Worm Care Guide
Want to learn how to be a better worm parent? Check out the guide below for composting with worms.
Top 5 tips:
Keep bedding damp! When bedding gets dry, add water slowly. A layer of damp newspaper or coffee filters on top helps seal in moisture.
Break or tear food into small pieces to encourage faster processing.
Bury food below the top layer of bedding.
Try not to overfeed. Check if worms are eating the food they already have before adding more. (You can freeze excess scraps!)
Keep the bin indoors or in the shade, never in direct sunlight. Ideal temperature is 55-75°F (never below 32°F or above 90°F).
Where can I buy worms in San Diego?
For vermicomposting bins, the type of worms you need are “red wigglers” or “red worms” (Eisenia foetida). These worms, as well as other composting supplies, are available for purchase at Solana Center through the online store. Most garden centers sell them as well.
If you are starting a standar size Wriggly Wranch Worm Bin, you will need about 1 lb. of worms.
What should I feed my worms?
Worms LOVE to eat:
Fruit Pieces & Peels (Woem favorites: Bananas, Melons, Avocados)
Vegetable Pieces & Peels Coffee Grounds
Tea Bags Egg Shells Shredded Newspaper
Worms DISLIKE (but will eat SMALL amounts of):
Citrus pieces & peels (Ex: Oranges, Lemons, Limes)
Spicy Foods (Ex: Jalapeños, Onions)
Plain Bread, Pasta, Cereal, Leaves & Yard waste
Worms CANNOT eat:
Meat
Fish Dairy Products (Ex: Milk, cheese)
Oily Foods Salty Foods Glossy/Shiny Paper
How should I take care of my worms?
Daily Maintenance
Collect scraps. That’s it! They are really that low maintenance.
Food for your worms
Fruit Pieces & Peels (Worm favorites: Bananas, Melons, Avocados).
Exceptions: NO Citrus or Pineapple. Because worms live in a confined area, it is important to be careful to keep these types of food out of the bin because it can harm them. Worms breathe through their skin and certain foods will irritate or prevent that process. For instance, the natural chemicals and acidity in citrus peels and onions can kill worms and other microorganisms, which can slow down decomposition rates in your bin. A well-maintained worm bin should have a pH measurement between 6.0 and 7.0, so it is best to play it safe and not include too many acidic foods. Foods that are too fatty or oily such as dairy, pasta, or bread can also interfere with the worm’s skin.
Vegetable Pieces & Peels Coffee Grounds
Exceptions: No onions
Tea Bags, Egg Shells, Shredded paper
They are happiest on a vegetarian diet. Scraps that you would normally put down the garbage disposal can be put into your worm bin. Your worms will eat some foods faster than others – they have preferences just like we do. Worms need calcium to reproduce and grit to grind up their food, so add eggshells every once in a while.
Worms love to eat:
Fruit Pieces & Peels
Vegetable Pieces & Peels
Coffee Grounds & Filters, Tea Bags & Strings (no staple)
Egg Shells
Shredded Newspaper
Worms eat small amounts of:
Citrus Peels & Pieces
Spicy Foods (Hot Peppers, Onions)
Plain Bread, Cereal & Pasta
Leaf Litter
Worms don’t like:
Meat & Fish
Dairy Products
Oily Foods
Salty Foods
Woody Yard Waste
Glossy/Shiny Paper
Weekly Maintenance
Check the moisture level of the bedding. If it is dry, spray with water or add more coffee grounds. If too wet, you could add a little bit of dry shredded paper (or a ripped up paper towel).
Bedding, which can be made of shredded paper, coconut coir, cured manure, or dry leaves, is an absolute necessity in your worm bin. Supplying your wiggly workers with bedding has a number of benefits:
Bedding provides a light, fluffy medium for worms to move through, which helps keep air moving through your vermicomposting system. The bedding should also be lightly moistened (aim for the moisture of a rung-out sponge), which will help maintain the damp environment your worms need to survive.
Many fruit and vegetable scraps become acidic as they decompose, which can have negative consequences for worm health such as protein poisoning, also known as “string of pearls” or sour crop. A generous layer of bedding, along with some finely crushed eggshells, helps buffer pH and prevent acidic conditions.
By themselves, fruit and vegetable scraps will putrefy as they break down, creating a slimy slop. Not only will this limit airflow, but it also tends to stink! A layer of bedding will absorb and mix with the decomposing kitchen waste and keep air moving, resulting in an earthy smell.
Rotting fruits and vegetables may not smell pleasant to us, but the smell is irresistible to the most common worm bin pest, fruit flies. By providing plenty of bedding in your bin and always burying your food waste under a layer of bedding, you can limit the possibility of a winged invasion.
