Mealworms can absolutely be added to soil, and there are a few good reasons why you may want to do this. Mealworms are the larval form of the darkling beetle, and they can provide valuable benefits to soil when used properly. In the opening paragraphs, we’ll provide a quick overview explaining what mealworms are, why they can be useful for soil health, and how to add them to your garden or potted plants. Further details will be provided in the sections below.
What Are Mealworms?
Mealworms are the larval form of the darkling beetle, Tenebrio molitor. The larvae are typically yellowish or cream colored worms that are about 2.5 cm (1 inch) long. Mealworms go through a complete metamorphosis, meaning they transition from egg to larva, pupa, and finally adult beetle.
Mealworms are commonly used as a food source for pet reptiles, fish, birds, and chickens. However, they also serve an important role in the ecosystem as decomposers. In the wild, mealworms feed on decaying plant material like fallen leaves, dead grass, and decaying logs. They recycle nutrients back into the soil as they consume organic matter.
Benefits of Adding Mealworms to Soil
Here are some of the main benefits of incorporating mealworms into garden and potted plant soil:
Enhance decomposition
As mentioned, mealworms act as decomposers in the environment. When added to soil, they accelerate the breakdown of organic matter like fallen leaves, dead roots, etc. This releases important nutrients like nitrogen back into the soil that plants need.
Improve soil structure
The tunneling activity of mealworms helps to aerate and mix the soil. This can improve soil structure, permeability, and porosity to facilitate better plant root growth.
Provide nutrients
Mealworm castings (aka frass or excrement) contain highly bioavailable nutrients like nitrogen and phosphorus. As they feed, mealworms release these nutrients into the soil for plant uptake.
Attract beneficial predators
Adding mealworms can attract predators of common garden pests like beetles, centipedes, ground beetles, and ants to your soil. These predators may help control pest populations.
How to Add Mealworms to Soil
If you’d like to introduce mealworms to enrich your garden or houseplant soil, here are some tips:
Purchase live or dried mealworms
You can buy live or dried mealworms from many pet supply stores or online retailers. Live mealworms are more active but have a shorter shelf-life. Dried mealworms are more shelf-stable.
Add directly to soil
Simply sprinkle live or rehydrated dried mealworms directly onto the top of potted plant soil or over garden beds. Use about 1-2 mealworms per square inch.
Mix into compost
For a more even dispersal, blend some mealworms into finished compost or potting mix before applying it. Use around 2-3% mealworms by volume.
Bury beneath mulch
You can also place a thin layer of mealworms beneath mulch in garden beds. The mealworms will work their way down into the soil over time.
Target mealworms as needed
For houseplants or compact garden beds, you may want to place mealworms right beneath or beside specific plants that need a nutritional boost.
How Many Mealworms Should I Add?
A good rule of thumb is to use around 1-3 mealworms per square inch when top-dressing soil. Mealworms can consume up to half their body weight each day. Keeping the ratio on the lower side prevents excess decomposition.
For a 10-inch potted plant, you would need about 75-250 mealworms. For a 4×4′ garden bed, you may need 500-2,000 mealworms depending on your goals.
Adjust amounts based on factors like soil nutrition needs, season, climate, and plant types. Monitor plant response and soil conditions, adding more mealworms if needed.
When to Add Mealworms
Mealworms can be added to soil throughout the growing season. Here are some optimal times:
Early spring
Add mealworms in early spring to boost nutrition for new transplants or emerging plants. This gives them a nutrient boost before the heavy growing season.
Mid-late summer
Adding mealworms in mid to late summer helps decompose plant residues and replenish depleted nutrients at a time of heavy plant demand prior to flowering and fruiting.
Fall
Applying mealworms in fall allows them to decompose fallen leaves/debris going into winter dormancy and release nutrients for next year’s growth.
Any signs of nutrient stress
You can spot-treat soil around struggling plants by adding a few dozen mealworms to provide a nutritional boost at any sign of deficiency.
Tips for Using Mealworms in Soil
Follow these tips to get the most out of adding mealworms to your planting beds or potted plants:
Protect from extremes
Ensure mealworms have adequate moisture and protection from excessive heat or cold as they acclimate to your soil environment.
Use lower ratios for seedlings
Cut back on amounts for young transplants – excess nitrogen can burn seedling roots.
Pair with compost
Combine mealworm castings with good finished compost to introduce a diversity of nutrients and organic matter.
Loosen/aerate soil first
Loosening compacted soil before adding mealworms allows them to move and tunnel through the soil more easily.
Supplement with leaf litter
Ensure added mealworms have access to sufficient carbon sources like dried leaves or straw to balance the soil biology.
Potential Issues with Adding Mealworms
While mealworms can provide beneficial impacts, there are a few potential issues to keep in mind:
Excess nitrogen
Too many mealworms can release excess nitrogen. This can lead to excessive foliage growth and potential issues like leaf burn, reduced flowering, etc.
Imbalanced decomposition
Rapid mealworm activity without sufficient carbon inputs can deplete organic matter reserves and biologically ‘burn out’ soil over time.
Disturbance of native species
In some cases, introducing high densities of mealworms may impact populations of native beneficial species in the soil food web.
Spread of non-native species
There is a small risk of introduced mealworms spreading within the environment if they are not native to your region.
Plant pest attraction
High densities of mealworms could theoretically attract some plant pests like beetles, though this is usually minimal.
With appropriate use, the benefits typically far outweigh the potential drawbacks.
Frequently Asked Questions
Are mealworms safe for vegetables and edibles?
Yes, adding mealworms to enrich soil is perfectly safe for edible gardens. The mealworms decompose and are not present on the actual vegetables by harvest.
How long do mealworms live in soil?
Mealworm life cycles can vary depending on temperature and conditions. They typically live for several months to a year or more in soil as larva before pupating into beetles.
Can mealworms damage plant roots?
Healthy mealworm populations will not damage live plant roots. They feed only on decaying organic matter. Excess numbers packed tightly around roots may cause some minor abrasion.
Is it better to add mealworms to indoor or outdoor plants?
Both indoor and outdoor plants can benefit from mealworms in potting mix. Outdoor plants have access to naturally higher populations and biodiversity in soil.
Can I find mealworms in my garden naturally?
You may find some ground beetles, mealworms, and related species naturally present in most garden soils. But supplemental additions are often helpful.
Conclusion
Mealworms can serve as a nutritious natural supplement to improve the health and productivity of garden and potted plant soils. By providing organic matter recycling, nutrients, and soil structure enhancements, mealworms boost microbial activity and plant growth. Apply them throughout the growing season, targeting struggling plants or depleted soils as needed. Monitor soil conditions and plant response, and make adjustments to mealworm amounts as required. When used properly, incorporating mealworms into your soil care practices helps build rich, living soil to grow healthier, more robust plants.
