Mildew: An airborne fungal disease that causes white spots on the leaves at the end of the season. Several home-sprays are said to be somewhat effective. Spray any of the following at 7-10 day intervals. 1tsp baking soda and 1 quart of water with a squirt of dish soap, or 1 part milk to 9 parts of water. You can add a little kelp based fertilizer to the mix. Resistant varieties get the mildew just a few days later than the other varieties.