Quick Answer: Microgreens want cool air (16-21 C) and deliberately low humidity (50-70%), because damp air brings damping-off. An insulated container is the vertical-farm shell, and often a smarter buy than a turnkey growtainer. You supply the racks, LEDs, and dehumidifier; we supply the box. Delivered across Ontario in just 1-3 days.
In This Guide
Reading Time: 9 minutes
The Shell Versus the Turnkey Box
Container microgreen farms are not a new idea; a handful of companies sell fully built, high-priced turnkey growtainers with the racks, lights, and controls already installed. For some operators that is the right buy. For many Ontario growers, especially a first vertical farm or a market gardener adding a winter crop, it is far more container than budget, and the honest alternative is to buy the insulated shell and fit it out yourself.
The mushroom fruiting room is the mirror image of this build, wet in every place this one stays dry.
That is where a straight container supplier fits. A microgreen room is not a complex climate: it wants moderate cool temperature, deliberately low humidity, and a lot of timed light. None of that requires a five-figure prefit. It requires a well-insulated, sealed, wipe-down box and the grower’s own racks, LEDs, and a dehumidifier. We sell the box honestly and leave the fit-out where it belongs, with the grower who knows their crop.
What Microgreens Actually Need
The controlled-environment figures from Virginia Tech and Penn State are precise, and they are what the room has to hold.
| Parameter | What the CEA guidance specifies |
|---|---|
| Air temperature | 16-21 C (60-70 F); germination soil 15-24 C |
| Relative humidity | 50-70 percent, kept deliberately low |
| Light intensity | Around 250 umol/m2/s PPFD, roughly 70-300 by crop |
| Daily light integral | 9-16 mol/m2/day; a low-light crop, DLI under 20 |
| Photoperiod | 14-18 hours per day of timed LED light |
| Seed to harvest | About 6-10 days for radish, 8-14 for kale, up to ~23 for beet |
The nutrient side is just as defined for hydroponic setups: a solution around EC 1.0, pH 5.5 to 6.0, and roughly 50 to 100 ppm nitrogen, with a standard seeding rate near 10 to 15 grams per standard 10-by-20 tray. These are the grower’s numbers to run; the room’s job is to make holding them easy.
Why Microgreens Want Dry, Not Damp
Here is the point that surprises anyone coming from mushrooms or greenhouse work: microgreens want the air kept dry. The target sits at 50 to 70 percent humidity, and the reason is disease. Excess humidity is what drives damping-off, the Pythium, Botrytis, and Rhizoctonia complex that collapses seedlings at the soil line, and it is the single most common way a microgreen crop fails. High moisture and warm air together are the exact conditions those pathogens favour.
That flips the container recommendation compared to a cheese cave or a mushroom room. The microgreen room’s climate job is moderate cool temperature plus active dehumidification, not refrigeration and not humidification. So the right product is an insulated dry box, not a reefer: the insulation and vapour barrier keep the Ontario weather out, and the grower’s dehumidifier and gentle heat or cool hold the mild, dry band. The mushroom fruiting room is the mirror image of this page, wet where this one is dry, which is exactly why a controllable sealed shell matters for both.
Christian LeBlanc, second-generation operator: “People assume growing means humid. The microgreen folks want the opposite, dry and cool and bright. What they need from us is the plain insulated box, and their money goes into lights and a good dehumidifier, not a fancy pre-build.”
A Timed Light Rack, Not a Window
Microgreens are grown on light, not daylight. The crop wants a daily light integral of 9 to 16 mol per square metre, delivered by LED racks at roughly 250 umol PPFD on a 14-to-18-hour timer. That is a windowless, controllable environment by design, which is another argument for the container: a sealed steel box has a default light level of zero, so the grower builds exactly the photoperiod they want with no sunlight to fight and no seasonal daylight swing to correct for. Racks stack vertically, the timer runs the cycle, and January grows the same crop as June. The vertical stack is where the container earns its keep on yield: a 40ft floor is modest, but four or five rack tiers multiply the growing area far past the footprint, so a small box out-produces a much larger single-level greenhouse bench through the dark Ontario months.
