Grow-Kashi: a live bokashi soil conditioner with fermented biochar and mycorrhizal fungi
Grow-Kashi is a live bokashi soil conditioner: seven inputs fermented together, sprinkled on the soil surface to put bacteria, fungi and microbial food back into a growing medium. Organic fertiliser only feeds a plant once soil organisms have broken it down, and fresh potting mix or tired, re-used container soil often has very few of them. Dr Forest makes every batch fresh to order in Stockport and vacuum-seals it, because the organisms are alive and their numbers fall once the seal is broken.
The seven inputs are EM bokashi bran, fermented biochar, diastatic malted barley, organic Indian neem meal, Scottish seaweed, humic and fulvic acid, and a mycorrhizal inoculant. It is not an NPK feed; use it alongside a granular organic fertiliser such as All Purpose 4-4-4. Sold in 250 g and 1 kg pouches.
What is bokashi for plants used for?
- Inoculating new potting mix — bagged peat-free composts are often biologically sparse; a top-dressing at potting gives the pot a working community from day one
- Reviving re-used container soil — a season of cropping runs down microbial diversity; a surface application and a few days' rest before replanting brings it back
- Getting more out of organic dry fertilisers — pellets and meals need soil organisms to mineralise them before the plant gets anything
- Establishing mycorrhizal fungi — the inoculant colonises roots within a week or two and extends their reach for water and phosphorus
- Living soil and no-dig beds — re-inoculate at the start of each crop cycle; the biochar stays put between cycles as a permanent microbial habitat
- Heavily cropped outdoor beds — a light monthly sprinkling on beds that see intensive fertiliser inputs or back-to-back crops
Why a live fermented conditioner rather than a dried inoculant powder?
Grow-Kashi — live, fermented, fresh to order
- Organisms arrive active on a fermented substrate they have already colonised, with malt sugars to feed on as they establish
- Biochar carries the community into the soil and stays there for decades as habitat
- A white bloom on the surface within 2–7 days shows you it is working
- The trade-off is shelf life: 3 months unopened, 6 weeks once open
Shelf-stable dried inoculant powder
- Spores and dormant cells that have to wake up before they do anything
- No food source or habitat in the packet; the organisms are on their own once applied
- Viable counts fall with age and warm storage, and you cannot see whether it has taken
- Keeps for a year or more in the cupboard, which is its one real advantage
Grow-Kashi is fermented and vacuum-packed in small batches at the Dr Forest workshop in Stockport, Greater Manchester, made with organic ingredients and sent out fresh rather than held in stock. If you are new to fermented soil inputs, start with how to use bokashi bran in your soil. Made by Growers. Backed by Science.
The science of Grow-Kashi: what each of the seven inputs does
Why a soil conditioner instead of more fertiliser
Plants take up nitrogen, phosphorus and the rest as simple ions. Organic fertiliser has to be mineralised into that form first, and bacteria and fungi do the work. Fresh bagged compost, last year's pot soil and beds fed for years with soluble feed can all be short of those organisms, so the fertiliser you add sits there. Grow-Kashi puts them back, with food and habitat so they stay. The wider argument is in what is living soil?
Two of the seven inputs bring organisms (EM bokashi bran, mycorrhizal inoculant). Two bring habitat and carbon (fermented biochar, humic acid). The rest bring food, enzymes and growth signals. The whole mix is fermented together before packing.
No analysis figures are given because Grow-Kashi is not sold as a nutrient source. At 1–3 ml per litre of soil the nitrogen and potassium from the neem meal and seaweed are negligible. Feed separately.
Mechanisms of action
EM bokashi bran: the fermentation culture
EM was developed by Teruo Higa at the University of the Ryukyus as a mixed culture of mutually compatible organisms, mainly lactic acid bacteria and yeasts with smaller numbers of photosynthetic bacteria (Higa and Parr, 1994). Grow-Kashi uses bran inoculated with that culture as the starter for the whole ferment. One caveat: in a four-year Swiss field trial, living EM performed no differently from sterilised EM, and the small gains seen came from the bokashi substrate rather than the organisms (Mayer et al., 2010, Applied Soil Ecology). That is why Grow-Kashi does not rely on the EM culture alone.
