About half of the country moved into a slightly warmer zone in the Agriculture Department’s new “plant hardiness” map, an important guide for gardeners. Climate change may be a factor.
I’m a bit disappointed in the USDA’s approach here. Basing the model on historical data, the map is already out of date at the time of its release. Right now the difference will be small, but by the time we get close to the next update, the difference could be considerable. This could be a barrier to planting species that are more likely to survive our future climate.
The only thing the USDA map shows is the average lowest yearly temperature. The implications of this map for planting seem pretty minimal, because these are just averages over time and definitely do not represent the actual lowest temperatures you should expect where you live. There’s a lot to worry about with our changing climate, but this map wasn’t designed to convey any of that other information
The maps are designed to tell you which plants will survive if you plant them. They’re widely used by landscape architects and the likes for that purpose.
Only which plants will survive the average lowest temperature. There are still years where the lowest low goes well below average and kills even some hardy native species, eg in Central Texas in Feb 2021 it hit 4° in zone 8b, which has an average lowest low of 20-25°. This map is a general guide and should not be relied upon alone by landscape architects. This USDA map doesn’t impart any information about average rainfall or humidity, average cloud cover, or average high temperature, elevation, soil type, and lots more…only the average lowest yearly low temperature
A lot of what you mentioned will have different effects on different plants, you would need a different map for each one. Lowest average temp seems to work well enough given it’s still widely used.
I’m a bit disappointed in the USDA’s approach here. Basing the model on historical data, the map is already out of date at the time of its release. Right now the difference will be small, but by the time we get close to the next update, the difference could be considerable. This could be a barrier to planting species that are more likely to survive our future climate.
The only thing the USDA map shows is the average lowest yearly temperature. The implications of this map for planting seem pretty minimal, because these are just averages over time and definitely do not represent the actual lowest temperatures you should expect where you live. There’s a lot to worry about with our changing climate, but this map wasn’t designed to convey any of that other information
The maps are designed to tell you which plants will survive if you plant them. They’re widely used by landscape architects and the likes for that purpose.
Only which plants will survive the average lowest temperature. There are still years where the lowest low goes well below average and kills even some hardy native species, eg in Central Texas in Feb 2021 it hit 4° in zone 8b, which has an average lowest low of 20-25°. This map is a general guide and should not be relied upon alone by landscape architects. This USDA map doesn’t impart any information about average rainfall or humidity, average cloud cover, or average high temperature, elevation, soil type, and lots more…only the average lowest yearly low temperature
I agree that it’s not enough but it’s enough to rule out a lot of plants and narrow down choices.
I agree with that for sure, it’s a great starting place to judge what may work in your area
A lot of what you mentioned will have different effects on different plants, you would need a different map for each one. Lowest average temp seems to work well enough given it’s still widely used.