This is a question we get quite often. Recently, one of our customers, Judith, emailed that her vermicomposting European Nightcrawlers weren't getting any bigger. She not only uses the worms for vermicomposting kitchen waste, but she also uses the worms for fishing. She's had these worms for over a year now. Even though she's not into worm farming as a business, the answer to her vermicomposting problem is same.
There are several reasons that worms stay small and don't grow into bait size. Below is a summary of these reasons with remedies.
1. The worms are too crowded.
In order for worms to reach maximum size, they need plenty of room. This is particularly true for young worms. In Judith's case, her worms have been breeding and laying egg capsules all along. These egg capsules have hatched and her vermicomposting bin is most likely getting over-crowded.
My advice to her was to split the bed into two. Since she's not interested in have more than one vermicomposting bin or in going into the worm farming business, she should give them away. The worms must be divided and the population reduced in the existing bed for her worms to grow.
2. The bedding is "too old" and/or compacted.
If she hasn't changed out the bedding recently, her vermicomposting bin bedding has undoubtedly been converted almost entirely to worm castings. An over concentration of worm castings is unhealthy for the worms and eventually kills them.
The good news is these worm castings are an excellent source of fertilizer for gardens and flowers. She can take her worms out of the bedding, transfer them into fresh bedding and broadcast the castings onto her plants. If the worm castings aren't needed right away, they store very well and will keep until needed.
3. There's not enough food to go around.
The more worms in a bed, the more food is required. When worms are growing, they need an "all-you-can-eat" food supply. In Judith's case, she wants worms to grow to bait size. An option she could consider is to pull out the mature worms, put them into a separate bed and feed them a rich worm feed such as FRM's Worm and Cricket Food (you can find it at some feed and seed farm stores.
This option is one you will be using in your worm farm business if you are going to serve the fish bait business. Feeding your worms in this way is tricky and can lead to problems (such as "protein poisoning") if not done correctly. There are complete instructions on fattening bait worms in my upcoming "Worm Farm Manual".
In a nutshell, feed rich, grain based worm feed only in the amount that the worms can consume in a 24 hour period. The trick is to give them all they need without overfeeding.
4. Worm Farming Secret: Increase the microbe content of the bedding and added food.
One of the surest ways to not only grow big worms, but also keep your worms healthy, is to spray you worm bedding and added food with a weak mixture of VermaPlex® (a liquid soil inoculant fertilizer made from worm castings) and water (80 parts water to 1 part VermaPlex®).
Worms digest food by "following behind" microbes. The microbes basically predigest the food, thereby facilitating the worms' digestion. Worms absolutely must have a healthy amount of microbes in order to process food.
The good news is, microbes show up automatically in food waste. By adding the VermaPlex® spray, you are speeding up this process and guaranteeing the worms have plenty of help with their digestion process. Read about the application of VermaPlex® to your worm beds here "Worm Farming Tips #2".
In summary, provide amply room, food and microbes for your worms to grow big and fat. Please post any questions or problems you may have about growing bigger, better worms.
VermaPlex® : As a worm bed enhancer.
European Nightcrawlers: By far the best fishing bait worm.
Red Worms: The premier vermicomposting earthworm.
Worm Farm Manual: A Step By Step Guide To Raising Earthworms.