Fermented biochar: habitat that stays
Biochar is porous, carbon-stable and persists in soil for decades. A review of the literature found that microbial biomass typically increases when biochar is added, with shifts in community make-up and enzyme activity (Lehmann et al., 2011, Soil Biology and Biochemistry). In Grow-Kashi the biochar is slow-fermented with volcanic rock dust, diastatic malted barley, worm castings, humic acid and a compost extract carrying mycorrhizal fungi before packing, so it goes into the pot already colonised.
Diastatic malted barley: enzymes and first food
Diastatic malt is barley germinated and dried at low temperature so its enzymes survive. Amylase, protease and phosphatase start breaking starches, proteins and organic phosphorus down as soon as the malt is wetted, and the malt sugars feed the introduced organisms in the first days, which is when the white bloom appears. The same input is sold on its own as organic malted barley.
Neem meal: organic matter that holds nitrogen
Neem meal is what is left of the seed after the oil is pressed out. It is in the blend as organic matter and slow nitrogen, and because compounds in neem seed slow the conversion of ammonium to nitrate. In a compost-amended sandy soil, neem seed gave around 40% nitrification inhibition lasting 40 days and roughly 60% less nitrate leached (Abeka et al., 2022, Frontiers in Soil Science). That was a tropical soil at field rates, so treat the numbers as indicative.
Scottish seaweed: growth signals and trace elements
Whole seaweed extracts upregulate the plant's own auxin, cytokinin and gibberellin synthesis, increase seedling root size and density, and change the microbial make-up of soil and plant (Ali et al., 2021, Plants). The same review notes that fractionating the extract into single components does not reproduce the effect. Grow-Kashi uses whole Scottish Ascophyllum nodosum for that reason.
Humic and fulvic acid: chelation and root growth
A meta-analysis put the mean response to humic substances at 22% more shoot dry weight and 21% more root dry weight, with the shoot response larger under stress, 28% against 18% (Rose et al., 2014, Advances in Agronomy). Humic acid adds cation exchange sites that hold calcium, magnesium and potassium against leaching; fulvic acid is the smaller fraction and chelates trace elements into forms roots take up. Both are covered in humic vs fulvic acid.
Mycorrhizal fungi: a second root system
Arbuscular mycorrhizal fungi grow into root cells and send hyphae out into soil the roots cannot reach, trading phosphorus and water for plant sugars. Across 187 studies, inoculation raised whole-plant biomass by 47%, nitrogen uptake by 67% and phosphorus uptake by 105%, with larger effects in laboratory experiments than in the field (Wu et al., 2024, BMC Plant Biology). Container growing is where root volume is most limited, so it is also where this matters most. See what are mycorrhizal fungi?
What the evidence does and does not say
The inputs are individually well studied. Grow-Kashi as a finished blend has not been through a replicated trial, and the EM literature is mixed. What you can rely on is the visible bloom within a week, the biochar staying in the soil, and the published responses to humic substances and mycorrhizal inoculation. Do not expect a fertiliser effect; if a plant is hungry, feed it.
Scientific references
- Higa, T. and Parr, J.F. (1994). Beneficial and Effective Microorganisms for a Sustainable Agriculture and Environment. International Nature Farming Research Center, Atami, Japan.
- Mayer, J., Scheid, S., Widmer, F., Fliessbach, A. and Oberholzer, H.-R. (2010). How effective are 'Effective microorganisms (EM)'? Results from a field study in temperate climate. Applied Soil Ecology, 46(2), 230–239.
- Lehmann, J., Rillig, M.C., Thies, J., Masiello, C.A., Hockaday, W.C. and Crowley, D. (2011). Biochar effects on soil biota: a review. Soil Biology and Biochemistry, 43(9), 1812–1836.
- Abeka, H., Lawson, I.Y.D., Nartey, E., Adjadeh, T., Asuming-Brempong, S., Bindraban, P. and Atakora, W.K. (2022). Effectiveness of neem materials and biochar as nitrification inhibitors in reducing nitrate leaching in a compost-amended Ferric Luvisol. Frontiers in Soil Science, 2, 1023743.
- Ali, O., Ramsubhag, A. and Jayaraman, J. (2021). Biostimulant properties of seaweed extracts in plants: implications towards sustainable crop production. Plants, 10(3), 531.
- Rose, M.T., Patti, A.F., Little, K.R., Brown, A.L., Jackson, W.R. and Cavagnaro, T.R. (2014). A meta-analysis and review of plant-growth response to humic substances: practical implications for agriculture. Advances in Agronomy, 124, 37–89.
