GROWER ECONOMICS · INPUT COST
What microgreen substrate really costs per tray, once yield and labor are in the number. Fix it from only $3 a month.
Growers price this input by the sack and then wonder where the money went. The sack price is the smallest part of it. Here is what each substrate actually costs a tray once you count the harvest it returns, the minutes it adds at the sink, the freight it arrives on, the floor it occupies and the bill to make it disappear again.
The input everyone underprices, and always in the same direction
Ask a grower what their substrate costs and you get the price of the sack divided by the number of trays it filled. That is an honest answer to the wrong question. It treats the substrate as a thing you buy rather than as a thing that determines what you have to sell at the end of the week.
The gap between a quality compost based mix and a cheap generic bag off a hardware shelf ran roughly 25 percent in harvest weight across the varieties we grew. Put that against a 100 tray a week operation grossing $4,000 a month and the gap is about $1,000 a month. No sack price anywhere in this category moves $1,000 a month. The purchase decision is worth pennies. The consequence of the purchase decision is worth four figures.
So the useful comparison is never $0.75 against $0.50. It is what a tray of each returns, what each one costs you to handle, and what each one costs to get rid of.
What each option costs to buy
Input cost per 10 by 20 tray, with the yield index from our own trials at microGREEN FX indexed to the compost based peat-free mix at 100. Shelf life is refrigerated, across sunflower, pea, radish, broccoli and salad mix.
| Substrate | Input cost per tray | Yield index | Shelf life | Where it pays |
|---|---|---|---|---|
| Compost based peat-free mix | $0.75 to $1.60 | 100 | 10 to 14 days | Retail and CSA, where weight is revenue |
| Coconut coir | $0.40 to $1.20 | 85 to 90 | 8 to 12 days | Restaurant bagged supply |
| Hemp fiber | $0.50 to $1.20 | 80 to 85 | 7 to 10 days | Grocery and bulk packed |
| Jute or burlap fiber | $0.30 to $0.80 | 75 to 85 | 7 to 10 days | Hobby scale, too variable to commit to |
| Peat based mix | $0.50 to $1.40 | 95 to 100 | 10 to 14 days | Declining, on buyer preference not agronomy |
Cost per tray is the wrong number. Cost per unit sold is the right one.
Take the cheapest line and the dearest. Jute at $0.30, compost based mix at $1.60. The difference is $1.30, and $1.30 a tray is genuinely worth having if nothing else changes.
Something else changes. Apply the yield index and the jute tray comes off the rack with a fifth to a quarter less product in it. It fills a fifth to a quarter fewer clamshells. On any tray whose finished product is worth several dollars, a fifth of the harvest is worth considerably more than $1.30, and the cheap option turns out to be the expensive one by a comfortable margin.
That arithmetic only flips when harvest weight is not your constraint. If you are already growing more than you can sell, the scarce thing is rack space and your own time, not weight, and buying yield you cannot move is buying compost. Which is the real question underneath this whole comparison. Are you short of product, or short of buyers? A grower with a waiting list should optimise for weight. A grower with unsold stock should optimise for time.
The labor minute at the sink
A compost based mix leaves fine grit on the cut stems, and the answer is a quick rinse at harvest that adds about thirty seconds a tray. Thirty seconds reads as nothing. Run it out.
At 100 trays a week that is fifty minutes a week, which is a bit over 43 hours across a year. Price your own hour honestly. At $20 an hour it is under $900 a year of your time, spent to protect a yield advantage worth more than that at the same volume. The trade holds, but only just, and it stops holding if you value your hour higher or if your volume is lower.
Fiber options hand those minutes straight back. That is the entire labor case for them and it is a real one. It is also the case that gets ignored, because the minutes never arrive as an invoice. Nobody bills you for the extra fifty minutes. They just come out of the end of your Saturday.
One more labor line that goes uncounted: variability. Jute and burlap shift batch to batch in thickness and absorbency, and every batch that behaves differently costs a round of adjustment. We ran both for a quarter and stopped, not on price and not on weight, but because inconsistency is a recurring cost that never shows up in a column anywhere.
Reuse, and the bill at the far end
Spent substrate can go around once more. Cut the root mat up, work it back through, and the second cycle returns roughly 60 to 70 percent of the first. After two cycles it is depleted, loaded with root debris and carrying real disease pressure. At that point it goes on the compost heap.
Whether reuse is worth doing is a straightforward comparison and it usually loses. You are spending labor minutes to recover a fraction of a dollar of input, while accepting a risk that is priced in whole trays rather than in cents. One lost tray erases a season of the saving.
