Basic Care Guidelines for Your Worm Bin

Tips for Storing Your Worms
Worms have a range of temperature that they generally prefer (65 and 75 degrees Farenheit). Exposing your worms to temperatures outside of their preferred range for any longer than necessary is not recommended.

  • Preferred temperature range: Between 65 and 75 degrees Farenheit (F)
  • Less preferred temperature range: Between 55 degrees and 85 degrees Farenheit (F)
  • Temperatures to avoid: Below 40 and/or above 90 degrees Farenheit (F)
  • Light requirements: None – they prefer dark areas and do not require light to live
  • Humidity: Normal ambient room humidity throughout the seasons are OK.
  • Placement: Place your worm bins in areas that are within reach, easy to access, or otherwise conducive to regular maintenance. Under the kitchen sink, in a pantry area, or basement areas are examples of areas where people sometimes keep their worm bins.

For more details, see the Notes area below.¹

The worm “bedding” is the material that provides habitat for the composting worms. When other food is not available, worm bedding also serves dual purpose as a food source. It should help to remember that compost is a composite (a “mixture”) of materials and worm castings. A worm bin may contain food at varying stages of decomposition as well as castings that contain microbes that help break food down as well as worm bedding that is also in varying stages of material breakdown.

For best results, keep the worm bin bedding moist, but not wet.²

Frequency. Some people choose to feed their bins nearly every day. Others choose a more relaxed weekly feeding schedule. Both of these approaches can work as long as you, the composter, do not overfeed your bin or neglect to feed your bin for too long. The appropriate frequency of feeding depends on at least the following four factors:

  • The number of worms per bin.
  • The size/age/health of the worms.
  • The size of the bin.
  • The type of food you are feeding your worms.

Type of food material. The types of food material you add to your bin is important as the frequency of feedings. A cooked potato chunk will decompose more quickly than a raw chunk of potato. Cooked rice will decompose faster than dried-out moldy rice. When you know the physical characteristics of the materials you add to your bin, you will be able to calculate the time it will take for your worms to breakdown the food over time.

Important: Please remember that while there are reams of scientific research that confirm the benefits of worm compost, there is a part of composting that is also part art or craft. That is, some well-meaning sources will insist (wrongly!) that one pound of worms (or about 1,000 worms) will automatically and always consume exactly one pound of food per day. This general rule is one of the guidelines that appears to have become gospel according to some worm experts, but it is simply not true. When composting indoors, it is much better to allow your worms to digest their food over time and wait until the food you feed them becomes unrecognizable rather than feed them one pound a day whether or not your bin can handle it. By waiting for the worms in your bin to digest what you feed them, you help to avoid a backlog of food waste that can quickly produce overly wet and slimy conditions that may lead to a lack of oxygen, stinky worm bin, and ultimately dead worms.

Monitoring pH. Worms prefer a pH between 6.0 and 8.0. That means they can tolerate a certain level of acidity, but they prefer neutral (7.0 pH) to slightly basic (7.5) pH bedding. You can help your bin maintain a proper pH by adding calcium carbonate to the water you feed your bin.

So, what this means is that if you use coir or Canadian sphagnum peat moss as part of your bedding, you may help offset the slight (and natural) acidity of these solid materials by adding a small amount of calcium carbonate. Calcium carbonate, when dissolved in    are used as part of the bedding, you can add a small amount of calcium carbonate to buffer any acidity that may be present in the bedding material.


Worms breathe through their bodies. They need moisture to absorb oxygen through their skin. However, worms are not aquatic! The poor dead worms we’ve all seen who got trapped in the rain puddle in some pothole in the street are proof that worms can survive underwater momentarily….but not for extended periods of time. If at any time you are concerned about overwatering, try watering your bin with a mister bottle. And mist the bedding and the worms as you turn them over with your hands.

Finishing Your Compost
The process of “finishing” your compost takes time, and the process of converting 2 dry gallons’ worth of peat/coffee/food waste using 500 worms may take a month longer than if you used 1500 worms. At the same time, the longer you let a bin go without food, the more you expose the bedding in the bin to worm feeding. Well processed worm compost should have a dark, crumbly, and “clay” topsoil characteristic. A good way to develop compost is to expose soil to worms and let the worms “finish it off” for a few extra weeks beyond the initial three-week exposure to worms.


1. Regarding temperature. For best results, store your worms in a cool dark place between 65 and 75 degrees Farenheit. The bedding in a worm bin buffers the changes in the ambient air temperature outside of the worm bin, so you don’t need to monitor indoor temperature too carefully during the warm seasons; redworms would naturally experience a changes in temperature in their native outdoor habitat. It is more important to avoid exposing the worms in your worm bin to extreme temperatures. In Minnesota, it is recommended to keep redworms indoors during the winter to prevent them from freezing. If bringing them in doors is not a possibility, you may try to store them outside by burying them at least three feet deep within an outdoor compost pile – preferably one that is next to a heated building or other structure that has sun exposure. Outdoor overwintering of redworms is not guaranteed, and is not recommended. In the summer, avoid storing your worms in an unventilated garage or leaving them in an unventilated vehicle on a hot summer day.

2. The general rule of thumb is that you should be able to squeeze a small drop of water when you squeeze the bedding; this level of moisture would be the same amount of moisture you would expect in a slightly (but not overly) wrung-out sponge. See the moisture graph for a visual example of how to gauge moisture in a bin.

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