Compost Cups Science Project

Toilet paper rolls seem to be piling up around here, so we turned them into a compost cup science project. I decided it would be a good idea to reuse them as seed starters instead of throwing them away. Plus, toilet paper rolls are biodegradable, so there is no leftover pot once the seed grows and is ready to be planted in the ground!

Make our free Seed Starting Log as part of this compost cups science project. Check out our Observing Seeds and click on the free seed starting log.

Compost Cups Science Project

Cost: $5

Materials

empty toilet paper rolls
soil
masking tape
permanent marker

Instructions

Cut a toilet paper roll in half.
On one end of a toilet paper roll half, fold two edges towards each other.
Tape the two edges from step 2 together, then fold the other two edges towards each other.
Tape the two edges from Step 2 together, then fold the other two edges towards each other.
Fill your little seed pot with dirt, add the seed, then cover it with just a little dirt. Water and set aside in a sunny spot!
Label the pots so you know what type of seeds were planted. Write directly on the pot.

Other Compost Cups and Recycled Seed Starters Ideas

Compost cups science experiment idea

Egg shells, lemon and orange halves, cardboard egg cartons, paper towel rolls, and newspaper are other materials you can use to make compost cups. In fact, make an experiment out of this compost cups science project by making several cups out of egg shells, several out of toilet paper rolls, several out of newspaper, and several out of orange halve.

Then, place each the same seeds in each compost cup and place the cups in the same place, water them the same amount, and water them at the same interval.

Below is a list of materials that can be used to make compose cups or recycled seed starting cups.

Egg cartons – We have used the 12 and 18 egg paper cartons and the 36 egg plastic cartons. You can see those here. You can also use cardboard egg cartons.
Plastic water bottles – These can be used to not only start the seeds but water them too. We share this below.
Plastic berry containers – What I love about these are the drain holes and lids that help create a little greenhouse or sorts. Be sure to use the deeper ones so the roots have more room.
Newspaper – We don’t use this anymore because, honestly, we read our news online. But here is an idea for these.
Plastic pots from last year – I do buy some of my flowers, and especially new herbs I want to grow, so we save their containers and reuse for starting seeds.
Paper towel tubes – This is the same concept as using the toilet paper rolls, but I cut them in half.
Spinach or lettuce containers – These are the big plastic box containers with the lid. I typically do not like purchasing produce in these big plastic containers, as they are so much plastic! So, when we do have to purchase these, I save them and use for seed starting recycling projects.
Paper and plastic cups
Egg shells – Eggshells are primarily composed of calcium carbonate, which slowly breaks down in the soil and provides a steady source of calcium to seedlings. Calcium is essential for strong cell walls and helps prevent disorders like blossom end rot in tomatoes and peppers.
Orange and/or lemon halves – Citrus rinds are biodegradable, so you can plant them directly into the soil along with the seedlings. As they decompose, they enrich the soil with organic matter.
Apple or pear containers from Costco – We used these in this activity.
Take out containers or fast food plastic containers
Other recycling containers like yogurt or sour cream containers
Plastic water bottles

There are a number of ways of starting seeds indoors (that is another detailed post on starting seeds) is not complicated and it doesn’t require any high-tech or specialized equipment. In fact, you probably have the main supplies you need at home right now. When I plant, I only want to spend money on seeds and maybe good potting soil if it’s too cold to dig topsoil.