Disposal is the line nobody costs at all, and it is the one that varies most by where you grow. A grower with a heap and a wheelbarrow pays nothing and gains a soil amendment. A grower in a leased unit in town pays a hauler, usually by weight, and a compost based substrate weighs several times what the same number of spent fiber sheets weigh. Before you conclude that any option is cheap, find out what it costs you to make it go away. Fiber is the light choice at both ends of its life, and in a rented unit that can decide the whole question.
Freight and floor space
The delivered price is not the shelf price. Bagged compost based substrate is dense, freight is priced by weight, and a pallet of it costs meaningfully more to move than the equivalent number of fiber sheets or compressed coir bricks. That is precisely why coir is shipped compressed. It is the cheapest way to move a growing medium across an ocean, and the saving reaches you as a lower delivered price.
Storage is the same argument indoors. A month of substrate for a 100 tray week is a real footprint in a small unit, and floor space in a leased space has a rent attached to it whether you count it or not. Compressed bricks occupy a fraction of the space of the loose bagged equivalent.
Bulk buying cuts the input cost, and bulk pricing on a compost based mix runs $0.50 to $0.80 a quart against retail bag pricing. The payback is real but it arrives slowly, and it arrives as cash tied up and floor you no longer have. A bulk order that outlives its own shelf life or gets in the way of the rack has not saved anybody anything.
I spent six months buying every option I could find and comparing them. The brand differences inside a category were smaller than I expected. The category differences were exactly what microGREEN FX had already published. Pick the category, pick a supplier who is boring and consistent, and stop paying yourself to second-guess it.
Microgreen grower, Vermont
Which channel pays for which substrate
No buyer pays a premium for the medium itself. Nobody at a market stall has ever paid extra because you grew on coir. What the substrate changes is how much product you have to sell and what it cost you to get it into the pack. So match it to the channel, not to the photograph on the package.
- Farmers market retail. Weight is revenue and flavor closes the sale. Compost based peat-free mix, and absorb the rinse.
- Restaurant wholesale. Depends entirely on packaging. Bulk bagged deliveries reward the cleaner coir product. Clamshells get rinsed anyway, so take the yield instead.
- Grocery wholesale. Shelf life is the constraint and the customer buys with no sample, so presentation is doing the selling. Fiber or coir, and accept the weight gap as the cost of entry.
- CSA shares. Educated buyers who care about flavor more than visual perfection and will rebag happily. Maximize weight.
Notice that three of the four answers are downstream of packaging rather than of growing. That is usually the tell that you are looking at a business decision wearing an agronomy costume.
The peat question, priced honestly
Peat costs about the same and returns about the same. So this is not a cost decision at all. It is a market access decision, and it should be argued on those terms rather than on yield.
The UK, Ireland and several EU countries have brought in partial or full restrictions on horticultural peat, and North America is drifting the same way. Large retailers and grocery chains now ask organic suppliers about peat-free practices as part of sustainability reviews. That is the money side of it: a buyer requirement you cannot satisfy is a channel you cannot enter, and being ready for it costs nothing today because the yields are equivalent.
At microGREEN FX I stopped buying a mix in early 2022 and started making my own from scratch instead: compost based, with no peat moss in it. We call it MicroThrive Soil. Flavor, nutrients and longevity were the design brief, and I want to be straight that this is what I built it for rather than a lab result I am reporting to you. Yield stayed identical to the peat based mix it replaced. That was my call for my farm. Most bagged microgreen mixes on the shelf are still peat based, plenty of good growers use them and produce excellent trays, and if that is you then nothing about your operation is wrong.
How to decide, without spending a season on it
Do not switch on a spreadsheet and do not switch on a forum thread. Run four trays of the candidate against four trays of your current substrate, same variety, same week, same rack. Weigh both. Treat anything under 90 percent of your control as a no, and treat anything over it as worth a second run before you commit a pallet.
The reason to bother is that the ranking is genuinely operation-specific. Your room, your water, your varieties and your buyers are not mine. What holds everywhere is the shape of the answer: input cost is a rounding error, yield and labor are not, and disposal decides it for anyone paying rent.
Where the app fits
Every tray you log in Grown Like A Pro carries the substrate it grew in, the weight it produced and the price it sold at. The analytics then rank your options by dollars per square foot for your operation rather than for mine, which is the only ranking that pays. Most growers who run this for a quarter find their instinct was wrong on at least one variety.
