How do I use mealworm frass on my plants?

1. Do I need to compost mealworm frass before using it?

No – you do not need to compost mealworm frass before use. It is already “pre-processed” by the insects and comes in a dry, stable form that’s ready to add directly to your garden or pots. Unlike fresh animal manure, which often must be composted or aged to be safe for plants, mealworm frass is ready-to-use straight out of the bag​.

Mealworm frass is sometimes nicknamed “insect manure,” but an important difference is that it’s much more user-friendly right away. When mealworms digest their food, they break down the organic matter and in the process, a lot of the decomposition work is already done in their gut. The frass that comes out is dry and relatively refined – it doesn’t have big chunks of raw organic material that need further composting. Essentially, the mealworms have already composted the material for you on a micro-scale.

Fresh livestock manures (like chicken or cow manure) often contain high levels of ammonia and can “burn” plants if applied fresh. They also might carry pathogens (like E. coli or salmonella) and weed seeds, so we compost them to stabilize nutrients and kill off harmful organisms. Mealworm frass, by contrast, is produced by insects in clean conditions (mealworms are usually raised on clean grains/veggies and kept dry), so it doesn’t have those pathogen issues. It’s also much lower in ammonia; the nitrogen in frass is mostly organic (in forms like uric acid and microbial protein) rather than raw ammonia, so it’s gentler.

Because frass is dry and ready to use​, you can apply it directly as a fertilizer or soil amendment without any “cooking” period. In fact, storing it in a compost pile could actually cause some of its nutrients (particularly nitrogen) to leach out or gases off, wasting its goodness. You certainly can add frass to a compost heap if you want – it would act as a nice nitrogen-rich input to boost the pile – but there’s no requirement to compost it before putting it around your plants. This is a big convenience advantage: you get the benefits of manure without the hassle of composting or the risk of raw-manure problems. So, feel free to take mealworm frass and simply sprinkle or mix it into your soil as-is. Your plants can start benefiting from it right away.

2. How do I use mealworm frass on my plants?

Mealworm frass is very versatile and can be used in several ways on plants. The main application methods are: top-dressing (sprinkling it on the soil surface around plants), soil mixing (incorporating it into potting mix or garden beds before or during planting), and making a “frass tea” (brewing it in water to use as a liquid fertilizer). You can also use that liquid as a foliar spray after straining. Additionally, frass can be placed in planting holes or mixed into transplant soil, and even used in hydroponic systems after dilution​.

Here’s a breakdown of common application methods and how each benefits your plants:

• Top Dressing: This means applying frass on the surface of the soil around an established plant. You simply sprinkle a small amount of frass evenly around the root zone (the area under the canopy of the plant) and then water it in​. The water helps wash nutrients down to the roots. Top-dressing is great for giving plants a nutrient boost during the growing season. As you water or it rains, the nutrients seep slowly into the soil, feeding the plant over time. Top-dressing with frass also introduces those beneficial microbes right at the soil surface, which can help suppress diseases around the stem base. It’s an easy method – no digging required – and you can repeat it every few weeks as needed.

   

  Mixing into Soil (Soil Amendment): You can mix mealworm frass into potting mix or garden soil, much like you would mix in compost or other amendments. This is especially useful at planting time. For example, when preparing a garden bed or filling pots, you might blend in some frass with the soil so that the nutrients and microbes are well-distributed where new roots will grow. If you’re transplanting a seedling, you can even toss a pinch of frass into the planting hole or mix it with the backfill soil. Incorporating frass into soil ensures a baseline of fertility – the plant’s roots will have access to nutrients as soon as they start extending. It also helps improve the soil structure slightly by adding organic matter. Compared to top-dressing, mixing in is done before or during planting, and it sets the stage for robust early growth. (One tip: when mixing frass into potting soil, aim for it to be a small percentage of the mix – guidelines often suggest on the order of 1 cup of frass per cubic foot of soil, which is less than 1% by volume​.)