- Wu, Y., Chen, C. and Wang, G. (2024). Inoculation with arbuscular mycorrhizal fungi improves plant biomass and nitrogen and phosphorus nutrients: a meta-analysis. BMC Plant Biology, 24, 960.
How to use Grow-Kashi: application, storage and what to expect
Grow-Kashi is made fresh to order and contains living bacteria and fungi. Use within 6 weeks of opening the vacuum-sealed bag, and within 3 months of purchase. When storing, minimise exposure to oxygen: keep in a sealed container out of direct sunlight. The organisms are alive and active; their numbers decline over time once the seal is broken. Treat this product like a fresh food item, not a shelf-stable dry fertiliser. As a measure, 1–3 ml is approximately ¼–½ teaspoon.
Sprinkle Grow-Kashi evenly over the soil surface after watering, not before. The moist soil surface provides the ideal environment for the organisms to migrate downward into the root zone. Do not bury or mix in: surface application is the correct method. The organisms will colonise the growing medium naturally from the surface.
Application rates
Standard application: all plants, containers and beds
Use the lower rate (1 ml/L) for regular maintenance and the higher rate (3 ml/L) for new or biologically depleted soil.
New potting soil or growing medium
Fresh potting mixes are often biologically sparse. Apply the higher rate at first potting to establish the microbial community from the outset. Follow with regular maintenance applications every 4–6 weeks to sustain the biology. This is particularly important for peat-free media, which typically contain very little native biology.
Re-used or tired container soil
Soil that has been cropped through a full season has depleted its microbial diversity. Before re-planting, apply the full rate of Grow-Kashi to the surface, water gently, and allow 3–5 days for the biology to establish before transplanting. Continue with regular fortnightly or monthly applications throughout the growing season.
Long-term pots and containers
Growing media kept in the same pot for a long time are especially prone to biological decline. Regular low-rate applications of Grow-Kashi maintain a healthy microbiome in the pot, and the musty odour associated with biologically dead soil tends to fade with it. Apply after watering and leave undisturbed.
Living soil and no-dig (no-till) systems
Grow-Kashi is a natural fit for living soil and no-dig growing. Apply at the start of each crop cycle to re-inoculate the microbial community after harvest. The fermented biochar provides a permanent microbial habitat that persists between cycles, building cumulative biological diversity with each application.
Outdoor beds, vegetable plots and flower borders
Scatter a thin, even layer across the soil surface of outdoor beds after watering or rainfall. Outdoor soils typically have more native biology than container media, so lower rates and less frequent application are usually sufficient. Focus applications on beds that have been heavily cropped or that receive intensive fertiliser inputs.
What to expect after application
- White bacterial bloom on the soil surface. Within 2–7 days of application, you will very likely see a white, fuzzy growth appearing on the soil surface. This is a bacterial bloom, a visible sign that the introduced organisms are colonising the growing medium. It is natural, harmless to your plants, and indicates that the product is working. Do not remove it. It will subside on its own as the microbial community establishes equilibrium.
- Improved nutrient uptake from organic fertilisers. If you are using organic dry fertilisers (like Dr Forest All Purpose 4-4-4 or Bloom 2-8-4), you may notice faster and more complete nutrient release after Grow-Kashi inoculation. The organisms you have introduced are the workforce that mineralises organic nutrients into plant-available forms.
- Healthier root development over time. The mycorrhizal fungi will begin colonising plant roots within 1–2 weeks. The visible effect, stronger and more resilient plants with better drought tolerance, develops over successive weeks as the fungal network extends through the growing medium.
Grow-Kashi is the biological complement to all Dr Forest fertilisers. Use alongside All Purpose 4-4-4 or Bloom 2-8-4 granular feeds: the Grow-Kashi provides the organisms that break down the organic nutrients, and the fertiliser provides the nutrients those organisms mineralise. For liquid feeding, the biology from Grow-Kashi supports Liquid Fertiliser 5-2-5 and Liquid Fertiliser 3-2-6 by maintaining healthy root-zone conditions. Combine with slow release humic acid for soil CEC building and microbial habitat support, and with unsulphured molasses as a follow-on food for the organisms.
After opening, transfer any unused Grow-Kashi to a sealed container and store in a cool place out of direct sunlight. Minimise exposure to oxygen: the organisms are facultative anaerobes that remain most stable in low-oxygen conditions. Use within 6 weeks of opening for best results. The vacuum-sealed bag preserves viability for up to 3 months from purchase. Do not refrigerate or freeze.
