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The Pumpkin Project

OSP1Pt2 Let’s Grow a Pumpkin

Project 1

Part 2

Let’s Grow a Pumpkin!

You know where your pumpkin plants will grow. You know what kind of pumpkin you will grow. You have purchased your seeds. Now let’s plant your pumpkin seeds.

When Do I Plant My Pumpkin Seeds?

Pumpkin plants will die if frost gets on them. So you must wait until after the last frost date for where you live. You can look this up.

If you can protect the plants from frost, you can plant earlier. There are lots of ways to help with a mild frost. Make a plastic tent over the plants. When the plants are very small, you can scatter some straw over them for the night.

Pumpkin plants like the weather warm but not really hot. They will not make pumpkins above 90°. So you must plant them early enough to start making pumpkins before your summer gets too hot. It takes sugar pie and Halloween sized pumpkins about six weeks to start making pumpkins.

Giant pumpkins take a lot longer so many people who grow giant pumpkins start their plants indoors. If you want to do this, think back to your Investigations to know the best way to start your seeds. Use 16oz cups or bigger. Don’t start your seeds more than four weeks before you can transplant them outside. Usually they are transplanted when the first or second true leaves appear. They must be transplanted before the fourth true leaves or the vines won’t grow as well. If you have enough room, you can test this.

You can start the other pumpkins indoors too but you don’t need to.

How Do I Plant My Pumpkin Seeds?

How you plant your pumpkin seeds depends on the kind and where you will plant them. Let’s begin with starting giant pumpkins indoors.

Giant pumpkins do take extra care. A good place to get instructions is at www.bigpumpkins.com or in the books by Doug Langston.

Starting Your Pumpkin Seeds Indoors

Step 1: It’s important to give pumpkin roots lots of room so use big Styrofoam cups 16oz or bigger. Only one seed will go in each cup so have enough cups for the number of plants you want plus a couple.

Step 2: It’s important to not make the dirt too wet in the cup so you need to make a hole in the bottom for extra water to drip out of. These cups have a little button on the bottom. You can cut this button out and have a good hole.

Step 3: Put a small rock over the hole inside the cup so the dirt won’t fall out. Then fill the cup with potting soil. Firm it down and add water so it is moist but not soggy.

Step 4: Make a hole 2.5cm deep in the soil and put in a seed. Cover the seed up. Set the cup aside in a warm place until it germinates. You can put plastic wrap over the top to keep the soil moist or check it every day and add water when needed.

Step 5: Light is very important for a sprout. If you use a grow light, it must be only 2.5cm over the sprout. If the days are warm, you can set the cup and sprout outside for the day. It can be in light shade outside. Even the shade is brighter than a grow light. The sun may be too bright for an indoor sprout. Be sure to bring it in at night.

Step 6: Transplant your sprout into your garden spot when it has two true leaves. Be sure you transplant it before it has four true leaves as it will have run out of room in the cup by then. If the sprout gets crowded in the cup, the plant will never grow as fast or as big as it should in your garden.

How To Transplant Your Pumpkin Sprout

Step 1: Prepare your planting hills the same way as in the directions for Planting Outside.

Step 2: Water your cup so the dirt is very wet. This makes it easier to get the sprout out of the cup.

Step 3: Make a hole in the top of the hill big enough for the cup to fit in. The sprout should not be planted deeper than it is in the cup.

Step 4: Slide the sprout and dirt out of the cup. Put it into the hole. Fill the hole with dirt and firm it against your sprout.

Step 5: Sprinkle water on the hill so the dirt settles around your sprout.

Growing Your Pumpkin In a Pot

Perhaps you don’t have a garden or other place outside. You can still grow a pumpkin. It must be a miniature pumpkin but there are several to choose from.

Step 1: Choose your pot. Even a miniature pumpkin plant needs room so the pot must be 16 inches or more across the top. Be sure it has a pan under it. You can use a big bag of garden soil in a box. Be sure you line the box with plastic then put the bag of soil in it.

Step 2: Decide where you will put your pot. Your pumpkin plant needs plenty of light so a south facing window or outside is the best. Once all the dirt and your pumpkin plant are in the pot, you won’t want to move it.

Step 3: Position your pot. Place rocks over the drainage holes in the bottom of the pot. Put three or four inches of gravel on these rocks. This helps water get into and out of your pot.

Step 4: Fill your pot with potting or garden soil. Add water to settle the dirt but don’t make it soggy.

Step 5: Make a small mound in the middle of the pot. Plant three or four seeds in the mound. Water them.

Starting Your Pumpkin Seeds Outdoors

Only giant pumpkin seeds really need to be started indoors. Even they can be planted outdoors. All other kinds of pumpkins can be started outside when spring arrives with warm weather.

Planting Your Pumpkins Outside

Step 1: Dig a hole one shovel length deep (only the metal part, not the handle), two shovel widths wide, and one meter long where you want your pumpkin vines to grow. Put a shovel full or two or three of compost in the hole. Put the dirt back on top of the compost to form a hill. Use the shovel to tamp the dirt down firmly. You need one hill to grow two miniature or sugar pie pumpkins, two hills two meters apart to grow two Halloween pumpkins and two hills three meters apart to grow two giant pumpkins.

Step 2: Make a moat or trench at least ten cm deep around the base of the hill to hold water.

Step 3: If you did not spread manure in the fall, spread composted manure over the garden area. I like it three or four inches deep. Use the tiller or a shovel to mix the manure into the dirt.

Step 4: Push 4 to 6 pumpkin seeds into each hill. Cover the seeds. Water the hill gently so you don’t wash the seeds out but get the dirt wet so the seeds are wet.

Step 5: Watch for your seeds to sprout.

Keeping Records

Write down when you plant your seeds. Write down when your sprouts appear. Every day write down what is happening to your pumpkin plants. How do your plants change as they grow? When do their first true leaves appear? When do your vines appear?


How do the cotyledons change as the pumpkin vines begin to grow? Compare this to what you saw in your Investigations. If this is different, why do you think it is?


The sun is very far away. Compare how sprouts grow in the sun to how they grew in Investigation 7. Is the sun brighter than a grow light?


What happens when the pumpkin roots find the manure? How can you tell? Why do you think this happens?