Bob Hobden wrote:

So we in the south can all grow olive, lemon and orange trees in our
gardens...news to me, they won't survive in most of warmer London either,
only in specific garden microclimates (like Dave Poole's). You need to drag
them back inside to avoid the frosty weather.

There are a few folks growing lemons, mandarins and even avocados
within the London conurbation Bob, but most of the oranges need more
heat. Outside of the 'heat-sink' area, the frequency and intensity of
winter frosts is too great. Of course gardening luvvies like these
don't worry about such trivia. They are only concerned with the
immediate effect and never stop to consider what happens over the
ensuing months and years.

Oranges will grow here and produce fruit, but the sweet flesh does not
develop at low temperatures so they are only useful for ornament or for
using the rind/zest in cooking. I've been experimenting with Limequats
recently. This is a hybrid between the Florida Key lime and Nagami
Kumquat. Limes need a lot of heat to grow well and are the least cold
resistant of the citrus family. However, the kumquat is remarkably
cool tolerant and the fruit develops quickly. These qualities are
passed down to the hybrid although the fruits are quite small. Mine
flowered in June this year and I picked several fruits this weekend.
The flavour was excellent. Pick them green if you want a lime, wait a
couple of months and pick them yellow if you want a semi-sweet lemon.

Back to this programme, 'Digging Deep' quickly reached the expected
nadir of pseudo-horticulture and managed to keep me awake for less than
10 minutes. What I saw was pretentiously plebby and about as gripping
as a blancmange handshake. However, on the bright side, I got a good
couple of hours unexpected zzzz so for me it was therapeutic.