tomatoseedlingsHURRYING TO THE STARTING LINE can make for mishaps such as false starts, so don’t. That’s my best advice on when to sow what seeds for this year’s garden, but I know it isn’t very specific. To zero in on just what date you should sow your tomatoes indoors or put your peas in the ground, I’ve rounded up some calendar tools that can help, including a new one just sprouted by my friend Dave Whitinger of All Things Plants.

It should be no surprise to me that it was Dave who created this new online application, since besides his garden expertise, Texas-based Dave is a programmer (and the founder of Dave’s Garden, which he ran before moving on to start All Things Plants). Dave was the guest on this week’s “A Way to Garden” public-radio show and podcast, where we discussed the new Garden Planting Calendar app. (Stream the show now; get it on iTunes, or Stitcher, or at RobinHoodRadio.com.)

“My wife, Trish, is actually the one who pushed me to do this,” says Dave, adding that the Garden Planting Calendar took him only two months to develop and launch. It gives you first and last frost dates (where applicable) and sowing and/or planting dates by crop, based on the location you enter.

The app started with just U.S. weather data, but Canadian users quickly said, “What about us?” so Dave added that information, too. He also programmed in the Wikipedia-like ability for users to help fine-tune the calendar by adding their city and frost dates if they didn’t find them, or to correct errors—and in fact “many hundreds” of gardeners from Israel to South Africa to Pakistan have already widened the tool’s now-worldwide scope, Dave says.

“I’m improving it daily; it’s almost still in beta,” he says. Last week’s addition: a map feature, so you can perhaps pick a better position than the one the zip or address finder (based on government data) identifies you with.

A caveat: Any application is based on weather data that isn’t as localized as your very own backyard, but rather from the nearest official stations. Calling your county cooperative extension or public garden first, for hyper-local advice, or asking experienced gardeners in your locale, will help beginning gardeners, in particular, to know how to adapt calendar recommendations slightly to be “just right.”

planting charts and calculators