Can Watermelon Be Composted?

Nothing beats the summer heat like a plump, fresh, juicy, red watermelon. I spent many summer days in my youth breaking open watermelons and devouring the succulent flesh. After spitting out the seeds and wiping off my face, I often would toss the rinds into the compost pit at the bottom of my yard.

Little did I know that what I was doing was not the best thing for my compost pile. Even though, at the time, I thought the compost pile was some magical earth mouth that would devour everything we couldn’t, the science of composting has some very specific rules.

Was I following those rules? Can watermelon be composted?

Can I Put Watermelon Rind in My Compost?

Watermelon rinds can be put in your compost and will decompose with no issues. When adding watermelon to a compost pile, there are a few things you should do to help with the microbial balance. Here’s what you should include in your compost with your watermelon peels.

Watermelon has a lot of water in it, and this can lead to excess moisture in a compost pile. Excessive moisture can be a huge problem in compost piles leading to foul odors, death of aerobic bacteria, and other messy issues. Fortunately, there are a few things you can do to help your compost process watermelon rinds correctly.

What I like to do is add dry leaves and brown materials to offset the extra moisture. Following a ratio of 30:1 will give the compost the correct amount of carbon to counter the high nitrogen in watermelon. Paper or cardboard can also be added along with watermelon peels to improve compost balance.

A great thing about balancing the compost pile is it provides better environments for worms and other compost critters to do their work. The more alive a compost pile is, the faster that waste can become soil for your garden. This is also a good time to add bone and blood meal to help your plants grow even larger next season.

How Long Does it Take for a Watermelon to Decompose?

It can take from several weeks to several months for a watermelon rind to decompose. How long it takes for a watermelon to decompose can come down to a number of factors. By understanding and controlling these factors, we can help to break down rinds faster and achieve a more uniform compost material sooner.

4 Ways to Speed Up Composting

  • Chop Up the Materials – One of the easiest and most effective ways to speed up the entire composting process is to reduce the size of the organic materials going in.

For materials like watermelon peels, chopping them up is usually enough to speed up the process. Chopping creates smaller pieces that break down faster and gives more surface area for microbes and critters to interact with the waste.

  • Add the Correct Ratio of Carbon and Nitrogen-Rich Materials – Adding too much dry matter can cause your compost to sit inactively. Adding too much moisture may result in nasty smells and highly underutilized bacteria.

The key is finding the balance between materials that are composed mainly of nitrogen and carbon. 30 parts carbon to 1 part nitrogen is the common ratio for balanced compost.

  • Turn the Compost Every Few Days – If you have the time and energy, a few things will speed up the composting process, like turning the pile. When you turn a compost pile, new areas are exposed to oxygen and can set off a chain reaction.

This fresh air causes a massive bloom in bacteria and heat. The heat and increased microbes activate to jumpstart the next stage of decomposition. It is easiest to flip a pile using a shovel or pitchfork or a tumble-style lawn composter.

  • Add More Worms, Microbes, and Mycelium – A common reason it may take materials like watermelon rinds several months to break down is that there are few living organisms in your compost pile. Different organisms can be added to help your pile thrive.

Worms are extremely important and do a majority of the work in aerating and adding structure to your compost. Microbes are needed to feed the worms and initiate the various stages of warm and hot temperature decomposition. Mycelium can add a support network that increases the speed by which everything operates and is able to break down harder inorganic materials such as rocks and stones.

What Composts Like Watermelon?

Fruit Composting

There are lots of food scrapes that can be added to a compost pile on any given day. Having laid out the steps to take to properly compost watermelon rinds, it is natural to ask if there are other waste scraps that compost like watermelon. These materials may take the same amount of time to compost or require similar steps to prepare. Let’s take a look below!

MaterialTime to DecomposePrepared Like Watermelon
CantaloupeAbout 1-monthChopped
Honeydew MelonSeveral MonthsChopped
Apple CoresSeveral MonthsNot chopped
Banana Peels3 to 4 weeksChopped
PumpkinsSeveral MonthsChopped
  • Melons – Watermelon is the largest member of the melon family. Its rind is the thickest and will take the longest amount of time to break down. Other melons, such as cantaloupe and Honeydew melons, are smaller and are likely to break down in less time. Chopping the melon peels into smaller pieces can still be beneficial to speed up decomposition.
  • Apple Cores – These are much smaller than watermelons but can still take over a month to break down. The core of the apple is very hard and designed to decompose slowly, giving the embedded seeds a chance to grow and thrive. There is little benefit to chopping apple cores up before tossing them into the compost.
  • Banana peels – While these are much softer than watermelon, the fibers that make up a banana peel can take up to a month to unravel and break down. The high moisture content of a banana peel can slow decomposition. Chopping them up and adding dry materials can speed up the composting process for banana peels.
  • Pumpkins – Pumpkins, squash, and other gourds are also great to compost. These large, hard-skinned vegetables can take 2 to 3 months to break down in compost. If you are looking for ways to speed up the process of decomposing pumpkins, chop them up before throwing them in. They don’t have the high moisture content of watermelon rinds, so less carbon is needed to balance the pile.