If you have a Wriggly Wranch, Can-O-Worms, or similar multi-layer worm bin, you should put bedding, worms, and food waste in the upper layer(s) of your worm bin, which should have holes in them, and leave the solid bottom layer of your worm bin empty. This will allow any excess moisture to drip from the upper layers containing the worms down to the solid bottom layer. This liquid, called leachate, can be drained off and used to fertilize non-edible plants only.
We are often asked if adding shredded mail and computer paper to the worm bin is toxic because of the ink. The inks used today in newspapers, boxes etc. are non-toxic and are readily broken down through composting. However, the see-through address windows in the envelopes don’t break down and will remain in the finished compost. One can tear out the window or instead put that type of envelope in the recycling. Also, thick, glossy, colored paper doesn’t break up or decompose easily. Don’t forget to add shredded cardboard and egg cartons — it is a favorite worm food and will disappear quickly!
See if your worms are hungry. If there is no leftover food, feed them! Bury the food with a couple inches of bedding.
Check the bottom tray for liquid and escapees. The liquid will start to smell pretty quickly, so you’ll want to wash it out.
Moisture content is very important when composting with worms. This is because your red wigglers breathe through their skin and need appropriate moisture to do so. Often times the materials you add will give your bin moisture, but you will likely still need to add water to obtain the appropriate amount (especially with warmer weather).
To check your moisture content, reach into your bin and grab a handful of the contents. It should feel like a wrung out sponge with a few drops of water.
Too dry: A good thing to have near your worm bin is a spray bottle, especially when the weather is a bit warmer. Lightly spray the contents of the bin until it reaches the “wrung out sponge” moisture content.
Too wet: Add some dry shredded paper. This will soak up the excess moisture and your worms will eat it too! Be sure to double check your collection tray as well. If your collection tray is overflowing, it may be adding extra moisture to the bottom level, causing the bin to become too wet.
Keep the lid on the bin to protect the worms from light, to prevent escapees, and to keep flies/pests out.
Why are my worms climbing out of the bin and trying to escape? If your bin becomes too acidic, too moist, too dry, too compact, full of rotting food, full of food they don’t like, too warm, too cold, or they just organize an expedition, your worms can attempt an escape from your bin. Oftentimes, when temperature conditions are not ideal (optimal is 55-75 degrees Fahrenheit), the worms will make an attempt to escape the situation. This thwarted escape plan (if your lid is on tight) ends up with many worms in your bottom collection tray or on the sides and lid of your bin. For beginning worm caretakers, a common mistake we’ve noticed is to overfeed the worm bin before the worms have acclimated to their new home. Resist the urge to toss it all in! Be patient in the early stages of your worm home and observe their behaviors. You may notice a rancid smell when there’s too much food: this is considered anaerobic decomposition (without air).
Some pro tips:
Cut your food scraps into small pieces (the smaller the pieces, the easier for our team of decomposing microbes like bacteria, fungi, archaea, etc. to break down the organic material). This allows for food scraps to quickly decompose and accelerate the process.
Keep the moisture damp, but not wet. We encourage the contents to feel like a wrung-out sponge!
Bury your food waste. This prevents outside pesky invaders from overrunning your worm bin (e.g., fruit flies) and laying eggs on freshly exposed decaying organic materials.
When in doubt, add more bedding to bulk up the bin and create balance between your food waste and your bedding material. Some options for bedding include shredded newspaper/office paper, soggy cardboard/egg cartons, and coconut coir.
In the event that your worm bin has just gotten too wet and juicy, the bottom bin may have collected some rogue worms and a dark brown liquid, or leachate. To rectify this situation, add water to the collected liquid in order to dilute the sediment and ease its flow through the sieve. Then strain the liquid through a sieve or small holed colander, rinse the collection tray out and reassemble the worm bin. Add the worms, collected in the sieve, back into your top working tray. If you clean out the bottom bin regularly you can save all your wayward worms and keep the liquid fresh and in top condition.
Dilute the liquid with 5-10 parts tap water before adding to your garden. Remove the chlorine from tap water by letting it stand in the sun for several hours.
What should I do with my worms while on a trip?
Depending on the length of your trip, you will likely not need to do anything at all. Even a new population of worms only needs to be monitored every few days to assess how much food was eaten, moisture levels, and whether they need more food. If you’re planning to go out of town for the holidays this year, regardless of how long your trip may be, consider following these steps prior to embarking on your adventure:
Make sure they have a good amount of bedding at a proper moisture amount. Instead of throwing lots of kitchen scraps into your worm bin to make up for your absence, which could disrupt the pH of your bin or even smother your worms, make sure you leave your worms an adequate amount of moist bedding– at least a six-inch layer. Worms can live off bedding material such as shredded paper, coffee grounds, or dried leaves, for a month or longer! Of course, you can still add kitchen scraps before you head off, giving them about twice what you’d normally feed your worms weekly.
