Grow smarter at every stage
Choose a goal, get the right tool, and keep your grow moving.
Week 4 · Vegetative
Example- Temp
- 24.6°C
- RH
- 62%
- VPD
- 1.21 kPa
- PPFD
- 520
Grow progress
Royal Strain Finder
Find the best strains for your goals
Strain Finder Quiz
Answer six questions, get a ranked shortlist
Compare Strains
Put your finalists head to head
What can we help you with today?
Pick the goal closest to your situation and we'll point you at the right tool.
How the tools work together
Use the right tool at each stage and carry what you learn into the next.
- 1
Choose
Find and compare strains that suit the grow you can actually run.
- 2
Plan
Estimate the yield your space can give, and build the feed schedule around it.
- 3
Grow
Hold the climate, feed to the stage, and name problems early when they appear.
- 4
Harvest & improve
Score the finished grow, read back what moved the result, and carry it into the next one.
Explore each tool in detail
See what it does, what you'll need, and what you'll get.
Describe what you want in plain English and get five strains that fit.
Best for
- Narrowing 2,000+ strains to a shortlist
- Knowing the outcome you want, not the strain
What you'll provide
- What you want, in plain English
What you'll get
- 5 strains with match scores
- The drawbacks and the reasoning for each
Tell it what you want in plain English and it picks 5 strains from 2,000+ with match scores, drawbacks, and reasons. The flagship tool — predictive, honest, and sharper with every session.
Answer six questions and get every strain ranked by fit.
Best for
- A fast shortlist
- A ranking you can repeat and check
What you'll provide
- Answers to 6 questions
What you'll get
- All 2,000+ strains ranked by fit
- A deterministic result, no free-text nuance
The classic 6-step weighted-scoring quiz. Pure algorithm — answer 6 questions and get a deterministic ranking of all 2,000+ strains by fit. Faster than Royal Strain Finder, without the free-text nuance.
Put up to four strains side by side and break the tie.
Best for
- Two or three finalists you cannot choose between
What you'll provide
- Up to 4 strains
What you'll get
- THC, CBD and effects side by side
- Terpenes, difficulty, yield and price
Stack up to 4 strains side-by-side across THC, CBD, effects, terpenes, difficulty, yield, and price. Useful when you have 2-3 finalists and need to break the tie.
The preferences behind your picks, gathered in one place.
Best for
- Working out what you actually like
What you'll provide
- Nothing — it builds from your sessions and grows
What you'll get
- Top terpenes and strain-type lean
- Ideal THC range and archetype name
- Liked and excluded strains
Your accumulated preferences — top terpenes, strain-type lean, ideal THC range, archetype name, liked and excluded strains. Built from your Royal Strain Finder sessions and grow outcomes.
Estimate your harvest weight before the seeds go in.
Best for
- Setting expectations before a grow starts
What you'll provide
- Strain and environment
- Tent size and light wattage
- Grow technique
What you'll get
- An estimated harvest weight
Estimate harvest weight from strain, environment, tent size, light wattage, and grow technique. Tells you what to expect before you germinate.
Build a per-stage feeding schedule for your medium and nutrient brand.
Best for
- Avoiding burn, lockout and deficiency
What you'll provide
- Grow medium (soil / coco / hydro)
- Nutrient brand
- Plant count
What you'll get
- A per-stage feeding schedule
Per-stage nutrient feeding schedule based on grow medium (soil / coco / hydro), nutrient brand, and plant count. Avoid burn, lockout, and deficiency.
Upload a plant photo and get a clear diagnosis and recovery plan.
Best for
- Deficiencies, pests, mould and watering issues
- Light stress and pH lockout
What you'll provide
- 1–3 clear photos
- Optional grow details
What you'll get
- Likely cause with a confidence score
- Prioritised fix steps
- Recovery timeline and nutrient advice
Your photo is saved to your session so you can ask follow-up questions about it.
Upload a photo of a sick plant and get a diagnosis with confidence score, severity, fix steps, recovery timeline, and nutrient recommendations. Covers deficiencies, pests, water issues, light stress, pH lockout, and mould. Includes a follow-up chat for plant-specific questions.
Hit your target VPD with a specific temperature and humidity change.
Best for
- Temperature, humidity and VPD
- Rooms that drift out of range
What you'll provide
- Current temperature and humidity
- Your grow stage
What you'll get
- Target VPD and how far off you are
- Three adjustment paths via Fix-My-Room
- Risk warnings and strain recommendations
Interactive VPD calculator with sliders, a circular meter, dynamic chart, and stage-specific climate recipes. Tells you how much to adjust temp and humidity to hit your target VPD. Includes Fix-My-Room with three adjustment paths, risk warnings, and strain recommendations tuned to your environment.