Basic analytics and CSV export start on Solo at $3.00 a month. Grower at $12.99 adds 30 questions a day with Glappy, the assistant that will read a photo of a tray and name the likely cause, and Pro at $19.99 raises that to 100 a day. The $0 plan carries 8 active trays, unlimited microgreen varieties and the full cheat sheet, which is enough to run the four tray comparison above without paying anything.
GLAP is on Google Play for Android and runs in any browser. The iOS build is in App Store review.
Rank your substrates by dollars per square foot →Already bought the bag and need to get it into a tray properly? Follow the ten step bench procedure for filling and pre-moistening a 10 by 20 tray → It covers screening, the squeeze test, fill depth, levelling, firming and how a fiber mat changes the sequence.
Frequently asked questions
What does growing substrate cost per tray?
Between roughly $0.30 and $1.60 for a standard 10 by 20 tray, depending on the option. Jute and burlap are the cheapest at $0.30 to $0.80, coconut coir runs $0.40 to $1.20, hemp $0.50 to $1.20, peat based mixes $0.50 to $1.40, and a quality compost based peat-free mix $0.75 to $1.60. That spread is small enough that it should not decide anything on its own. Seed and labor are both larger lines, and the harvest weight each option returns is larger still.
Which substrate is cheapest once yield is counted?
The compost based peat-free mix, in most operations, despite being the dearest to buy. Indexing yield at 100 for that mix, coir returns 85 to 90, hemp 80 to 85 and jute or burlap 75 to 85. Giving up a fifth of the harvest weight costs far more than the $1.30 a tray you saved at purchase. The exception is a grower who cannot sell everything already grown, because then weight is not the constraint and paying for yield you will not move is pointless.
Does a soilless option save enough labor to pay for itself?
Sometimes, and it depends on your volume and what you value an hour at. A compost based mix adds about thirty seconds a tray at harvest for a rinse, which is fifty minutes a week at 100 trays and a bit over 43 hours a year. At $20 an hour that is under $900 of your time, against a yield advantage worth more than that at the same volume. Lower your volume or raise your hourly rate and the trade reverses, which is why the answer is genuinely different for a weekend grower and a full time one.
Is reusing spent substrate worth the saving?
Rarely. A second cycle returns roughly 60 to 70 percent of the first, and after two cycles the material is depleted, full of root debris and carrying disease pressure, so it belongs on the compost heap. You are spending labor minutes to recover a fraction of a dollar of input while taking on a risk priced in whole trays. A single lost tray wipes out a season of the saving, which is why most growers who try reuse quietly stop.
What does it cost to get rid of spent substrate?
Anything from nothing to a real monthly line, and it depends entirely on your site. With a heap and a wheelbarrow it is free and it comes back as a soil amendment. In a leased unit in town you pay a hauler, usually by weight, and a compost based substrate weighs several times what the equivalent spent fiber weighs. Growers renting space regularly find disposal decides the question for them, which is the one input cost almost nobody checks before buying.
Does the substrate I grow on earn a price premium?
No. No buyer has ever paid more because of the medium in the tray. What the medium changes is how much product you have to sell and what it cost you to get it packed. Peat-free is the partial exception, and even then the value is access rather than price: some retailers and grocery chains now ask organic suppliers about peat-free practices, so it can open a channel rather than raise what that channel pays you.
Is peat cheaper than peat-free?
No, and it does not yield more either. Peat based mixes run $0.50 to $1.40 a tray against $0.75 to $1.60 for compost based peat-free, and the harvest weights are equivalent. So peat is not a cost argument. It is a market access argument. The UK, Ireland and several EU countries have restricted horticultural peat, North America is drifting the same way, and large buyers are starting to ask. Moving is cheap precisely because nothing about the yield changes.
How do I decide whether to switch at all?
Run four trays of the candidate against four trays of your current option in the same week, on the same rack, with the same variety, and weigh both. Anything under 90 percent of your control is a no. Anything above it earns a second run before you commit to a pallet. The ranking is operation-specific, because your room, water, varieties and buyers are not somebody else's, and a spreadsheet built on another farm's numbers will confidently tell you the wrong thing.
The bottom line
Stop shopping for the cheapest sack. The purchase price of a growing medium sits between $0.30 and $1.60 a tray, and no decision worth making lives inside a $1.30 spread. The money is in the harvest weight the medium returns, the minutes it costs you at the sink, the freight and floor it occupies and the bill to remove it.
Work it in cost per unit sold. Let your channel and your site break the tie: weight for retail and CSA, cleanliness and shelf life for grocery, disposal weight if you are paying rent. Then leave it alone and let your technique improve against a fixed variable, because half the arguments about substrate online are two growers comparing their own inconsistency.