ZIP code to hardiness zone
Type a US ZIP code and get its USDA plant hardiness half zone from the 2023 map's ZIP code listing, with the temperature band it stands for. The whole zone is what every plant page, the tree finder, the shop and the planting-site check use, so the result links straight into them. You can also have this device remember your zone, so the other tools offer it.
What the zone tells you
A hardiness zone is the average of each year's coldest night over thirty years, in ten-degree bands: zone 7 is 0 to 10 °F, zone 6 is -10 to 0. The half zone (7a, 7b) splits the band in two. It tells you which plants are likely to survive your winters, and nothing about your soil, your sun or your summers. The planting-site check asks about your sun and soil as well. Your hardiness zone is also called your growing zone or planting zone.
An older label or website may give the zone of the 2012 map, which averaged the winters of 1976 to 2005. The USDA puts the 2023 map about a quarter zone warmer across much of the country. Between PRISM's 2012 and 2023 ZIP code listings, more than half of the codes in the contiguous states moved a half zone warmer or more. The USDA adds: "What has thrived in your yard will most likely continue to thrive."
Ordering for your zone
Every plant page shows the zones the species takes, with your zone marked once this device remembers it. Live plants ship February to May and October to November. Ships for $15.00 to MD, DE, VA, PA, NJ, DC and WV and $25.00 to the rest of the contiguous US, per package; each extra item in the same box adds a little. The shipping page has the months, the shipping regions and the rates in full.
How the lookup works
- The 2023 listing. The lookup reads the ZIP code listing published with the 2023 USDA Plant Hardiness Zone Map, prepared by the PRISM Climate Group at Oregon State University with USDA's Agricultural Research Service, and shows each code's half zone exactly as listed, for the contiguous states, Alaska, Hawaii and Puerto Rico. The zones are based on the mean annual extreme minimum temperature of 1991 to 2020.
- One zone for each ZIP code. A ZIP code that spans two zones is listed under the zone that covers the largest part of it, so a spot inside the same ZIP code can sit in another zone. The official USDA map shows the zone of any spot you click, and it is the final word. This page is a lookup of that listing, not the map itself.
- A code the listing lacks is read from the listed codes that share its first three digits: their zone where they all share one, and the zones they span where they do not. The answer says so.
- Whole zones. Plant pages, the tree finder, the shop and the planting-site check work in whole zones, so the answer's links use zone 7 for both 7a and 7b.
- Our trees and shrubs for the zone. The count is the number of our trees and shrubs whose zones include yours, as the shop's zone filter counts them. The four named are the first the shop lists for that zone.
- Shipping. Where none of our shipping zones reaches a ZIP code's state, the answer says that we do not ship there.
- Remembering. Remember keeps the whole zone in this browser, on this device. The tree finder, the sowing planner, the bloom calendar and the planting-site check select it for you. The shop offers it as a filter, and every plant page marks it. Forget it clears it, and the state the sowing planner keeps beside it.
Where the zones come from
The quarter zone between the 2012 and 2023 maps is the USDA's figure, from its page Map Creation, and the line on what has thrived is from its How to Use the Maps. The share of ZIP codes that moved is our count from PRISM's 2012 and 2023 listings. What the zone leaves out, from summer heat to late frost, is in What a hardiness zone tells you about a tree, and what it leaves out. Why a zone edge is a poor reason to reject a tree is in Why the range maps are wrong.