Stage-aware EC and pH targets, adjusted for your climate.
Best for
- Overfeed, underfeed and pH lockout
- Salt buildup from runoff EC drift
What you'll provide
- Your grow stage and nutrient line
- Runoff EC, if you measure it
What you'll get
- EC and pH targets
- Watering volume, frequency and dry-back
- Product recommendations per nutrient line
Stage-aware EC and pH targets, watering volume and frequency, dry-back guidance, and climate-adjusted dosing. Detects salt buildup from runoff EC drift, warns on overfeed, underfeed, and pH lockout, and recommends products per nutrient line. Save each feed to your Grow Journal.
Track each grow from germination through to harvest.
Best for
- Keeping the whole history of one grow in one place
What you'll provide
- Your strain and stage updates
- Final outcomes at harvest
What you'll get
- Stage-specific advice for your strain
- Captured yield, quality and rating
- Data that sharpens future recommendations
Track each grow from germination to harvest. Get stage-specific advice tailored to your strain, capture real outcomes (yield, quality, rating), and feed that data back into future recommendations.
Reads your whole journal and surfaces what changed before symptoms did.
Best for
- Connecting climate, feeding and symptoms
What you'll provide
- An active grow with logged readings
What you'll get
- A weekly grow report
- What changed before symptoms appeared
- Magnesium demand and salt buildup forecasts
Reads your VPD readings, feedings, diagnoses, and stage history together. Generates a weekly grow report, surfaces what changed before symptoms appeared, forecasts magnesium demand and salt buildup, and answers grow questions with full context.
Log the finished grow and find out what actually worked.
Best for
- Closing the loop on a completed grow
What you'll provide
- Final yield and bud quality
- Smoke profile and difficulty
What you'll get
- A 100-point Harvest IQ Score
- Yield measured against strain expectation
- What worked, what hurt, and what to grow next
Closes the grow loop. Log final yield, bud quality, smoke profile, and difficulty. Get a 100-point Harvest IQ Score, yield analysis against strain expectation, what-worked and what-hurt reasoning from your journal, next-strain recommendations, and a shareable Harvest Replay link.
Lab results, grower reports and terpene data in one reference.
Best for
- Growers who want the numbers, not the marketing
What you'll provide
- Nothing — browse freely
What you'll get
- Aggregate lab results
- Grower reports and terpene data
- Category breakdowns
Aggregate lab results, grower reports, terpene data, and category breakdowns. The reference hub for growers who want the numbers, not the marketing.
Every feminized and autoflower seed we carry, filterable.
Best for
- Browsing without a shortlist in mind
What you'll provide
- Nothing — browse freely
What you'll get
- The full Royal King Seeds catalogue
- Filters for category, strain type and THC range
Browse the full Royal King Seeds catalogue of feminized and autoflower cannabis seeds. Filter by category, strain type, or THC range.
Turn a year of growing into something you can share.
Best for
- Sharing your year with other growers
What you'll provide
- Nothing — built from your sessions and grows
What you'll get
- Archetype and top terpene with effect blurb
- Ideal THC range, best grow, total sessions
- A public link and a preview image
Your year-end recap — archetype, top terpene with effect blurb, ideal THC range, best grow, total sessions. Shareable with a public link and a dynamic preview image.
Compare tools by stage
Compare every tool by purpose, time required, and account access.
Times are estimates for a first run. “Sign in” means the tool keeps a record against your account.
See what the tools actually tell you
Not a description of the output — the output.
You enter
82°F air · 45% RH
leaf -2°F · early flower
Your VPD
1.82 kPa
Outside the range for this stage
Target for early flower
1.10 – 1.30 kPa
Ideal 1.20 kPa
What it tells you to change
At 82°F, hold humidity between 59–64% (ideal 62%). Or leave humidity at 45% and bring air temperature to 67–72°F.
- Raise humidity — add humidifier output, mist walls, or wet towel over passive intake
- Lower air temp by 2-3°F to reduce the air’s moisture demand
- Reduce exhaust fan speed (don’t pull moisture out as aggressively)
Worked from one sample reading using the same VPD formula and stage targets the tool itself uses. Your own numbers will differ — that is the point of running it.
Transparent calculations
For the calculated tools you can see the inputs, the stage target, and the gap between them — not just an answer. The VPD engine uses the Magnus-Tetens equation against a published per-stage range.
