STEP 01
SYMPTOM · OBSERVED
Blossom-end rot
Dark, sunken lesion at the fruit base, logged from the plant journal.
01WHY A GRAPH
Your plant’s problem isn’t what it looks like.
Take blossom-end rot in tomato: dark sunken patches at the base of the fruit, the textbook sign of calcium deficiency. So you reach for the cal-mag. Meridian traces the symptom back through the graph instead, and lands at the real root of the issue.
EVIDENCE PATH · BLOSSOM-END ROTclick any step for its source
STEP 02
MECHANISM
Calcium isn’t reaching the fruit
Saure 2001, calcium moves with transpiration flow, not toward the low-transpiring fruit.
STEP 03
ROOT CAUSE · LIVE SENSOR
Reservoir pH 5.4
Below the 5.8 to 6.3 window where roots can take up Ca²⁺. Reading straight off the reservoir probe.
SOURCELive reservoir probe, last read 2 minutes ago. The 5.8 to 6.3 band is the documented uptake window for calcium.
STEP 04
ACTION
Raise pH to 6.3
Restores uptake of the calcium already in solution, no extra feed needed.
DEAD ENDAdd calciumThe reservoir already holds plenty. More calcium changes nothing while the pH keeps the roots from taking it up.
Don’t add calcium. Fix the pH.
02WHAT MERIDIAN DOES
Every plant, watched five ways.
The journal, the assistant, your own hardware, the precision tools, and the verified reference all read the same live state. This is what they add up to.
Plant journal
Every reading, photo, and note lands on one timeline. The plant’s whole history, not your memory of it.
Meridian AI
Ask in plain language. It answers from your plant’s live state and the graph behind it, with the path it took.
Your hardware
Reads the sensors and controllers you already run. AC Infinity, Aranet, SwitchBot, no rip-and-replace.
Precision tools
VPD, PPFD, pH, and nutrient math, calibrated to your tent and your fixture, not a generic chart.
Verified reference
A hand-curated atlas of plant cause and effect, drawn from university research, not forum lore.
LIVE·/APP DASHBOARD
Good morning, grower
DAY 36 · 1 ACTIVE PLANT · TENT A
PLANTOPEN →
Plant 1
DAY 36 · VEGETATIVE
CANOPY SCORE+3 VS YDAY
84OF 100
ENV92SUB71IRR84LIGHT95CAM90
7-DAY86 · 79
Meridian narrative07:42
Zone time held overnight.
Zone time finished at 88.9% with a couple of short drifts around midday. Substrate moisture is easing toward the floor of its band and the reservoir is down to 32%, so a top-up lands in the next couple of days.
Open zone detail →Top up reservoir 32%
IN ZONE16h 00m/ 18h88.9%
06:0012:0018:0000:0006:00
In zoneDriftingOut of zoneLights off
ENV · VPDIn zone
1.18kPa
TARGET 0.8-1.4 kPa
SUB · MOISTUREDrifting
53%
TARGET 55-70%
IRR · RESERVOIRTop up
32%
5 GAL CADENCE
TASKS
Top up reservoir soon
Reservoir is at 32%. A 5 gal top-up holds about 6 more days.
JOURNAL
Raised reservoir pH to 6.1
Today 08:14 · manual entry
03THE TOOLKIT
Twelve calculators. One you can try right now.
Try the PPFD coverage map live below, or open any other tool from the list.
Most advanced
Nutrient Calculator
Our most advanced tool. Models the full nutrient solution, ion interactions and antagonisms, with stage-by-stage PPM and EC targets, grounded in peer-reviewed plant-nutrition science.
Open the nutrient calculator →VPD CalculatorVapor pressure deficit targetDLI CalculatorDaily light integral totalLight Sizing CalculatorFixture wattage and heightCO₂ CalculatorEnrichment, duration, and costDehumidifier SizingRight dehumidifier capacityEC/PPM ConverterEC, PPM, and TDS scalespH CalculatorpH up and down dosesNutrient Schedule BuilderWeekly nutrient targetsReservoir CalculatorDilution and volume mathSubstrate Volume CalculatorContainer volume and bagsPPFD MapLIVECanopy coverage heatmap · try it on the right →
LIVE·INTERACTIVE PPFD MAPOpen the full tool →
Light coverage, before you hang a thing.
Hover the canopy to read a point.
0900+ µmol·m⁻²·s⁻¹
YOUR TARGET RANGE 300 to 600 µmol · drag the handles to set your own.
AVG PPFD
582µmol
UNIFORMITY
0.44
IN TARGET BAND
47%
MIN / MAX
256 / 890µmol
DLI
37.7mol·d⁻¹
COVERAGE
16.0ft² of 16
SPACE
FIXTURES + LAYOUT
FIXTURE TYPE
TARGET STAGE
Hot center, dim edges. Raise the fixture, add one, or turn on walls.
Inverse-square × cos²θ superposition model, the same physics as the /tools PPFD Map. A model, not a measured IES file or a substitute for a quantum meter.
04METHODOLOGY
You can check the work.
The graph is not scraped and it is not generated. Every relationship is sourced, reviewed by a horticulturist, and typed before it joins the atlas. The path Meridian walks is the citation.
How an edge is built
1
Source
peer-reviewed + bulletins
2
Review
horticulturist sign-off
3
Edge
typed, directed relationship
4
Published
into the live atlas
5
Maintained
audited and re-verified
100%
EDGES REVIEWED
0
AUTO-GENERATED
Sources behind one edgeBER → CALCIUM TRANSPORT FAILURE
2005
Ho, L.C. & White, P.J.. A cellular hypothesis for the induction of blossom-end rot in tomato fruit.
Annals of Botany 95(4)
2001
Saure, M.C.. Blossom-end rot of tomato, a calcium- or a stress-related disorder?
Scientia Horticulturae 90(3-4)
1993
Adams, P. & Ho, L.C.. Effects of environment on the uptake and distribution of calcium in tomato.
Plant and Soil 154
1993
Ho, L.C., Belda, R., Brown, M., Andrews, J. & Adams, P.. Uptake and transport of calcium and the possible causes of blossom-end rot in tomato.
J. Experimental Botany 44
2009
Hochmuth, G.J. & Hochmuth, R.C.. Blossom-End Rot in Bell Pepper: Causes and Prevention.
UF/IFAS EDIS SS497
05THE ATLAS
The graph does not stop at one plant.
410,480
Plant species mapped in the living atlas
Each one becomes a dense web of cause and effect, the same structure that takes a symptom back to its cause. We start where the data is deepest and grow outward, one verified relationship at a time.
Stop guessing in your grow space.
Connect the hardware you already run and let the graph trace the next problem back to its cause.