Best Worm Castings (2026)

Earthworm castings are the gentlest soil amendment you can buy. They will not burn roots, they smell like a forest floor rather than manure, and a little goes a long way: a 10 to 20 percent blend in potting mix, a half-inch top-dressing, or a cup steeped into a bucket of water for a casting tea. The bagged products on Amazon look similar, but they differ in ways that matter: how finely they are screened, how moist they arrive, what the worms were fed, whether the bag is OMRI listed for organic growing, and how much you get per bag. We sorted the current listings by those differences so you can match a bag to the job, whether that is houseplants, a few raised beds or a whole vegetable garden.

Part of our Composting & Soil guide →

In this guide

1. 1. Wiggle Worm Pure Worm Castings 30 lb — Best Overall for Gardens
2. 2. Brut Worm Farms Organic Worm Castings 12 lb — Best Mid-Size Organic Bag
3. 3. Plantonix Worm Bliss 8 Qt — Best for Houseplants
4. 4. VermisTerra Earthworm Castings 10 lb — Best Fine Texture for Top-Dressing
5. 5. Mountain Valley Seed Earth Worm Castings 1 Gallon — Best for Making Worm Tea
6. 6. Back to the Roots Organic Worm Castings 5 lb — Best Small Bag with a Guarantee
7. 7. Wiggle Worm Pure Worm Castings plus Worm Egg Material 40 lb — Best for Building Living Soil
8. What to Look for in Bagged Worm Castings
9. How Much Worm Castings to Use
10. Frequently Asked Questions

Disclosure: Urban Lotus Project earns a commission from qualifying Amazon purchases made through links on this page, at no extra cost to you.

How we compared: we compared 18 current Amazon listings for bagged worm castings on what each listing states, including bag size, organic listings, feedstock and screening. We did not test or handle the products, and availability changes.

Castings are only one part of a healthy soil program; our composting and soil guide covers compost, mulch and testing, and our guide on how to use worm castings goes deeper on rates for each use.

1. Wiggle Worm Pure Worm Castings 30 lb — Best Overall for Gardens

Best overall

Why We Like It

• Large bag covers beds, containers and transplant holes
• OMRI listed for organic gardens
• Listing says pure castings, not leftover bedding
• Clear use directions: a handful at planting

Specification	Details
Bag size	30 lb
Organic listing	OMRI listed
Product type	Pure castings, marketed as a fertilizer
Texture	Small football-shaped particles, per listing
Suggested use	Above the root zone three times a year, or in the planting hole
Feedstock	Not stated in listing

Wiggle Worm Pure Worm Castings 30 lb — compressed specs

Wiggle Worm is the name that shows up most on this shelf, with the 30 lb bag listed under two ASINs and a four-pack of 30 lb bags for larger gardens. The listing draws a clear line between its product and cheaper vermicompost: it says the bag contains pure castings rather than uneaten bedding, and that the product is recognized as a fertilizer because of how it is harvested. It describes the particles as tiny and football-shaped, which helps both aeration in dense soil and water holding in sandy soil.

The use directions are refreshingly modest: a handful or half a cup into the planting hole, or a top-dressing above the root zone three times a year. At 30 lb, that is enough for a season of vegetable transplants, several raised beds and a stack of containers. The one thing the listing does not cover is what the worms are fed, so if you need a manure-free product, look at Plantonix instead.

Check Wiggle Worm Pure Castings 30 lb price on Amazon

2. Brut Worm Farms Organic Worm Castings 12 lb — Best Mid-Size Organic Bag

Best mid-size

Why We Like It

• Both OMRI and CDFA listed
• Worms raised indoors in containers
• Family-owned producer
• Sold in 5, 12 and 30 lb sizes

Specification	Details
Bag size	12 lb (5 lb and 30 lb also listed)
Organic listing	OMRI and CDFA listed
Production	Worms raised indoors in containers
Use	Potting soil and garden soil, indoor and outdoor
Feedstock	Certified organic ingredients, per listing

Brut Worm Farms castings 12 lb — compressed specs

Brut is the only brand on the shelf that lists both OMRI and CDFA (California Department of Food and Agriculture) organic input registration, which matters to gardeners who want a second check on organic status. The listing says the worms are raised indoors in containers and fed certified organic ingredients, which suggests a more controlled product than outdoor windrow castings.

