Published experiments show that vermicompost can improve plant growth under some conditions. The useful question is what was tested, against which control, and for how long. Here are two studies to read with their methods in view.
A tomato-seedling study with a comparison photo
In 2022, Raman Tikoria, Arvinder Kaur and Puja Ohri studied tomato seedlings exposed to root-knot nematodes. Their vermicompost came from neem leaves and cow manure. Seeds also received vermicompost-extract pretreatments, before seedlings entered the different growing mixtures.
After ten days of infection, Table 1 reports mean shoot lengths of 9.77 cm for infected seedlings without vermicompost, 16.43 cm for the 100% treatment, and 13.67 cm for the uninfected control. The photograph illustrates treatments; the measurements support the comparison. This short experiment combined growing-medium and seed treatments and did not establish fruit yield. The paper does not state the experimental sample size. Read the complete study and methods.
Another tomato study: soil and the comparison matter
In 2015, Marc Zucco and colleagues ran two greenhouse experiments with three soil textures, four replicates, and seven treatments. They compared no amendment, a standard inorganic fertilizer, and five vermicompost rates. Growth measurements were taken two months after transplanting.
The higher vermicompost rates generally improved several growth measurements over the untreated control, while many results were similar to the standard fertilizer treatment. Lower rates did not improve every measurement. Soil texture also affected growth. These results concern this material and experiment; they do not turn its tested rates into a recipe for every garden. Read Zucco et al., “Effect of soil type and vermicompost applications on tomato growth” (2015).
How to read growth photos and results
Keep the treatment labels attached to a research photo. Then check the crop, growing medium, other inputs, timing and control. Ask whether the result measures seedling size, dry biomass or harvested yield. Those measurements answer different questions.
Both papers studied materials and conditions different from Soily's blend; neither tested our product. Their percentages are experimental treatments, not Soily application directions. A photograph also cannot predict how your plants will respond. Use research to ask better questions about a material and your own growing conditions.
For the terminology behind these studies, read our worm castings and compost guide. To choose a base growing medium first, see compost, topsoil or potting mix.