The Cold-Hold That Pays for Itself
One honest upsell worth naming, because it is real value rather than a box we are trying to sell up. Harvested microgreens last only about 2 to 4 days at ambient temperature but 10 to 14 days at 5 C. A grower who adds a small cold-hold zone, or who chooses a reefer specifically so the same unit can grow and then chill, roughly triples the shelf life and the sales window on every tray cut. For a market gardener delivering to restaurants and farmers’ markets, that shelf-life jump is often the difference between selling the crop and composting it. Most growers run an insulated grow box plus a small separate cold space; a few consolidate into a reefer. We will lay out both honestly against your sales pattern.
The Vertical-Farm Shell, Priced Straight
Tell us your tray volume and your postal code. We will spec the insulated shell and be clear about the lights, racks, and dehumidifier that stay yours, in a same-day quote.
What We Supply and What Stays Yours
The honest line: we provide the insulated, sealable shell and the electrical- and ventilation-ready envelope. We do not supply lights, racks, dehumidifiers, nutrients, or growing know-how, and we make no yield or food-safety guarantee. Every setpoint on this page belongs to Virginia Tech and Penn State, not to us. Selling microgreens for people to eat is a food business under CFIA and OMAFRA produce-safety rules, and that compliance is the grower’s. A container is the room; the grower owns the biology, the sanitation, and the CEA equipment.
The shell reaches you in one to three days, which for a grower usually means racks in before the next seeding., and if you are weighing a bare shell against a turnkey growtainer or a built room, the hub that compares a container to the alternatives gives you the honest frame. Worth seeing the envelope before the rest of the budget goes on lights.
Frequently Asked Questions
What temperature and humidity do microgreens need?
Air around 16 to 21 C (60 to 70 F) with humidity kept deliberately low at 50 to 70 percent. The low humidity matters: damp air drives damping-off disease, the most common way a microgreen crop collapses. It is the opposite of a humid grow room.
Do I need a reefer or a dry container for microgreens?
An insulated dry box is usually right. Microgreens want moderate cool temperature and active dehumidification, not refrigeration or added humidity. A reefer is worth it only if you also want the same unit to cold-hold harvested trays, which extends shelf life considerably.
How much light do microgreens need in a container?
A daily light integral of 9 to 16 mol per square metre, delivered by LED racks at roughly 250 umol PPFD on a 14-to-18-hour timer. A windowless container is ideal because you build the exact photoperiod with no sunlight to fight and no seasonal daylight swing.
Is a bare container cheaper than a turnkey growtainer?
Usually, yes, often by a wide margin. Turnkey growtainers arrive with racks, lights, and controls pre-installed at a premium. A microgreen room is a simple climate, so many growers buy the insulated shell and fit their own racks, LEDs, and dehumidifier for far less.
How long do harvested microgreens last?
About 2 to 4 days at room temperature but 10 to 14 days at 5 C. That is why some growers add a cold-hold zone or choose a reefer, roughly tripling shelf life and the sales window, which for restaurant and market sales often decides whether the crop sells or spoils.
Sources
- Virginia Cooperative Extension. Microgreens (SPES-756). pubs.ext.vt.edu
- Penn State Extension. Microgreens production. extension.psu.edu
- Ontario Ministry of Agriculture, Food and Agribusiness. Produce safety and specialty-crop resources. ontario.ca
- Canadian Food Inspection Agency. Safe Food for Canadians: fresh fruits and vegetables. inspection.canada.ca
- International Organization for Standardization. (2020). ISO 668, Series 1 freight containers. iso.org
Reach Van Blanc in Brantford
We have supplied and converted insulated containers across Ontario since 1995. Bring your tray volume and your fit-out plan, and we will talk shell, insulation, and the honest split on what you build versus what we deliver.
Van Blanc Ent. Inc., 90 Morton Ave E Unit 1B, Brantford, ON N3R 7J7. +1 888-509-6658
It is worth seeing the shell before you spend the rest of the budget on lights and a dehumidifier.