The 12 lb bag sits in the sweet spot for most home gardeners: enough to blend into potting mix for a season of containers and top-dress a couple of raised beds, but light enough to store in a garage or under a potting bench. Brut also offers 5 lb and 30 lb versions on this shelf, so you can scale up once you know you like it. The listing is heavy on marketing language and light on specifics such as screening size or moisture.

Check Brut Worm Castings 12 lb price on Amazon

3. Plantonix Worm Bliss 8 Qt — Best for Houseplants

Best for houseplants

Why We Like It

• Vegan, manure-free feedstock
• Screened to remove dirt, sand and rocks
• Climate-controlled worm facility
• Also comes in a 1 quart bag

Specification	Details
Bag size	8 quarts (1 quart also listed)
Organic listing	OMRI listed
Feedstock	Strictly vegan diet, manure-free
Screening	Screened for dirt, sand and rocks
Use	Potting mixes, containers, indoor and outdoor plants

Plantonix Worm Bliss 8 Qt — compressed specs

If you are working indoors, manure-free feedstock is a reasonable thing to care about, and Plantonix is the clearest listing on that point: worms raised in a climate-controlled facility on a strictly vegan diet, then screened to remove dirt, sand and rocks. That combination makes it the most comfortable choice for blending into houseplant mixes, top-dressing a fiddle-leaf fig or adding to a seed-starting mix at a low rate.

The bag is sold by volume rather than weight, which is honest for a product whose weight swings with moisture. Eight quarts is roughly a quarter of a cubic foot, plenty for a houseplant collection for a year or more. Plantonix lists the same product under two ASINs at 8 quarts and in a 1 quart trial bag, so start small if you only have a few pots.

Check Plantonix Worm Bliss 8 Qt price on Amazon

4. VermisTerra Earthworm Castings 10 lb — Best Fine Texture for Top-Dressing

Best for top-dressing

Why We Like It

• Cured and very fine texture
• Low moisture means more castings per pound
• Spreads evenly on lawns and beds
• Brand also makes a liquid casting tea

Specification	Details
Bag size	10 lb
Texture	Cured, very fine
Moisture	Low, per listing
Odor	No odor; will not burn plants
Organic listing	Not stated in listing
Feedstock	Not stated in listing

VermisTerra Earthworm Castings 10 lb — compressed specs

Moisture is the hidden variable in worm castings. A damp bag weighs more and clumps, so you get fewer actual castings per pound and a harder time spreading them. VermisTerra is the one listing on this shelf that makes low moisture and a cured, very fine texture its selling point, and that suits top-dressing: a fine, dry material sifts down between plants and into turf instead of sitting in lumps.

The listing is short and does not mention an organic certification or feedstock, which is the main trade-off. VermisTerra also has a gallon of liquid earthworm casting tea with kelp on this shelf; that is a separate concentrate rather than castings, so we left it off the picks, but it is an option if you want a ready-made liquid.

Check VermisTerra Castings 10 lb price on Amazon

5. Mountain Valley Seed Earth Worm Castings 1 Gallon — Best for Making Worm Tea

Best for worm tea

Why We Like It

• Includes a recipe for liquid worm tea
• OMRI certified organic
• Neutral pH of about 7.0 stated
• Small bag, roughly one gallon

Specification	Details
Bag size	About 0.13 cu ft, roughly 6 lb or 1 gallon
Organic listing	OMRI certified
Feedstock	Certified organic cow manure processed by red worms
pH	About 7.0, per listing
Extras	Worm tea recipe included

Mountain Valley Seed Earth Worm Castings — compressed specs

Casting tea stretches a small bag a long way, and Mountain Valley is the only listing that ships a tea recipe with the castings. The listing also gives more detail than most: red worms and red wigglers processing certified organic cow manure, OMRI certification, and a neutral pH around 7.0. It pitches the product as a cleaner, nearly odorless alternative to bagged cow manure.

Note the feedstock. If you specifically want manure-free castings for indoor use, Plantonix is the better fit. For outdoor tea, seedlings and container vegetables, this is a well-documented small bag. One gallon will make many batches of tea at a cup or two per 5-gallon bucket.

