Greenhouse cabinet setup, in the order you should buy it
Most cabinet parts lists are a shopping cart. This one is a sequence, because two of the six items should not be bought until you have measured what the cabinet does on its own. A sealed glass box with plants in it is already more humid than the room around it, and the most common way to overspend on a build is to buy the humidifier at the same time as the cabinet.
Enter your cabinet and it works out the volume, the light each planted shelf needs, and what the whole thing adds to your electricity bill.
The build, in three stages
18.9 cubic feet, 9.9 sq ft of planted shelf, 72.9 kWh a month. About $148.72 a year.
No room reading entered. Measure before buying a humidifier: the cabinet alone raises humidity, and you may need less machine than you think.
Stage 1: Buy first, and stop
- The cabinet · RequiredShrinks the volume so humidity is achievable at all.
- Hygrometer · RequiredTells you what the enclosure does on its own. Buy this before anything that corrects the reading.
Stage 2: Buy after the cabinet is standing
- Grow light, one per planted shelf · RequiredA glass box is darker than it looks, and each shelf shades the one below it.
- Small fan · RequiredHigh humidity with still air is what gray mold wants. NC State treats circulation as the thing that makes the humidity safe.
- Timer or smart plug · RecommendedKeeps the light inside the 16 hour ceiling without you remembering.
Stage 3: Buy only if the reading says so
- Humidifier · Decide after measuringOnly if the week of measurement shows a gap the enclosure did not close.
Light to look for
50 to 66 W per shelf for 3.3 sq ft, aiming at the actually grow level. Across 3 shelves that is 150 to 198 W. Scaled from UMN’s per-plant figures by area, which is our extrapolation rather than their recommendation.
This plan does not size a humidifier, because no extension source maps cabinet volume to required output and a formula for it would be invented. The staging is the answer instead: measure, then buy to the gap. Running cost is arithmetic and assumes the lights at the low end of the range plus a 20 W fan running continuously. The fan is listed as required at every size on the authority of NC State Extension on gray mold, and the full article covers what each part is for.
Why the humidifier is stage three
The honest reason is that nobody publishes the number that would let a tool size one. There is no extension figure mapping cabinet volume to required humidifier output, and a formula invented for the purpose would look authoritative and mean nothing.
What is supportable is the order of operations. Put the cabinet up, put a hygrometer inside, close the doors, and read it after a week. That week costs nothing, risks nothing, and answers a question worth $40 to $150. Many builds turn out to need a fan and patience rather than a machine.
Why the fan is not optional
A cabinet exists to hold humidity. Still, humid air is also the condition that gray mold prefers, so the enclosure that solves one problem creates another unless air is moving. NC State Extension puts it directly: adequate air circulation, even when humidity is high, can greatly reduce the development of gray mold.
That is why the fan sits in stage two alongside the light rather than in a list of optional extras, and it is covered with the sources in the IKEA greenhouse cabinet.
What this planner does not know
It carries verified dimensions for MILSBO, RUDSTA (both sizes IKEA sells it in), and FABRIKÖR, checked directly at ikea.com/us. DETOLF is left out on purpose: its US product page redirects to the general storage category rather than showing a price, which is IKEA’s own signal that it is not currently sold new in the US. If you have a DETOLF already, or found one secondhand, pick “Something else” and measure it, the same as any cabinet not on this list.
The wattage range is University of Minnesota’s per-plant figure scaled by shelf area, which is our extrapolation rather than their recommendation, and the same basis as the grow light calculator. The running cost is arithmetic and exact if your inputs are.
It also does not price the build. Cabinet and component prices move, and a number typed here in September would be quietly wrong by February.
Common questions
- What do I need for a greenhouse cabinet setup?
- Six things, and they are not bought at the same time. The cabinet and a hygrometer come first, on their own. A grow light for each planted shelf and a small fan come second. A humidifier comes last, and only if a week of readings shows the enclosure did not close the gap by itself. A timer or smart plug is strongly recommended for the light.
- Do I need a fan in a plant cabinet?
- Yes, at every configuration. NC State Extension notes that adequate air circulation, even when humidity is high, can greatly reduce the development of gray mold. A closed cabinet is built to hold humidity, and still humid air is the condition fungal disease wants, so the fan is what makes the humidity safe rather than an upgrade. Source: NC State Extension, Botrytis blight of greenhouse ornamentals.
- How big a humidifier do I need for a plant cabinet?
- This planner will not tell you, and no extension source publishes a figure that maps cabinet volume to required output. What is supportable is the sequence: run the closed cabinet with a hygrometer inside for a week first. A sealed glass box with plants in it is already more humid than the room, and many builds need less machine than expected or none at all.
- How much does a greenhouse cabinet cost to run?
- Less than the build cost by a wide margin. The formula is watts times hours per day times 30, divided by 1,000, times your electricity rate. For a typical three-shelf cabinet running lights 13 hours a day plus a small fan continuously, it usually lands in the low single digits of dollars per month.
- How many grow lights does a cabinet need?
- One per planted shelf. A glass cabinet is darker than it looks, and each shelf shades the one beneath it, so a single light at the top leaves the lower shelves below the level anything will grow at.
- Which IKEA cabinet is best for plants?
- It depends on whether you want height or footprint. MILSBO ($279.99, 28 3/4 x 16 1/2 x 68 7/8 in) is the tallest and the one most build guides are written around. RUDSTA comes in two sizes: a tall narrow one ($149.99, 16 1/2 x 14 5/8 x 61 in) and a short wide one ($179.99, 31 1/2 x 14 5/8 x 47 1/4 in), and the short wide version has fewer stacked shelves to shade each other. FABRIKÖR ($179.99, 22 1/2 x 18 1/2 x 59 in) sits in between. DETOLF, the cabinet older build guides default to, is not currently sold new on the US IKEA site: its product page redirects to the general storage category, so treat any DETOLF price you see as a secondhand or resale price, not a current retail one.
Next
The full argument for and against building one, including when not to, is in the IKEA greenhouse cabinet. For the humidifier decision once you have a reading, see humidifiers for houseplants and how to increase humidity. For the plants that make a cabinet worth it in the first place, calathea brown edges explains the 60 percent problem.