Urban Worm Bag Review – More Airflow for Better Compost

The Urban Worm Bad is one of the most breathable worm composters
One of the most breathable worm composters

Airflow is key to producing high quality vermicompost. The Urban Worm Bag is one of the most breathable worm composters. The aerobic design is similar to the old Worm Inn worm bag which is no longer available.

Your worms live inside the bag and the composting system works as a continuous flow design. The cycle is add food and bedding on top and collect worm castings from the bottom.


  • Larger capacity / surface area
  • Very breathable fabric / lots of airflow
  • Top notch support / excellent customer service
  • Zipper bottom is marine-grade
  • Product comes with a lifetime warranty
  • No worms in the castings
  • Robust frame


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The Urban Worm Bag versus the Worm Inn – What’s the difference?

The Worm Inn (inset) is similar in design to the Urban Worm Bag.
The Worm Inn (inset) is similar in design to the Urban Worm Bag.

The Urban Worm Bag is an evolution of the Worm Inn, addressing many of the complaints with the old product. I asked Steve, creator of the Urban Worm Bag, whether his creation has any relation to the Worm Inn. This is what he said:

“The Urban Worm Bag is definitely inspired by the Worm Inn. I thought (and still think) that the Worm Inn was an excellent product; however it is no longer in production. It lacked a frame, so I wanted to make sure the Urban Worm Bag was a more complete solution. I also didn’t like the loop attachments of the Worm Inn as I felt they did not spread the weight of the Worm Inn evenly on the frame. My fabric tunnelling helps distribute the weight evenly on the frame.

I also thought the Worm Inn breathed too well, so I made sure that the top of the Bag was also fabric, rather than than a mosquito net mesh.

I started out with Version 1, which only had a zipper at the bottom, not the drawstring, like the Worm Inn. However, the zipper, despite being marine grade, calcified more than I expected. This made opening the zipper difficult. This summer, I introduced Version 2. Features include a Worm Inn-style drawstring, but inside the zipper bottom. This protects the zipper, also allowing the bag to be operated with only the drawstring bottom. This is key for helping release excess moisture through the bottom. For beginners, I recommend keeping the zipper open to release any excess moisture until things stabilize. This also promotes a more aerobic vermicompost.”

Steve, Urban Worm Company, December 2018

In Summary

In summary, the Urban Worm Bag is different to the Worm In in the following ways:

  • Includes a frame. The Worm Inn required a DIY frame.
  • The worm bag connects to the frame via fabric tunnels instead of loop attachments. This helps to distribute the weight more evenly on the frame
  • The top of the worm bag is fabric instead of a mosquito net mesh. This helps to maintain moisture levels.
  • New versions have a drawstring and zipper opening at bottom, instead of a drawstring


Urban Worm bag drawstring opening at the bottom
Urban Worm bag drawstring opening at the bottom

The system has a continuous flow design. You feed from the top, and collect compact worm castings from the bottom. The size of the worm bag is very large, with plenty of surface area.

You can expect to start harvesting after 4-5 months. The castings near the bottom will compact under the weight. Unzip the bottom and the castings will fall out. As composting worms are surface feeders, the worm castings near the bottom of the bag will be free of worms.

The frame and corners are strong and robust.
The frame and corners are strong and robust.

Adequate airflow is required in order product high quality worm compost. And this is where the Urban Worm Bag shines. Most commercial worm bins are made out of recycled plastic which is not very breathable. The Urban Worm Bag on the other hand, is made out of a breathable fabric. This creates the ultimate aerobic worm composter.

It also has a surprisingly strong and robust frame.


This worm farm has an unusual hanging bag design. Let’s be honest, it looks like a backpack on stilts. And so it’s not immediately recognizable as a worm farm. Don’t let it’s odd appearance fool you. You can tell a lot of effort has gone into creating a quality product.


The Urban Worm Bag includes parts for the frame.
The Urban Worm Bag includes parts for the frame.

It comes neatly packaged in a box. Unlike the Worm Inn, it includes a frame. Assembly is straightforward and should take no longer than 5 minutes.

Air Ventilation

You wont find a better worm composter for air ventilation than than Urban Worm Bag. The worm farm breaths through it’s fabric material. So this is a big tick.

On the other hand, too much airflow can be a double edged sword. Take some time to get the moisture levels under control. So make sure you add foods with sufficient moisture content to avoid any problems.

Too much moisture can make the worm bin smell. The Urban Worm Bag is better suited to indoors or undercover if possible. As rain will increase the moisture.


You will need to place a bucket underneath the bag to collect any excess liquid. The Urban Worm Bag evaporates moisture quicker than other worm bins. Excess liquid will be minimal.


This worm farm has a large capacity and surface area compared with than worm bins.


Competitively priced in the middle price range. You can find the latest price and offers here.

Urban Worm Bag Review Conclusion

Given the sheer size, aerobic benefits, excellent customer service and thought put into the design, this worm farm provides very good value.

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