City growing season can be 10 days longer

Compared with their rural counterparts, urban gardeners get as much as one extra week for their peas to germinate, tomatoes to flower and courgettes to fruit. This lengthened growing season is thanks to the urban heat island effect, according to a new study. But the extended growing season is not all good news. For some plants the enhanced summer temperatures combined with a shorter winter hibernation period is stressful, and for bugs and bees the syncopated rhythm to the growing season can cause major confusion.

The urban heat island effect occurs in towns and cities all over the world, with the high density of tarmac, cement and brick all acting to increase local temperatures. The impact on people is well known, but how does the urban heat island affect plants and trees?

Samuel Zipper from the University of Wisconsin-Madison, US, and his colleagues addressed this question by closely monitoring the temperature across their home city of Madison. Using an automated temperature sensor network along with remote sensing data, they assessed the impact of urban heat on