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
Let’s tackle each of these topics and look at how they impact when to plant pumpkins.
When to plant pumpkins using the soil temperature
If you plant in cold soil, pumpkin seeds could rot or fail to germinate. The seeds of most pumpkin varieties germinate at soil temperatures between 65 and 85° F. Planting seeds too early in the growing season is a recipe for low germination rates and a poor crop. Wait until the soil temperature falls within that range before planting. An inexpensive soil thermometer is a big help in determining when to plant pumpkins. Even if you are planting transplants instead of seeds, I suggest waiting until that soil temperature target is reached. Otherwise, the transplants will languish rather than thrive.
Timing pumpkin planting by the air temperature
Another important factor in determining the best time to plant pumpkins is the air temperature. Though it’s not quite as critical as the soil temperature in determining germination rates and times, it does impact how quickly the seedlings take off. Cool air temperatures mean slower growth. Warmer temperatures translate to more rapid growth. However, you never want to plant pumpkin transplants on a hot, sunny day as it could lead to transplant shock.
Planting pumpkins according to soil moisture content
Wet spring soils often result in rotten pumpkin seeds, rather than happy seedlings. If you have a wet spring with a lot of rain and the soil is waterlogged, it’s always better to wait a little longer to plant pumpkins, even though the soil temperature may fall within the proper target range. This is particularly important in regions with heavy, poorly drained, clay-based soils.
Alternatively, when planting pumpkins, don’t plant the seeds or transplants into very dry soil either. If it’s been very dry in your garden and you’re ready to plant, water the garden thoroughly with a hose or sprinkler a few hours prior to planting. The soil should be moist down to a depth of at least three inches at planting time.
When to plant pumpkins using frost dates
Perhaps the most common way to determine the best time to plant pumpkins is to watch the calendar. Each region has an average last spring frost date. When this date passes, you are not likely to get any further spring frosts, though occasionally Mother Nature does pull a fast one on us. In my Pennsylvania garden, the last expected frost date is May 15th. In warmer climates, the last frost date may be sometime in April or even March. In colder climates, it could be late May or June. Reach out to fellow gardeners in your area or visit this website to determine the average last frost date in your growing zone.
Once you have that date in-hand, add two weeks to it. That’s the start of the best pumpkin planting time for your garden. That being said, in northern regions where the growing season is short, you’ll want to start with transplants instead of seeds. In these short-season climates, every week counts, and if you want your pumpkins to mature in time, transplants are the way to go. Another option is to choose a variety that matures in fewer days (more on this in the next section).
How variety impacts when to plant pumpkins
As I just mentioned, the variety of pumpkin you’re growing is also a factor in determining the best planting time. Though pumpkins would never be considered a fast-maturing crop, some varieties are ripe earlier than others, often by several weeks. Pay attention to this when deciding which types of pumpkins to grow.
Another thing to consider is whether you’re growing pumpkins for eating or pumpkins for decorating. It’s far more critical that pumpkins intended for consumption are ripe at the proper time than those meant for decoration only. Some pumpkins have a very thick rind and they can sit ripe on the vine for weeks without rotting. Others have a thinner rind and they aren’t intended for storage. If you want a pumpkin that stores well, look for a variety that is noted to have a long shelf-life.
Days to maturity and its influence on planting time
For me, this is the #1 factor in deciding when to sow pumpkin seeds or plant transplants out into the garden. If you want your pumpkins to be ripe a few weeks before a particular date (Halloween, Thanksgiving, or a fall wedding for example) you need to look at the “days to maturity” of the variety prior to planting. Some pumpkins ripen in as little as 80 days, while others take as many as 110 days to go from seed to harvest. That’s a difference of a month! Count backwards from the day you want to harvest your pumpkins by the number of days to maturity and then add two more weeks to get the date you should plant your pumpkin seeds. If you’re growing from transplants, be sure to add in the amount of time the seeds were growing in their containers before being planted outdoors.
For example, if you want to harvest in early October and you’re growing a variety like ‘Spartan’ or ‘Mrs Wrinkles’ that takes 100 days to mature, planting day should be sometime during the first or second week of June. You always want to allow about two extra weeks of “wiggle room” so late-forming fruits can also ripen. Also, keep in mind that the speed of ripening will slow down once cold fall weather arrives. Pumpkins that form late in the season may not develop their full color before fall’s frost arrives.
When to plant pumpkins from seed sown in the garden
Growing pumpkins from seeds planted directly into the garden is often more successful than starting seeds indoors and planting transplants. There is no transplant shock and the plants are growing in their permanent home from day one, which is certainly less work for the gardener, too. Plant pumpkin seeds as early as two weeks after your last frost date. To determine how late you can plant pumpkin seeds, use the days to maturity count as described above.
When to plant pumpkins from seed indoors
If you live in a cold climate with a short growing season (less than 110 days or so), plant pumpkin seeds indoors under grow lights two weeks before your last expected spring frost. Then, move the transplants out into the garden two weeks after the danger of frost has passed (be sure to harden them off first – here’s how). These four weeks of indoor growing are often enough to get a jumpstart on the growing season and enable you to harvest ripe pumpkins before cold fall weather strikes.
When to plant pumpkins outdoors from purchased transplants
For gardeners not interested in sowing their own seeds indoors under grow lights or for those who prefer to grow from transplant instead of seed, pumpkin seedlings are sometimes found for sale at local nurseries and garden centers. In general, pumpkins don’t take kindly to growing in the tight quarters of a little pot, but if it’s your only option, give it a try. Just be sure to choose plants that have not yet come into flower with nice healthy roots.
As you can see, there are many factors that come into play in determining when to plant pumpkins in your garden. Thankfully, they are a forgiving crop and planting a few weeks too late or too early isn’t the end of the world, as long as you definitely wait for that frost date to pass before planting. Feel free to experiment with planting times and keep notes in a garden journal so you’ll remember what worked and what didn’t in subsequent years.
For more on growing great vine crops, please visit the following articles:
- Cucumber trellising ideas
- Harvesting winter squash
- Cucumber plant spacing
- Growing spaghetti squash
- Growing watermelon in containers
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