Ensure your bin is in a shaded area. Worms do best at temperatures between 55°F – 79°F. Temperatures above 85°F can be lethal.
If you are leaving during the wintertime, consider insulating your bin with a blanket or soil, or bring the bin inside in case of cold snaps. While worms do better in colder temperatures than hot, temperatures below 32°F can devastate your worm population.
If you’ll be gone over a month, consider recruiting a “worm-sitter” to visit and add some food scraps after a few weeks. You can even prep some kitchen scraps in a bag or container in the freezer for easy feeding; frozen scraps can be added straight to the bin. Just make sure your sitter knows to cover the kitchen scraps with bedding so you aren’t greeted by flies upon your return!
When you return from your trip, provide your worms with some fresh kitchen scraps and they’ll be happy to see you!
Harvest Time:
(Every 3-4 months) – When the bedding material is no longer identifiable – it will look like soil
A couple weeks in advance, start feeding your workers only in one corner. They will then mainly hang out there.
Right before you harvest the castings, prepare the new bedding. Shred a heck of a lot of paper and mix it with coffee grounds until it is the texture of a wrung-out sponge. Stir in some crushed egg shells.
To harvest the worms, simply take the now digested bedding material out of your worm bin, leaving the feeding corner. There are a variety of ways to harvest worm castings. Here are a few of the most common methods:
The Migration Method
Worms will follow food scraps, and given a little time, can actually be guided to sort themselves from their castings. The key is to STOP feeding the area you wish to harvest, and ONLY add food to the area with fresh bedding. The worms will travel to the new area in search of food, leaving you with (virtually) worm-free castings to harvest. After harvesting, replenish the now-vacant side or tray with new bedding and food scraps to restart the process. Isn’t it nice when the worms do all the work?
There are two general ways to implement the migration method:
If your worm bin is comprised of a single tray, the worms will need to travel horizontally to one side of the bin. Move material to be harvested to one side of the bin, and replenish the other side with fresh bedding and food scraps.
If you want to utilize mulitiple trays, the worms will need to travel vertically (either up or down) to a newly-prepared tray with fresh bedding and food scraps.
PRO: This easy, self-contained process is mostly hands-off; useful for anyone who is queasy about handling the worms or getting a little messy.
CON: Expect waiting 1-4 weeks (depending on the size of the bin) for a good proportion of the worm population to relocate to their new home.
The Photosensitivity Method
Worms are highly sensitive to light, and will readily move away from light sources. By strategically introducing light, worms can be guided to burrow to a desired location, allowing for easy collection of the remaining castings. If outdoors, choose a sunny location to work; if indoors, place the piles under bright light for the entire process.
There are two general ways to implement the photosensitivity method:
The Volcano/Cone Method
The Volcano/Cone Method is practiced by emptying out the bin contents onto a stable surface (that you don’t mind getting dirty) and sorting the castings into loosely-packed, cone-shaped piles. The worms will continually burrow away from the edges to escape the light, allowing you to scrape the worm-free castings off of the tops and sides of the piles. Take a 15 minute break after each round of castings removal to allow worms time to move inward. Repeat this process several times until only small piles of worms and castings remain; these can be placed into a bin with fresh bedding and food scraps.
The Burlap/Filter Method
The Burlap/Filter Method is practiced by first emptying out bin contents into a temporary holding area, then immediately replenishing the empty bin with fresh bedding and food. Place a piece of damp loosely-knit burlap (or any mesh cloth with openings large enough for worms) over the bin, allowing it to hang over all edges. Spread a thin (approx. 1 inch) layer of castings on the burlap. Wait for at least 20 minutes for the worms to burrow away from the light source, directly into their new home. Worm-free castings can then be removed from the top of the burlap. Repeat this process until all bin contents have been separated.
PRO: Fairly organized and immediately gratifying processes that allow the harvester to multi-task.
CON: Not for the easily distracted; worms that are left in the sun for too long will not survive the ordeal!
The Free-for-All / Meditative Method
If you love getting to know your worms up close and personal, this slower-paced, hands-on style may just be the method for you.
There is essentially no planning or technique required with this method; simply dump out the bin contents (probably onto a surface you don’t mind getting dirty) and remove the worms from the castings by hand. Worms should soon after be placed into a bin or tray with fresh bedding and food scraps. While less organized than other methods, this strategy is perfectly effective as long as you don’t mind spending a little extra time sorting through castings.
