Tag Archives: light

OS7 Light and Sprouts

My seeds have sprouted. My sprouts are getting bigger. Perhaps yours are too. Here is Part 3 about growing the pumpkin vines with ideas about things you can study about them.

It’s time to start showing off our pumpkin plants. I will start a page of photo galleries of pumpkin plants. To get your own gallery so you can show everyone how well your pumpkins are doing, email me pictures of your pumpkin plant as it grows.

Project 1

Part 3

Growing Your Pumpkins


This is the hardest part of growing pumpkins for me. Maybe it is for you too. It only takes a few days to a week for the sprouts to appear but the time seems so long. One day there is that hook pushing soil aside or cotyledons open and pumpkin plants are growing.

The next step is keeping those plants growing and healthy.

Getting Started

Step 1: Only two miniature or sugar pie pumpkin plants can grow in one hill. Only one larger pumpkin plant can grow in a hill. More than two seeds should germinate so some have to go. Sometimes you can tell a sprout is very small or doesn’t grow very well. Pull these sprouts out. When they get their first true leaves, pull the smallest one. Do this again when the fourth true leaves appear until only three miniature or pie plants are left or two bigger pumpkin plants. Let the one grow to half a meter long, dig it out carefully and use it for Investigation 11. If the sun is very hot on your pumpkin plants almost all day, put up a shade to protect the plants from sunburn and dying. You can tell the sun is too hot if the edges of the cotyledons or leaves get dry and brown or they fade to light green.

Note: I hate to pull out a nice sturdy sprout and toss it away. It’s trying so hard to grow well. But it can’t stay where it is or none of the plants will do well later on. One solution is to transplant it someplace else. Pumpkins grow well with corn.

Step 2: While the plants are small, water them directly during the day. Once the plants start vining, water the vines by filling the moat and letting it soak in. While the vines are small, they may not need water every day unless it is hot. If the leaves wilt in the afternoon, you are not watering enough. Try not to get water on the leaves. Water your plants after the dew is gone but by early in the afternoon so the leaves get dry before sunset.

Getting Bigger

Step 3: Pumpkin vines grow extra or adventitious roots at every leaf node. The vines also grow in any direction. Before the roots grow, carefully move the vines to grow across your garden space. It’s best to do this while the vines are small and move them in the afternoon when the vines are softer. If the vine needs to be moved very far, do a little each day so you don’t break or bend the vine.

Step 4: The extra roots give you another way to feed the vines extra nutrients. This is very important for Halloween and giant pumpkins. For these vines, dig a little hole under the leaf node, put extra manure in it and cover it with dirt. Put dirt over the vines (not the leaves) to help protect them from borers and squash bugs. The dirt helps the adventitious roots grow faster.

Step 5: Especially for giant pumpkins, you may need to trim the vines and side vines when they get really long.

Step 6: Check your vines every day for insect pests and diseases. Pick off squash bugs and their eggs. Spray for cucumber beetles and flea beetles.

Keeping Records

Measure your plants for several days to find out how fast they grow. Write down how the plants change as they grow. Look at your plants at different times of the day and in different weather and write down comparisons. Describe how a leaf changes as it gets bigger then gets old.


When and where do your plants make adventitious roots? These are extra roots from the stems.

Giant pumpkin growers put dirt over the stems so the plants make more adventitious roots. What is the advantage of doing this?

When does your main vine put out a branch?

Does a branch vine grow faster than the main vine? Do you have to measure the entire vine to find this out?

Investigation 7

Plants need light to make food. A new sprout needs to start making its own food before it runs out of the food stored in the seed. How bright does this light need to be? What happens to a sprout if the light isn’t bright enough? Let’s find out.


Question: How does light affect a sprout?

materials needed


Long grow light

5 Styrofoam cups

10 seeds

Potting soil


Metric ruler

Plastic wrap

Books or blocks of wood to make steps for the cups


Step 1: Open your science journal and write the date. Put down Investigation 7. Copy Table 1 into your journal.

Step 2: Number the cups 1 to 5 and fill them with potting soil. The soil should be 1.5cm below the top after it is firmed down.

Step 3: Add water to each cup so the soil is damp but not soggy.

Step 3: Measure 2.5cm from the end of the pencil and make a mark. Use the pencil to make two holes 2.5cm deep in each cup.

planting the seeds

Each pumpkin seed is planted at the same depth in the same type of cup and potting soil.

Step 4: Put a seed in each hole. All the seeds should be planted the same way. Add potting soil to fill each hole. Cover the cups with plastic wrap.

Step 5: Build steps under the grow light so the top of each cup is 5cm higher than the next one. The grow light should be over the tops of all the cups and only 2.5cm away from the top cup.