   

• Frass “Tea” (Liquid Application): Mealworm frass can be steeped in water to create a liquid fertilizer, often called frass tea. To do this, you’d mix a measured amount of frass in a container of water, let it sit and brew for a while (anywhere from 15 minutes to a few hours; since frass is quite fine, even a short steep can extract nutrients), then strain out the solids. The resulting liquid is rich in soluble nutrients and can be used to water your plants (root drench) or even as a foliar feed. For example, a simple recipe is to add about half a cup of frass to a gallon of water, stir and let it sit, then use that to drench the soil around your plants. This essentially delivers the nutrients immediately to the root zone in liquid form, which can be helpful if a plant needs a quick pick-me-up. If you want to use it as a foliar spray (spraying on leaves), just be sure to strain it very well (through a fine cloth or coffee filter) so no particles clog your sprayer. Foliar feeding with frass tea can give plants a quick nutrient absorption through leaves and might also have a mild pest/disease deterrent effect because of the chitin and microbes contacting the leaf surface. Always use foliar sprays in the morning or evening (not in harsh sun) to avoid leaf burn.

   

• Other methods: You can also use frass in more specialized ways. It can be added to compost tea brews as an ingredient to supercharge the microbial content. It’s sometimes dusted lightly on the soil surface of seedling trays (as a gentle starter fertilizer). In hydroponics (as discussed later in question 9), frass can be used by dissolving it and using the solution. And when planting trees or shrubs, frass can be mixed into the backfill soil to help establish the young plant. Because it’s a dry powder, frass is easy to sprinkle by hand or with a spreader for larger areas like lawns. Really, any way you’d use an organic fertilizer or amendment, you can use mealworm frass – it’s quite flexible​.

   

No matter which method you choose, after applying frass it’s a good practice to water it in well. Watering helps start the breakdown of the frass, carrying nutrients into the soil and activating the microbes. Also, remember that frass is gentle, so you don’t need to worry too much about exact placement – unlike a fertilizer spike or pellet that might burn if too close, frass can even touch plant stems or seeds without harm. Choose the application method that fits your gardening routine: top-dressing is quick for established plants, mixing in is great for new plantings, and frass tea is excellent for a controlled dose or for hydroponic/indoor setups.

3. How much frass should I use?

You generally don’t need a lot of frass to get good results – a little goes a long way. Typical usage rates are on the order of a few tablespoons per plant or a cup or two per several gallons of soil. For example, you might mix about 1 cup of frass per cubic foot of potting soil, or top-dress a garden plant with 1-2 tablespoons of frass (or roughly 1 pound per 20 square feet of garden bed) at a time​. If making frass tea, about ½ cup of frass per gallon of water is a common recipe​. These are general guidelines – you can adjust up or down based on plant needs, but because frass is mild, you have a wide safety margin.

The exact amount of frass to use can vary depending on the plant and application method, but here are some recommendations:

• In soil mix: When mixing frass into potting soil or garden beds, a typical rate is around 1 cup of frass per cubic foot of soil​. In other terms, that’s roughly 1 to 1.5 cups per standard wheelbarrow of soil, or a handful or two in a 5-gallon bucket of potting mix. This works out to be well under 5% of the soil mix (often less than 1% by volume), which is plenty to enrich the soil. This low rate is effective because frass has concentrated nutrients relative to something like compost. After mixing it in, you generally don’t need additional fertilizer at planting time – the frass will supply nutrients for the first several weeks of growth.

   

• Top dressing: For established plants in the ground or large containers, a good rule of thumb is about 1 tablespoon of frass per plant for a small to medium plant, or a couple of tablespoons for a larger plant. In bed terms, about 1 pound of frass per 20 square feet of garden area is a recommended dose​. You can even be a bit more generous if the plants are heavy feeders, since the frass won’t burn them, but you might be wasting product if you greatly exceed those amounts. It’s often better to do moderate but repeated applications (rather than one huge dump of frass) so that the nutrients release steadily. If you’re top-dressing a lawn with frass, you would spread it quite thin – for example, that 1 lb per 20 sq ft guideline can be scaled up to whatever area you have.

   

• Frass tea or solution: When using frass in liquid form, you don’t need much per volume of water. About 1/2 cup of frass per gallon of water is a common mixture for making a frass tea or hydroponic solution​. After steeping, you’d use that gallon to water several plants. If you’re feeding a larger number of plants, you might brew 5 gallons of water with ~2 cups of frass. For foliar spraying, since you’ll be misting a lot of leaves, you might only need a few teaspoons of frass in a quart sprayer (after straining) – often recipes suggest around 1 teaspoon per quart for foliar feeding. Always strain well so you don’t get particles clogging your spray nozzle.

   

• At transplant/seedling: For small seedlings or when transplanting, you use very small amounts – often just a pinch of frass in the planting hole or mixed into the potting soil of a seedling​. That little pinch provides a gentle nutrient boost to get the young plant started. Because seedlings don’t need much nutrition early on, frass’s slow-release nature and small dose ensure they aren’t overwhelmed.

