Few things say “October” like the plethora of pumpkins that are visible nearly everywhere you go. Outside (and inside) grocery stores, on porches and window sills, at farmer’s markets and roadside stands.
Tis truly the season of this iconic cucurbit.
There’s no doubt that for many of us - here in North America at least - the sight stirs feelings of joy and nostalgia, but for a lot of veteran vermicomposters there is an extra feeling of excitement and anticipation.
Why? Because pumpkins are one of the best worm composting feedstocks on the planet!
They also happen to be a very healthy food for humans, but alas, most of the countless millions of pumpkins grown in North America don’t ever make it into soups and pies, or into any sort of composting system. According to an article in The Atlantic, more than 1 billion pounds of pumpkins get tossed every year in the U.S. alone. Most of them end up in landfills, where they decompose anaerobically, releasing methane (a greenhouse gas far more potent than CO2). Here in Canada, the trend seems to be very similar, just on a smaller scale.
We happily endorse the idea of using a lot more pumpkins for tasty recipes - even feeding them to livestock - but none of them (or their “guts”) should be ending up in landfills.
And of course, that’s where composting comes in!
Pumpkin Composting Best Practices
As great as pumpkins are for composting, especially worm composting, it’s important to be aware of several key points:
- There is a lot of (nutrient rich) material in even a single, medium sized pumpkin
- Pumpkins are mostly water
- Once the decomposition process starts, pumpkins can break down quite quickly, releasing a lot of that nutrition and water.
- Pumpkins typically contain a lot of seeds.
So, it’s important to be properly prepared before going too crazy with your pumpkin composting efforts.
- Having someplace to store any surplus of pumpkins that aren’t fully intact (luckily, the cool weather at this time of year, in many locations, can help with outdoor storage), and/or you have some composting friends to share your bounty with!
- Making sure you have lots of bedding materials (and ideally, “living materials”) on hand. In small to medium sized systems, dry absorbent bedding like shredded cardboard can be especially helpful for balancing the moisture released from the pumpkins.
- Harvesting the seeds for food, or doing something to kill them (eg cooking, hot composting), or simply preparing yourself for the arrival of lots of “volunteer” plants (this can actually be quite fun in outdoor beds, and has resulted in some of the most interesting - and surprising - crops of pumpkins we’ve ever grown).
Layered Systems - Perfect for Pumpkins?
A great home-scale option is the GeoBin (be sure to check out “Setting Up Your GeoBin for Worm Composting Success”), since it is very easy to set up and maintain, and it has a surprisingly large maximum capacity. Other backyard composters, or even basic trench/pit systems can also work well.
NOTE: One small perk of not using worms in a layered system is that you can add even more pumpkin wastes at once. Remember, with outdoor fall worm composting systems, we don’t want to add food materials too far up, since this can draw the worms up and increase the risk of them freezing once the really cold weather sets in. A lot of food materials in this type of larger system can also lead to some pretty serious heating early on, which can be another hazard for your worms.
A Super Basic Layered Approach
If you have a large supply of fall leaves (and/or other bulky bedding such as wood chips) and lots of pumpkins to deal with at once, simply building up a heap (or using a GeoBin or cage system) with alternating layers of these materials can be a very simple way to put the pumpkins to use quickly, and to end up with a really nice mix that can be added to other systems or (eventually) even a decent compost. We recommend laying down multiple layers of brown corrugated cardboard (even flattened boxes would be great) as your base layer, since this will soak up a lot of the moisture dripping down, and leave you with another really nice material that can be added to your vermicomposting systems. Also, be sure to make your bedding layers much thicker than your pumpkin layers, as you set up the system.
Using Pumpkin Wastes in Smaller Worm Bins
Pumpkin can be a great food material for regular worm bins, but a lot more caution is warranted (than in larger, layered systems). All that nutrition and moisture can lead to a variety of issues if you’re not careful.
Here are some guidelines to consider:
- Don’t get over-ambitious or impatient - never assume your worms will process even a single pumpkin - let alone multiple pumpkins - in a specific amount of time. Start with modest amounts and see what happens.
- Effective storage will be even more important - if you need to keep a surplus for an extended period, it’s important to have a location that is cool or cold. Smaller quantities can be kept in a fridge or freezer, but as touched on earlier, outdoor temps in many locations at this time of year may be cool enough to greatly slow down the rotting process. Use the jack-o-lanterns, and any that are broken up, first, since intact pumpkins will tend to keep a fair bit longer.
- Use outdoor systems like regular backyard composters (or other layered systems) for excess materials that can’t be stored - if you do have more pumpkin waste than you can use or store effectively, simply tossing them (ideally smashed up a bit) in a regular composter, or even burying them in your garden can be a good option.
- Chop up your pumpkin pieces really well - intact pumpkins are great for storage, but once it is time to use as a worm food, chopping/grinding/blending can be important for speeding up the breakdown process (larger chunks work well in cases where you are looking for more of a slow-release process, though).
- Balance your pumpkin feedings with deposits of dry, absorbent bedding materials and, ideally, living materials (LMs) - absorbent bedding and LMs will help to lock in moisture and nutrients released from the pumpkin, and greatly boost the population of decomposer microbes (in the case of LMs, specifically).
Refer back to our general pumpkin seed recommendations - if you do add pumpkin “guts” (with viable seeds), don’t be surprised if the seedlings literally knock the lid off your bin. These plants can simply be yanked up and dropped back in as an additional food source for the worms.
Pumpkin Parties, and Other Next Level Ideas
Although most of us can likely “do our part” to keep at least a handful of pumpkins out of the landfill, some of us have the space and resources - or even simply the initiative - to do more! So, we wanted to include some bigger ideas for all you keeners out there.
Firstly, it’s important to make sure you either have the land and resources to handle a huge supply of pumpkins, or that you can partner with one or more people, businesses, or organizations that do.
Become a pumpkin collector - even just driving around and gathering pumpkins that have been kicked to the curb after Halloween can yield an impressive supply.
Organize local pumpkin collection drives - when you actually educate people about the value of composting pumpkins, you can get a lot more people interested and excited about helping out, likely inspiring a lot more change as a result.
Or, really go big, and…
Organize/host a pumpkin party or festival - maybe even include “smashing” or “launching” to make it more fun (just make sure there is a clean up plan, and that all those amazing scraps get composted). This would be a great opportunity to hold pumpkin composting, cooking (etc) workshops as well.
Pumpkins add a lot of joy and fun to the fall season - there’s no doubt about it - but it’s clear that more responsibility needs to be taken for all the resulting “wastes” (actually an amazing resource) left over at the end of the season.
Various forms of composting, especially the approaches using worms, offer a fantastic way to convert a lot more pumpkins (along with other bountiful fall resources, like fall leaves) into beautiful black gold!
We hope this article helps you get (even more?) pumped about pumpkins, and eager to put them to good use this season!
The Duncan Pumpkin Pick-Up Patrol!
Have pumpkins to get rid of in Duncan BC? Let us know and we’ll pick them up for our worm herd!
Helpful Related Resources
- Fall - A Great Time to Get Your Backyard Composter Going!
- Setting Up Your GeoBin for Worm Composting Success
- Next Level Backyard Composting - Fall Prep
- Living Materials
- Bedding - The Most Important Material in Your Worm Bin?