PRO: Immediately gratifying, lots of fun for those who enjoy handling the worms, and a great activity for kids!
CON: Not a recommended method for those in a hurry.
Add new bedding to the bin.
Check the harvested material for stragglers (and if you want, for cocoons. If you check the picture below, you will see a cocoon at the base of my thumb). Do what you will with the worm castings, place any stragglers in the new worm bedding.
Are Super Dense Worm Castings Still Usable? Yes! Thick, fudgy castings are as viable a soil amendment as finer, more granular castings. Denser castings may, however, necessitate some adaptations to traditional methods of harvest and application.
First, an important distinction: – Castings/Vermicast = Worm manure – Vermicompost = A mixture of worm castings and decomposed or partially decomposed organic matter that has not been digested by the worm.
Worm castings are naturally a more concentrated substance than other types of compost, including vermicompost. Castings are generally characterized by their dark brown color and soil-like appearance, however, color, texture, and density will vary according to the inputs and care regimen of each bin. Thick castings signify a greater density of castings to vermicompost, but very thick castings tend to be a result of allowing excess moisture to build up in the bin.
The type of bedding used in the worm bin will affect the ultimate texture of the castings; for instance, coconut coir bedding will produce fluffier castings than shredded paper bedding.
The moisture content of the bin is critical in determining the final consistency of the castings: lower levels of moisture (and regular aeration) will produce lighter, fluffier castings, whereas allowing excess moisture to remain in the bin will clump materials and generate heavier, denser castings.
Clogged drainage holes are characteristic of a bin holding excess moisture. When drainage holes get stopped up with castings, standing water in the bottom of the bin causes the (highly-absorptive) castings to become very fudgy, thus making harvesting more difficult.
Castings that are left in a bin too long (and undergo multiple instances of digestion) will become increasingly condensed. With time, this over-processing produces less nutrient-rich castings, less active worms, and can even become toxic to the worm community. If this is the case, castings should be harvested as soon as possible.
When it comes time to harvest a bin with high-density castings, drying out fudgy materials is not recommended, as the process will be time-consuming (due to the high moisture content of the castings) and will likely produce hard chunks that are difficult to mix into the soil. Instead, use your castings straight out of the bin, or consider making worm tea out of some of the castings.
Castings are generally mixed into the soil at 4:1 or 5:1 soil to compost ratio, but it is worth noting that dense castings can be mixed into soil at smaller ratios, as thick castings have a high moisture-holding capacity, but are less permeable than fluffy castings or vermicompost.
What are the white things in my worm bin? Spot something unfamiliar in your worm bin? Don’t fret, you are likely to find many organisms other than worms in your worm bin! Like backyard composting, you will see a diverse, interdependent community of large and small organisms. They serve as food for each other, clean up each others’ waste, convert materials into forms that other organisms can utilize, and control each others’ populations.
No legs? Slender, thread-like body? Probably a pot worm! These creatures are often mistaken for newly hatched red wiggler worms because of their size. However, young red wigglers are a reddish color because of their red blood. Although related to the larger earthworms, enchytraeids do not have hemoglobin-based blood and remain white throughout their lifetime.
No visible legs? Thicker, rice-like body? Probably a fly larva! But don’t be grossed out! Despite their unsavory reputation, even these creatures play a role in breaking down and recycling nutrients back into the soil. Fly larvae are voracious consumers of nitrogen-rich decaying materials, such as kitchen food scraps and manures.
Almost too small to see? Highly mobile, with tiny legs and antennae? Probably a springtail! These 1/16 of an inch critters feed on decaying matter and fungi, so they are also a helpful member of your bin community.
Story Time: Sharing the love of worms. Written by Master Composter and Solana Center Docent, Tammy Churchill
Over the holidays I visited family in Northern Wisconsin. My Master Composting skils were drawn upon as my Mother-In-Law was looking for a solution to divert her food scraps from the landfill when her compost bin was buried in snow and the ground is frozen solid. From my experience volunteering at Solana Center information booths, I knew that not everyone is receptive to having indoor worm bins. Fortunately, she was.
Following the Solana Center instructions, I drilled the requisite air holes in the container and we made up bedding. The mail-order worms arrived when it was only 17 degrees outside. That box was cold! Surprisingly they survived, but it did take a few days for them to unball completely. Delicious food scraps helped with that.
To give more confidence to my Mother-In-Law, I shared this worm care cheat sheet, which is now posted on her fridge. Knowledge is power, plus she knows her personal worm advisor is only a phone call or email away!
