Houseplants · Containers · Gardens
Elmer’s Gold
Pure worm castings for mixing into potting soil or top-dressing established plants. Our straightforward starting point for everyday gardening.
4 lb and 16 lb
From $16.00
Shop Elmer’s GoldIowa Worm Farm · Family roots. Practical growing.
Worm castings for your plants.
A family you can get to know.
Bring Elmer’s Gold into your houseplant, container, and garden routine. Explore our castings and soil amendments, with clear directions and real people here to help.
Family-produced castingsLab testing & growing trialsPickup in Coralville, Iowa
Choose what fits your growing plans.
Start with the way you garden. Each product has a clear role—and directions to help you use it.
Seed starting
S Brand Sprout Mix
Enriched worm castings to blend into your seed-starting medium. See how it performed alongside plain castings in our growing trial.
4 lb and 16 lb · Mix into growing medium
From $20.00
Shop S Brand
Build your own soil blend
BioBoost Biochar
Plain, unamended biochar for gardeners who want control over their soil blends. Prepare it with finished compost before use.
1.5 lb and 6 lb · Preparation required
From $15.00
Shop BioBoostShipping calculated at checkout. Local pickup available in Coralville by arrangement. Shipping details
Meet the people behind the products
Rooted in family.
Guided by observation.
John produces the castings behind Elmer’s Gold. Adam develops the blends, checks the castings with laboratory testing and microscope observations, and helps customers put them to work.
We share what we learn through practical growing trials and honest conversations about soil.
Read our family’s story →See our seed-starting comparison.
Three approaches to starting tomatoes. At day 46, the plants shown with Elmer’s Gold and S Brand had visibly larger root systems than the starting mix alone. The control received tap water; both amended groups received reverse-osmosis water. See the photo and full comparison.
Explore S Brand and watch the trial →Read our laboratory reports and trial details →
Reports describe the samples tested; natural batches and growing results vary.
From our customers’ gardens.
“I just mix into a chunky soil mix before repotting my plants.”
Read the full review →
“Delivery arrived safely and swiftly”
Questions before you choose?
Tell us what you’re growing. We’ll help you find the right product and understand how to use it.
We stand behind what we sell. Product-price refunds for dissatisfaction, with no return required. Read our satisfaction promise