Frost-night alerts and planting dates for backyard gardeners

The problem

A single frost night can kill tomato and pepper transplants, and gardeners often find out too late to cover them. Weather apps show the overnight low but don't connect it to what's planted. Garden planners cover sowing calendars, usually as yearly subscriptions built around drawing bed layouts.

For: Backyard vegetable gardeners · Raised-bed and balcony growers · Community garden members

Why now

The National Weather Service's forecast API is open data and free to use for any purpose, and NOAA's 1991-2020 climate normals publish more than 500 statistics, including growing-season lengths and probabilities of key variables.

Demand signals

Monthly Google searches in the US, pulled 2026-09-24. These are the words people with this problem actually type.

• last frost date seasonal4,400
• vegetable planting calendar1,300
• first frost date880
• frost dates by zip code880

“last frost date” is seasonal: searches peak from February to April and drop to about 400 a month in summer.

What exists already

• Seedtime ↗Turns frost dates into a weekly sowing plan; the free plan covers one calendar, paid plans from $7/month billed yearly.
• Planter ↗Bed-layout app with a growing calendar; the free tier is limited to one garden with ads, Premium $24.99/year.
• GrowVeg ↗Layout-first planner, paid only after a 7-day trial ($35/year recurring).

MVP scope

1. Push or text alert when the forecast low at your ZIP hits your threshold
2. Separate alert thresholds for tender and hardy crops
3. Average last and first frost dates from NOAA climate normals
4. Sowing, transplant and succession dates for the crops you list
5. Weekly 'do this now' list
6. Harvest log to adjust next year's dates