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About this tool
Work out plants per bed, weekly watering and the harvest date from your spacing, zone and sowing date, then build a planting prompt.
The Gardening Prompt Builder turns a bed size, a plant spacing and a sowing date into the numbers a growing plan actually needs — how many plants fit at square spacing, how many litres a week the bed needs at the standard 25 mm (1 inch) guideline, and the date maturity falls due — then writes an AI prompt around them. It also converts a USDA hardiness zone into its defined minimum-temperature band and warns when a tender crop is being sown before the last spring frost. For kitchen gardeners who want a plan tied to their plot, not to a generic article.
Open Gardening Prompt Builder on AltFTool — it loads instantly in your browser.
Enter Crop or plant, USDA hardiness zone, Bed length (cm), Bed width (cm) and Plant spacing (cm).
Add Days to maturity, Sowing date and Last spring frost date so the harvest date and the tender-crop frost warning can be worked out.
Read Plants that fit at this spacing with Bed area, Water at 25 mm a week and First harvest, then press Copy prompt to take the generated planting prompt.
Whole plants only, along and across, so the count matches what will really fit.
Zone 7b resolves to its official 5 to 10 °F band rather than a vague description.
Sowing date against last frost date, with hardiness-aware warnings for tender and half-hardy crops.
At square spacing it is floor(bed length ÷ spacing) multiplied by floor(bed width ÷ spacing) — partial spaces do not count. A 240 × 120 cm bed at 45 cm spacing gives 5 along by 2 across, so 10 plants.
The long-standing guideline is about 25 mm (1 inch) per week from rain and irrigation combined. Because 1 mm of depth over 1 m² is exactly 1 litre, that works out to 25 litres per square metre — roughly 72 litres a week for a 2.88 m² bed.
Zone 7b means the average annual minimum winter temperature is between 5 and 10 °F (about −15 to −12 °C). Each whole zone spans 10 °F and the a/b halves split it into 5 °F bands; the zone describes winter cold only, not summer heat, rainfall or season length.
Not outdoors — tomatoes are tender and a single frost usually kills them, so plants go out only after the last spring frost date. You can start seed indoors roughly six to eight weeks earlier and transplant once nights are reliably above freezing.