The color-coded map of planting zones on the back of seed packets is being updated by the U.S. Department of Agriculture to reflect climate changes brought on by global warming. The new guide, last updated in 1990, reflects, for instance, that the coldest day of the year isn’t as frigid as it used to be, so some plants and trees can now survive farther north. Nearly entire states, such as Ohio, Nebraska and Texas, are now classified in warmer zones.

The new guide uses better weather data and offers more interactive technology. Gardeners using the online version can enter their Zip code and get the exact average coldest temperature. For the first time, calculations include more detailed factors, such as prevailing winds, the presence of nearby bodies of water and other local topography.

Boston University Biology Professor Richard Primack observes, “There are a lot of things you can grow now that you couldn’t grow before. People don’t think of figs as a crop you can grow in the Boston area. You can do it now.” The changes come too late to make this year’s seed packets, but they will be on next year’s, says George Ball, chairman and CEO of the W. Atlee Burpee seed company.

View the planting zones map at Tinyurl.com/7r5u267.