Free tools
Free garden calculators
& tools.
Zone finder
Enter a US ZIP or UK postcode — get your USDA zone or RHS rating, frost dates, and what to plant this week.
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Frost-date calculator
Get your average last spring frost, first fall frost, growing-season length, and crops to sow after frost.
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Watering frequency calculator
Pick plant, pot size, light, and season — get the suggested watering interval across 25+ species.
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Pot size calculator
Enter your current pot and time since repot — get a repot verdict, next pot size, and soil mix.
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Plant spacing calculator
Pick a crop and bed size — get plant and row spacing, total plants that fit, and the square-foot alternative.
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Soil pH guide
Pick a plant — get its ideal pH range, how to test soil, and the exact amendments to raise or lower pH.
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Light meter guide
Answer three quick window questions — get an estimated lux range and plants that thrive at that light, no meter needed.
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Companion plant finder
Pick a crop — get the top companions and antagonists with the evidence strength behind each pairing.
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Frost dates by USDA zone
Browse the average last and first frost for all 13 USDA zones, plus tender crops to sow after frost.
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Want all of this in one place, personalized?
These calculators give quick one-off answers. The Growli app remembers your specific plants, tracks your local weather, and tells you what to do each day — watering reminders, frost alerts, and repot timing tuned to your garden.