In article , Dave
writes

Kay writes
the plant database that this is based on is unlikely to be as finely
divided as post code areas - it's probably 1km squares, or even 10km
squares. When you type in your post code, it finds the square that your
postcode lies in, and gives you all the plants for that.

If it was by the full postcode it could tell me what to plant in my own
garden - my code is unique :-)

As you say, I suspect its by the first few elements.

A lot less than that!

If you read the info on the site, the underlying database is based on
10km squares. If any part of one of the 10km squares falls in your
postcode region (as defined by the first half of the postcode only) then
all the plants of that square are included - so if your postcode was
where 4 squares met, then it could be including all the plants from a
20km x 20km square!

And it includes historical records too.
--
Kay
"Do not insult the crocodile until you have crossed the river"