Step 6: Turn the grow light on for 12 hours every day. Check for sprouts every day. When sprouts appear, take the plastic wrap off the cup. Don’t let the soil dry out.

Step 7: Describe, draw and measure the length of the stems in centimeters of all the sprouts every day until the first true leaves appear. Write the measurement in Table 1.


sprouts on steps

As the pumpkin sprouts get farther from the light, they grow taller trying to get to it.


Table 1: Length of sprouts

Table 1

Table 2: Describe the sprouts

 Table 2


Why do you make all the holes for the seeds the same depth?

Think back to other Investigations and explain why 2.5cm is a good depth to plant pumpkin seeds.

Why should all the seeds be planted the same way?

Is it important to have the light turned on for the first two or three days? Explain why you think this.

Does it matter how close to the light a sprout is? Explain why you think this.


sprouts lined up

A grow light isn’t really bright enough for a pumpkin sprout even when it is very close. But a sprout does its best to get close.

What happens to sprouts farther away from the light?

Think back to other Investigations you have done. Why is it important for the new sprout to have a short stem?

OS5 What Seeds Need to Grow

Different kinds of seeds end up on or in the ground in different ways. Pumpkin seeds are inside a pumpkin. Lots of animals eat pumpkins and the seeds. The seeds may just fall on the ground and be forgotten by the animal. Or the pumpkin may not get eaten but just rot and the seeds fall to the ground. However a seed gets to the ground, once there it wants to grow. How does a seed know it’s time to grow? Let’s find out about some things that might affect when and how a seed grows.


Question: Do light, water and temperature matter to a pumpkin seed and sprout?


3-Styrofoam cups filled with dry potting soil (Let the soil sit out in a tray to dry, stirring it every day until it is very dry.)

3-Styrofoam cups filled with potting soil

24-Pumpkin seeds


Plastic wrap


Metric ruler

A dark closet or box, a refrigerator [ask first], a warm, light counter


project set up

Each cup must be labeled so it is put in the right place. When the cups are compared later, the labels tell which cup is which.


Step 1: Open your Science Journal, write “Investigation 5” and the date. Draw Tables 1 and 2 in your journal.

Step 2: Label the cups DW, DY, LW, LY, CW, CY [D dark, L light, C cold; Y dry, W wet].

Step 3: Add water to all the cups with a W label so the dirt is damp but not muddy.

Step 4: Push two seeds 2cm deep in each cup, cover them and firm the dirt. Remember the best way from Investigation 4.

Step 5: Lay two seeds on top of the dirt in each cup.

Step 6: Cover the cups with plastic wrap.

Step 7: Put the two cups with a D label in a warm, dark closet or under a box.

Step 8: Put the two cups with an L label in a warm light place.

Step 9: Put the two cups with a C label in the refrigerator.

Step 10: Check the seeds everyday until the first seeds start to germinate. Take the plastic wrap off.

Step 11: Check and measure the sprouts everyday for seven days. Measure only the length of the stem. Try to do the ones in the closet quickly and use a flashlight with the door closed so they stay in the dark as much as possible. If the cups are under a box, wait until the room is dark and use a flashlight. Don’t shine the flashlight on the sprouts.

Note: Some of the seeds may not sprout. Start counting the seven days when the first seeds germinate.


Write down how long each sprout is in the table and what it looks like in your notes.


pumpkin sprouts

Only a couple of cups had pumpkin seeds germinate. Can you tell which one was in the light? Why are the tips of the cotyledons dark green when the rest is yellow green?


Are the seeds pushed into the dirt in the light or in the dark? Why do you think so?

Is this the same as putting the seeds in a dark closet? Why do you think so?

Why are some seeds pushed into the dirt and others left on top?

Does it matter if the seeds are in the light or dark to germinate? Why do you think so?

Does it matter if the sprouts are in the light or dark to grow? Why do you think so?

Does it matter if the seeds are wet or dry to germinate? Why do you think so?

Does it matter if the seeds are wet or dry to grow? Why do you think so?

Do you think how wet a seed is would matter? Can you think of a way to test your opinion? When you have, try it and find out if it matters how wet a seed is.

Does it matter if the seeds are warm or cold to germinate? Why do you think so?

Does it matter if the seeds are warm or cold to grow? Why do you think so?

Do you think these results would be true for all seeds? Why do you think so?

Which two cups do you think these are? Why do you think so?

Why do you think the tips of some cotyledons in the cup on the right are green when the rest is yellow?

[The dark green seedlings were in the light. The yellow green seedlings were under a box. The tips of the cotyledons poked out under the edge of the box.]