The Garden Almanac
Every spring I have the same argument with myself in the seed aisle. The tomatoes are right there, the afternoon is warm, and some optimistic part of my brain insists it’s fine to put them in the ground this weekend. The cautious part remembers the year a late-May frost flattened a whole flat of seedlings overnight. Gardening, it turns out, is mostly about timing — and timing is mostly about frost.
So I built a tool that settles the argument. It’s called The Garden Almanac, and it lives here:
You type in your ZIP code. That’s the whole setup. From there it tells you three things gardeners are forever looking up: your USDA hardiness zone, your average last and first frost dates, and how long your growing season actually is. For me here in Neenah it comes back with Zone 5b, a last spring frost around the end of April, a first fall frost in mid-October, and roughly 165 frost-free days in between to work with.
A planting calendar that knows where you live
The frost dates are the foundation, but the part I actually use is the planting calendar. Instead of a generic “start tomatoes 6 weeks before last frost” that leaves you doing arithmetic, it does the arithmetic for your location and just gives you the dates: start these seeds indoors on this day, set the transplants out on that day, direct-sow the beans the week after, and here’s roughly when each one is ready to harvest. There are more than fifty crops in there — the cool-season stuff like peas, spinach, kale and lettuce; the warm-season tomatoes, peppers, squash and beans; herbs; a pile of annual flowers; and even a few of the perennials I grow, with a note on when they typically wake up in spring.
There’s also a little “what to do in the next few weeks” list at the top, so you don’t have to scan the whole calendar to know what’s timely right now. Each crop opens up into a proper growing guide too — good varieties, how deep to sow, spacing, what to plant it next to, what pests to watch for, and how to tell when it’s ripe.
Frost Watch, for the nervous nights
The averages tell you the season; Frost Watch tells you about tonight. It pulls the live forecast lows for the next two weeks and flags any night cold enough to threaten tender plants — the cue to throw a sheet over the tomatoes before bed. You can even nudge it for your own spot: a sheltered city yard runs a few degrees warmer than the forecast, and a low-lying frost pocket runs a few degrees colder.
Real data, honestly labeled
The frost dates aren’t guesses. They come straight from NOAA’s 1991–2020 Climate Normals — the official 30-year freeze records — from the nearest of about 1,100 weather stations to your ZIP. The zone is from the 2023 USDA hardiness map. But I’ll say the honest part out loud, the same way the tool does: these are averages and probabilities, not promises. A frost date is the middle of a range, and your own yard has its own microclimate. When a tender plant’s life is on the line, watch the actual forecast and give yourself a cushion. The Almanac shows you the early-and-late range for exactly that reason.
Free, private, runs in your browser
Like the rest of the tools in the Workshop, there’s no account and no ads. Your zone, frost dates and calendar are all worked out right on your device from data that ships with the page — the only thing that ever leaves your browser is your ZIP code, to look up where you are and (on Frost Watch) to grab the forecast. You can even add it to your phone’s home screen and it’ll open like an app.
If you’ve ever stood in the garden wondering whether it’s safe to plant yet, this is the answer in about ten seconds:
Find your frost dates & planting calendar →
— Jamie