Your grow data
A photo you upload is kept with your session so the follow-up chat can still refer to the plant. Journal entries are tied to your account and are read back only for that account.
Read the privacy policyBuilt for every stage
Targets move with the plant. Climate and feed guidance changes between seedling, veg and flower, and the journal keeps separate timelines for autoflowering and photoperiod plants.
Try one right here
Live — the real Climate Coach engineMove the sliders. This is the same calculation the Climate Coach runs, not a picture of one.
Leaf temperature is assumed 2°F below air, the usual figure under LED. The full tool lets you set it.
Your VPD
1.26kPa
In range
Target for this stage: 1.20–1.50 kPa
Hold it here. At 78°F that means keeping humidity near 52%.
You’re inside the ideal range for this stage — just monitor and hold
Open Climate CoachPractical guidance, with the reasoning shown
The tools combine the grow details you provide with growth-stage targets, environmental calculations and Royal King strain information. Where we can show the inputs and the reasoning behind a recommendation, we do — so you can judge it rather than take it on faith.
Calculated
Repeatable. You can check the working.Climate Coach · Yield Calculator · Nutrient Calculator · Strain Finder Quiz
Fixed formulas over the numbers you enter. The Climate Coach computes vapour pressure deficit with the Magnus-Tetens equation and compares it to a target range held for each growth stage; the calculators and the quiz score your inputs the same way every time. Enter the same figures tomorrow and you get the same answer.
Interpreted
Judgement, not arithmetic. Treat it as a second opinion.Strain Finder · Plant Doctor · Feed Coach · Grow Copilot · Harvest IQ
These read what you give them — a description, a photo, a run of journal entries — against our catalogue and strain data, and write back a reading of it. Because they are interpreting rather than solving, two runs on the same input can phrase things differently or weigh a detail differently.
Understand the limitations
Calculator output is an estimate
A yield figure is a projection from the numbers you entered, not a promise. Real harvests move with genetics, technique, light, and everything that happens over sixteen weeks.
Two growers can get different results from the same advice
The same VPD target behaves differently in a sealed room and a tent in a garage. Phenotype varies inside a single strain. The guidance is a starting point for your conditions, not a constant.
Trust the plant over the number
If a reading says the room is fine and the plant plainly is not, believe the plant. Sensors sit in one spot, canopies do not, and a photo cannot see root zone or runoff. Go and look before you chase a decimal place.
A photo cannot see everything
Plant Doctor works from what is visible in the frame. Root problems, pests on the underside of leaves, and anything already corrected before the photo will not be in the picture, so its confidence score is about the image, not the plant.
The cultivation reference behind these tools lives in our grow guides, where the reasoning is written out at length.
Questions about our tools
For seeds, shipping and germination, see the main FAQ.
Are the grower tools free?
Yes. Every tool on this page is free to use, and none of them asks for payment details.
Do I need an account?
For most of them, no — 11 of the 15 run without one. An account is needed only where a tool has to keep a record between visits: the Grow Journal, Grow Copilot and Harvest IQ read your saved grows, so they need to know whose grows they are. The comparison above marks which is which.
How accurate are the results?
It depends on the tool. The Climate Coach and the calculators are arithmetic — the same inputs always produce the same answer, and you can check the working. The interpretive tools give a reading of what you describe or photograph, so treat those as a second opinion rather than a verdict. Either way the output is only as good as what you enter: a sensor in the wrong spot produces confident nonsense.
Are uploaded plant photos private?
Your photo is stored against your session so the follow-up chat can still refer to the plant you showed it — without that, the conversation loses the thing it is discussing after the first reply. It is not shown to other growers. See our privacy policy, and contact support@royalkingseeds.com about anything you have uploaded.
Can I use the tools for autoflowers?
Yes. The Grow Journal keeps separate stage lengths for autoflowering and photoperiod plants, so its timeline and harvest estimate follow the right schedule for the plant you are actually running. Climate and feed targets are driven by growth stage, which applies to both.
Can I save or export my results?
Results are saved wherever a tool writes to your Grow Journal, which you can read back from My Grows at any time. There is no file export yet.
Coming soon to Royal Grower Tools
Currently in development. Join the list to hear when they launch.
Planting calendar
Sowing and harvest windows worked back from your season and setup, so an outdoor grow starts on a date that suits it.
Build your own pack
Assemble a mixed pack from the strains you shortlisted, instead of choosing between fixed combinations.
Stage reminders
A nudge when a grow reaches the point where something usually needs changing — a flip, a feed change, a last watering.