How to Use Mealworm Frass Fertiliser on Plants

Mealworm frass is easy to use: sprinkle it onto the soil, lightly mix it into the surface, then water it in. You do not need complicated equipment or a long preparation process.

This guide covers a simple starting point for using RichRoots mealworm frass in pots, veggie gardens, raised beds and new plantings.

Quick guide: how much frass should I use?

Where you're using it	Starting amount
Small pots (10–15cm)	1–2 teaspoons
Medium pots (20–25cm)	About 1 tablespoon
Large pots (30cm+)	1–2 tablespoons
Garden beds	Sprinkle lightly and evenly around the root zone
New planting	Mix a small amount through the planting area

After applying, lightly work the frass into the top layer of soil where practical and water as normal.

These are practical starting rates rather than rigid rules. Plant size, pot size, season and soil condition all affect how much fertiliser a plant needs.

How often should I apply mealworm frass?

For actively growing plants, a useful starting point is approximately every 2–4 weeks.

You may use less during slower growth or cooler periods. For seedlings, newly established plants or plants that are already stressed, start lightly and see how the plant responds before increasing the amount.

Using frass in pots

1. Measure a small amount based on the pot size above.
2. Sprinkle it across the soil surface rather than piling it against the stem.
3. Lightly mix it into the top layer of potting mix if practical.
4. Water the pot normally.

For indoor plants, using a measured amount is particularly helpful because the soil volume is limited and it is easy to add more fertiliser than the plant needs.

Using frass in garden beds and veggie patches

Scatter a light, even layer around the plants you want to feed, concentrating on the soil around the root zone. Lightly work it into the surface and water it in.

You do not need to cover every centimetre of the bed with a thick layer. Regular, modest applications are a better starting point than assuming more will produce a better result.

Using frass when planting

When putting in a new plant, mix a small amount of frass through the surrounding soil rather than placing a concentrated pocket directly against delicate roots or stems. Plant as usual and water in well.

Do I need to compost RichRoots frass first?

For the soil and pot applications described in this guide, RichRoots is supplied for direct use. Follow the modest rates above and start lightly around seedlings and sensitive plants.

What is in RichRoots mealworm frass?

RichRoots is 100% raw mealworm frass. Our current independent analysis found:

Parameter	Result
Nitrogen (N)	3.71%
Phosphorus (P)	1.13%
Potassium (K)	1.88%
Carbon	38.5%
Magnesium	0.66%
Sulfur	0.25%
Calcium	0.19%
pH	6.0

It also contains naturally occurring trace elements. Because frass is a natural product, nutrient levels can vary somewhat between batches.

Why use mealworm frass?

Mealworm frass provides plant nutrients and carbon-rich organic matter in a compact form. It also naturally contains chitin. Research on mealworm frass is still developing, so we prefer not to treat every laboratory or greenhouse finding as a guaranteed result in every home garden.

For everyday use, the practical reason to choose it is simpler: it is an easy-to-apply soil amendment and fertiliser that can be incorporated into a normal feeding routine for pots and garden beds.

What about frass tea, foliar sprays or hydroponics?

Some growers experiment with liquid extracts and specialised growing systems, but those applications require different considerations from ordinary soil use. This guide therefore focuses on the method we can recommend most simply for home gardeners: apply the frass to soil and water it in.

If you are using a hydroponic, fertigation or foliar system, do not assume the dry application rates above translate directly to that system.

How much do I need?

For most home gardens, the 360g Large Garden Pouch is the better-value size for repeated feeding across several plants, veggie beds or larger pots.

As a rough guide, when feeding every two weeks for about 12 weeks, one 360g pouch can cover approximately:

• 12–15 small pots (10–15cm)
• 3–5 medium pots (20–25cm)
• 2–3 large pots (30cm+)

If you only have a few pots or want to try frass first, the 110g Small Garden Pouch is the smaller-format option.

Shop the 360g Large Garden Pouch →

Want to learn more?

Read our mealworm frass FAQs or explore the science behind frass.

For delivery, packaging and returns information, see our Delivery, Shipping & Returns page.