   

• Heavy feeders vs. light feeders: If you’re growing plants that are heavy feeders (like tomatoes, corn, large flowering annuals), you might use the higher end of application rates and reapply a bit more frequently. For example, a tomato plant could get a tablespoon of frass every couple of weeks. For lighter feeders (like many herbs or succulents) or plants in rich soil, you can use the lower end – maybe just a tablespoon once a month. If your garden soil is already fertile or if you’ve incorporated frass at planting, you might not need to add much more later on except for very demanding plants.

One of the advantages of frass is its forgiving nature – since it’s not super concentrated or caustic, using slightly more won’t usually harm plants. However, there’s no need to go overboard. Using huge amounts won’t “super-charge” growth beyond a point; plants can only use so many nutrients at a time. It’s more efficient to apply modest amounts periodically (see the next question on frequency). In summary, aim for those guideline rates (a cup per cubic foot in soil, a tablespoon or two per plant for top-dressing, etc.) and adjust as needed by observing your plants. If they look healthy and green, you’re using enough. If they start looking pale or growth slows, you can increase the dosage or frequency a bit. Experience will guide you, but the suggested amounts above are a great starting point for most situations​.

4. How often should I apply frass to my plants?

As a general guideline, every 2 to 4 weeks during the active growing season is a common frequency for applying mealworm frass. Many gardeners will top-dress or feed with frass about once a month, while heavy-feeding plants might get it biweekly. Frass releases nutrients slowly, so it doesn’t need to be applied as often as a fast chemical fertilizer, but periodic reapplication ensures a continuous supply of nutrients and microbes​.

The optimal frequency can depend on the plant’s needs and how you applied the frass initially:

• If you mixed frass into the soil at planting time, that incorporated frass can feed the plant for several weeks. In that case, you might not need to top-dress with frass until maybe 4-6 weeks after planting. Once the initial nutrients are used up, you can start a routine of adding more.

• A common recommendation is to begin frass top-dressing or teas a couple of weeks after planting and then continue every two weeks or so. For example, one guide suggests starting in week 2 of growth and then reapplying every 2 weeks thereafter​. This frequent light feeding works well because frass is gentle and supports continuous growth.

   

• For less demanding plants or well-established perennials, a monthly application might be sufficient. You could, say, top-dress your flower beds with frass at the beginning of each month through the growing season. Because frass improves soil health as well, you might find that over time you can apply even less often since the soil retains fertility better.

• Pay attention to the growth stage: during peak growth or blooming/fruiting, plants benefit from steady nutrients, so more frequent feeding (every 2 weeks) can maximize yields. During slower growth periods or dormancy, you would stop or greatly reduce feeding. For example, you wouldn’t keep applying frass every month to outdoor plants in winter when nothing is actively growing (except maybe to prep the soil).

• Your specific soil condition matters too. If your soil is very poor or sandy (lacking nutrients), you might lean towards the more frequent side (biweekly) to gradually build it up. If your soil is rich with organic matter, you might only top up occasionally with frass.

In practical terms, many gardeners report that feeding with frass every 3-4 weeks works well for a variety of vegetables and flowers – essentially an application at key stages (like one when seedlings are established, one at flowering time, one mid-fruit, etc.). Others who really push for maximum growth might do smaller applications every 1-2 weeks for heavy feeders like giant sunflowers or prize pumpkins. Since frass doesn't burn, this flexible timing is possible.

Remember that frass not only provides nutrients but also adds microbes and organic matter, whose benefits (like improved soil structure or pest resistance) accrue over time. So regular applications (little and often) can keep boosting those biological benefits. One source notes that you can top dress with frass “every few weeks throughout the growing season” for continued benefits​.

Signs to reapply: If you notice plant growth slowing, leaves yellowing (especially older leaves – could indicate nitrogen is running low), or if it’s been a few weeks since the last feeding, it’s a good time to add more frass. Because it releases slowly, you don’t get the dramatic immediate surge like a liquid fertilizer, but conversely, the effects of one application last longer. So think of frass like a slow-release food – you replenish it periodically to maintain steady nutrition.

In summary, feed most plants with frass about once a month, and consider upping that to biweekly for very fast-growing or nutrient-hungry plants. You can mark your calendar or just observe your garden and feed as needed. With experience, you’ll find the sweet spot, but the 2-4 week interval is a reliable rule of thumb​.

