Producing a guide to America’s (and Canada’s) gardens comes with both the advantages and disadvantages of a broad North American sweep. It ensures that wherever you travel the book has an interesting visit to suggest, but some states have so few entries that they may all be hundreds of miles from where you happen to be.

Entries are crisp and to the point, with symbols to highlight many features, and there’s enough to tempt you to look for more information on those that are especially appealing. But: “Smart-phone scannable QR codes that link to every garden’s website,” says the back cover and the publisher’s website. No. Of nine entries for South Carolina, a state picked at random, only three gardens have QR codes.

I can’t help but feel that the information should come not only as this useful book but as an app and a website where you can just put in a zip code (postcode) and see what’s nearby.

• A useful throw-in the-suitcase book for American and overseas travellers.
• Needs an app and website which includes far more gardens

The Visitor’s Guide to American Gardens by Jo Ellen Meyers Sharp is published by Cool Springs Press.