34 gardening calculators
Each one solves a specific gardening problem with ZIP-keyed data, methodology on-page, and provenance to NOAA or USDA.
Pick a category to start — every tool ships with methodology and NOAA/USDA sourcing.
Last Frost Date
Average last spring frost for your ZIP, in 50/30/10% probability bands.
PLNFirst Fall Frost Date
When to expect your first cool night — and your harvest deadline.
PLNSeed Starting Date
When to start vegetable seeds indoors based on last frost + crop.
PLNTransplant Date
When to move seedlings outdoors for optimum survival.
PLNHarvest Date Estimator
Expected harvest window from transplant date + days-to-maturity.
PLNSuccession Planting
Multiple sowing dates for continuous harvest.
PLNDays-to-Plant
Countdown to sow / transplant / harvest events.
PLNSoil pH by Crop
Check whether your soil pH falls inside the optimal band for 27 crops.
SOILSoil Amendment
Lime, gypsum, sulfur dosing plans.
SOILFertilizer NPK
Calc exact nutrient ratios.
SOILMulch Coverage
Cubic yards of mulch needed at any bed size.
SOILCompost Quantity
Yard waste to usable compost, by feedstock.
SOILDrip Irrigation
Emitter spacing & flow planning.
SOILWatering Schedule
Frequency and depth by soil type.
SOILRain Barrel
Storage volume for roof catchment.
SOILRaised Bed Soil
Soil volume needed at any length × width × depth.
BEDSquare Foot Garden
Cells per bed by crop density.
BEDRow Spacing Planner
Rows + plants fit your garden.
BEDContainer Size
Gallons of soil needed per plant by crop.
BEDVertical Garden
Crops per tower by trellis height.
BEDFence / Trellis Height
Wind protection + trellis geometry.
BEDPollinator Garden
Plant list for bee-friendly borders.
BEDGDD Tracker
Daily growing degree days — heat-unit accumulation.
CLIMChill Hours Accumulator
Winter chill hours for stone fruit, blueberries, perennials.
CLIMFrost Risk Probability
Re-derive frost dates at 30% / 10% risk levels.
CLIMSeason Length
Days between last spring frost and first fall frost.
CLIMDaylight Hours
Hours of sun your garden gets by date + latitude.
CLIMEvapotranspiration
Daily water demand by crop.
CLIMYield Estimator
Per-plant yield for vegetables.
YLDSeeds to Buy
Total seeds (germ loss + oversow factor).
YLDCompanion Planting
Are these two crops good neighbors?
YLDCrop Rotation Planner
4-year rotation by family.
YLDCover Crop
Mix and seeding-rate planning.
YLDRain vs Supplemental
When to skip watering based on recent rain.
YLD22 crop planting guides
Companions, antagonists, soil temps, spacing, days-to-maturity, pest alerts, harvest notes — sourced to public-domain extension publications.
All 26 USDA hardiness zones
Full USDA Plant Hardiness Zone Map 2023, with localized frost dates, GDD, daylight, chill hours, and crop recommendations per zone.
| Zone | Winter Low | Growing Season | Avg Last Frost | Avg First Frost |
|---|---|---|---|---|
| 10a | 30°F – 35°F | 340 days | Mid to late January | Late December / frost-free in most years |
| 10b | 35°F – 40°F | 360 days | Early January | Frost-free in most years; occasional late December frosts |
| 11a | 40°F – 45°F | 365 days | Frost-free year-round | Frost-free year-round |
| 11b | 45°F – 50°F | 365 days | No frost ever | No frost ever |
| 12a | 50°F – 55°F | 365 days | No frost ever | No frost ever |
| 12b | 55°F – 60°F | 365 days | No frost ever | No frost ever |
| 13a | 60°F – 65°F | 365 days | No frost ever | No frost ever |
| 13b | 65°F – 70°F | 365 days | No frost ever | No frost ever |
| 1a | -60°F – -55°F | 92 days | Late May | Late August / early September |
| 1b | -55°F – -50°F | 105 days | Mid-late May | Early September |
| 2a | -55°F – -50°F | 110 days | Mid to late May | Early September |
| 2b | -50°F – -45°F | 120 days | Early to mid May | Early September |
State-specific planting calendars
Planting calendars and frost dates for 20 states. Each page includes month-by-month planting guide and zone-by-zone breakdown.
Guides
Understanding USDA Hardiness Zones
Read the guide →
How Frost Dates Work
Read the guide →
Growing Degree Days Explained
Read the guide →
Companion Planting Basics
Read the guide →
Crop Rotation Guide
Read the guide →
Seed Starting Indoors Step-by-Step
Read the guide →
Succession Planting Explained
Read the guide →
About SproutZones
Free, no signup, no tracking. Data sources: USDA Plant Hardiness Zone Map 2023, NOAA NCEI 1991–2020 climate normals, and public extension service publications.
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