5. Can mealworm frass be used for hydroponics?

Yes, you can use mealworm frass in hydroponic systems, but you’ll need to make some adjustments. Because hydroponics relies on liquid nutrients, you can’t just dump solid frass into your setup without preparation. The common approach is to brew a frass “tea” or solution by mixing frass with water, letting it steep, and then straining out any solids. The filtered liquid can then be added to your hydroponic reservoir or used in a drip system. Frass is at least partly water-soluble and contains organic nutrients that hydroponic plants can use, as well as beneficial microbes. Just be careful to filter it well (to avoid clogging pumps or emitters) and monitor your system, since organic solutions can encourage microbial growth in reservoirs​.

Using organic fertilizers in hydroponics is a bit different from using the typical synthetic hydroponic nutrient solutions, but it can be done. Mealworm frass essentially can serve as an organic nutrient concentrate. Here’s how to make it work:

• Making a frass solution: Take the desired amount of frass and mix it thoroughly into water. For hydroponics, people have found success with ratios like 2 cups of frass per 30 gallons of water​, but you can adjust depending on how nutrient-rich you want the solution. It’s often good to start weaker and see how the plants respond. Stir the frass into the water and let it sit for a while (anywhere from 30 minutes to a few hours). During this time, nutrients like nitrate, ammonium, and soluble phosphorus, as well as organic compounds, will dissolve into the water.

   

• Straining: Before adding this mixture to your hydroponic system, strain it through a fine mesh or cloth. This step is crucial because frass contains fine particles that you don’t want floating around in your pumps or drippers. A double layer of cheesecloth, a fine sieve, or even a coffee filter can work (though coffee filters might be slow; a paint strainer bag is a good option for larger volumes). The goal is a relatively clear (though likely tea-colored) liquid. The strained-out solids (which are basically the remaining insect droppings and bits of organic matter) can be tossed into your compost or garden.

• Using the liquid: The liquid you obtained can now be added to your hydroponic reservoir just like any other nutrient solution. If you run a drip irrigation or NFT hydroponic system, make sure the liquid is well-filtered to prevent clogs in narrow tubes. In ebb-and-flow or Kratky systems, it’s a bit more forgiving with particles, but you still don’t want sediment buildup. You might pour the frass tea through a final fine filter as you add it to the reservoir. Some growers will actually bubble the frass tea with an air stone for 24 hours (like you would with an aerated compost tea) to increase the microbial activity, then strain and use it – but keep in mind a highly biologically active solution can also cause more biofilm in your hydro system.

• Nutrient completeness: Pure mealworm frass tea might not have the perfectly balanced N-P-K and micronutrient profile that commercial hydroponic solutions have, but it can come close. Frass does contain micronutrients and organic acids as well. You may want to monitor your plants for any signs of deficiencies (like if you see a particular micronutrient lacking, you might supplement). However, studies have shown frass can be quite effective even compared to standard fertilizers​. It’s a good idea to check the EC (electrical conductivity) of your frass solution if you have a meter, to gauge its strength, and adjust concentration as needed for your crop.

   

• System maintenance: When running organic nutrients like frass in hydroponics, be aware that the organic matter can encourage growth of bacteria or fungi in the reservoir. This isn’t necessarily bad (some people run fully organic hydro or aquaponics successfully), but you’ll want to keep an eye on any slime or film in your tanks or lines. Using an air pump to oxygenate the solution can help keep microbes beneficial (aerobic) rather than harmful anaerobes. Also, you might need to clean the reservoir a bit more often. On the plus side, those microbes from the frass may actually form a beneficial biofilm that helps roots absorb nutrients or fend off pathogens.

• Application frequency in hydro: In a circulating system, the frass tea will slowly be taken up by plants and microbes. You might need to replenish the nutrient solution more frequently since organic solutions can change over time. Some growers will dose their hydro system with frass tea, then after a week or two, flush and refresh it to avoid any imbalances or buildup.

Overall, mealworm frass can be used in hydroponics as a nutrient source – effectively acting as an organic hydroponic nutrient. Just remember to dissolve and strain. In fact, one product notes that its frass is water-soluble and can be used in hydroponic and fertigation systems. And guidelines recommend straining for drip systems and even mention adding frass tea directly to reservoirs for ebb-and-flow setups​. By following these practices, you can successfully grow hydroponic plants with an organic approach, giving them the benefits of frass’s nutrients and microbes even without soil.