Independent lab · est. 2026
Shady Knoll Labs builds sensors, software, and plain-spoken data for people who grow plants, and for anyone who wants to know what their plants are actually getting.
Project 01
Small, inexpensive sensors that read the light (PPFD and far-red), temperature, and humidity where your plants actually sit, paired with a dashboard that turns raw readings into something you can act on.
Visit gnodehub.comLight alone doesn’t grow a plant. PPFD tells you how much usable light is landing on a leaf. VPD tells you whether the air around that leaf will actually let it use the light it’s getting. GNode Hub measures both.
PPFD · measured by the light sensor
Photosynthetic Photon Flux Density is a count — how many particles of light a plant can actually photosynthesize with land on a square meter of leaf every second (µmol/m²/s). It isn’t the same as “brightness” the way a lux meter reads a room: a dim-looking corner under a full-spectrum grow light can carry more usable PPFD than a sunny windowsill. That’s the number in the meter above.
VPD · calculated from temperature & humidity
Vapor Pressure Deficit is the gap between how much moisture the air is holding and how much it could hold at that temperature. Too small a gap and a plant barely transpires — nutrient uptake stalls and mold risk climbs. Too large, and it loses water faster than its roots can replace it. Try the sliders:
Simplified estimate — assumes leaf temperature equals air temperature.
Readings are only useful if you can trust them. We document how a number was produced and where it stops being reliable.
You shouldn't need a lab coat to understand your own windowsill. The tools are built for hobbyists first.
The long-term plan is for this work to be self-hostable by the maker community, not locked behind a subscription.