Check Mountain Valley Castings 1 Gal price on Amazon

6. Back to the Roots Organic Worm Castings 5 lb — Best Small Bag with a Guarantee

Best small bag

Why We Like It

• Made in the USA
• No burn and no odor stated
• Satisfaction guarantee with refund or replacement
• Easy 5 lb size for patios and pots

Specification	Details
Bag size	5 lb
Product type	Vermicompost
Origin	Made in the USA
Use	Vegetables, herbs, flowers and houseplants
Organic listing	Described as organic; certifier not stated in listing

Back to the Roots Organic Worm Castings 5 lb — compressed specs

Back to the Roots is a familiar garden brand, and its 5 lb bag is aimed at the patio and houseplant gardener who wants something they can pour from without a scoop. The listing calls the product US vermicompost, says it contains beneficial microbes, and promises no burn and no odor. The standout is the satisfaction guarantee: if you are unhappy, the company offers a refund or replacement.

Be aware that vermicompost is a slightly broader term than pure castings; it can include partly processed bedding. Wiggle Worm makes a point of that difference. For mixing into potting soil at 10 to 20 percent, either works fine. The listing also does not name an organic certifier, unlike Brut, Wiggle Worm and Plantonix.

Check Back to the Roots Castings 5 lb price on Amazon

7. Wiggle Worm Pure Worm Castings plus Worm Egg Material 40 lb — Best for Building Living Soil

Best for living soil

Why We Like It

• Worm cocoons may hatch in your soil
• Largest single bag on the shelf
• Aimed at boosting microbial activity
• Listing is upfront about possible debris

Specification	Details
Bag size	40 lb
Contents	Pure castings plus worm egg material (cocoons, soil balls, bedding)
Debris	Some small rocks may pass the sifting, per listing
Use	Indoor and outdoor; best suited to beds
Organic listing	Described as organic; certifier not stated in listing

Wiggle Worm Castings plus Worm Egg Material 40 lb — compressed specs

This is a different product from Wiggle Worm’s pure castings. It blends castings with worm egg material: cocoons, tiny soil balls and bits of unfinished bedding. The idea is that some cocoons hatch, and those worms keep working in your beds. The listing is honest that small rocks and debris can make it through the sifting, so this is not the bag for a fine houseplant mix.

Where it fits is in-ground beds and raised beds with plenty of organic matter, where hatchlings have food and moisture to survive. Composting worms such as red wigglers live in rich surface litter rather than deep mineral soil, so expect them to persist mostly under mulch and in compost-heavy beds.

Check Wiggle Worm Castings plus Egg Material price on Amazon

What to Look for in Bagged Worm Castings

Pure Castings vs Vermicompost

Pure castings are mostly worm excrement, screened from the bedding. Vermicompost is the broader output of a worm bin, castings plus partly broken-down bedding and food. Both are useful. Pure castings are finer and more concentrated, which suits potting mixes and tea. Vermicompost is a little coarser and works well as a top-dressing or bed amendment. Our comparison of worm castings vs compost explains where each fits next to regular compost.

Organic Listing and Feedstock

If you grow to organic standards, look for OMRI listing, and CDFA registration if you garden in California. Feedstock varies: some producers use manure, others vegetable waste or grain-based feed. Manure-fed castings are perfectly safe for gardens; vegan feed mainly matters to people working indoors or who prefer it on principle.

Moisture and Texture

Castings should be dark, crumbly and slightly moist, like a wrung-out sponge, never soggy or sour-smelling. Very wet bags clump and can grow surface mold in storage. Fine, screened castings are best for seed starting and houseplants; coarser material is fine outdoors.

Bag Size and Storage

Buy for one season. Castings are most biologically active when fresh, so store the bag closed, out of direct sun and protected from freezing or drying out completely. Rough use guide: a 1 quart to 5 lb bag for houseplants, 10 to 12 lb for containers and a couple of beds, 30 lb or more for a vegetable garden.

How Much Worm Castings to Use

Use	Typical rate
Potting mix	10 to 20 percent by volume (about 1 part castings to 4 to 9 parts mix)
Seed-starting mix	About 10 percent; more can hold too much moisture
Top-dressing containers	1/4 to 1/2 inch layer every 2 to 3 months in the growing season
Transplant holes	A handful to 1/2 cup per plant
Garden beds	About 1/2 inch worked into the top few inches in spring
Casting tea	About 1 to 2 cups per 5 gallons of dechlorinated water, steeped 24 to 48 hours

Castings are gentle, but they are not a complete fertilizer for heavy feeders. Tomatoes, peppers and squash still benefit from a balanced organic fertilizer; think of castings as a soil conditioner and mild nutrient source.