I really enjoyed
Old Herbaceous by Reginald Arkell, which I read last year.
Old Herbaceous is a classic British novel of the garden, with a title character as outsized and unforgettable as P. G. Wodehouse’s immortal butler, Jeeves. Born at the dusk of the Victorian era, Bert Pinnegar, an awkward orphan child with one leg a tad longer than the other, rises from inauspicious schoolboy days spent picking wildflowers and dodging angry farmers to become the legendary head gardener “Old Herbaceous,” the most esteemed flower-show judge in the county and a famed horticultural wizard capable of producing dazzling April strawberries from the greenhouse and the exact morning glories his Lady spies on the French Riviera, “so blue, so blue it positively hurts.” Sprinkled with nuggets of gardening wisdom, Old Herbaceous is a witty comic portrait of the most archetypal—and crotchety—head gardener ever to plant a row of bulbs at a British country house.
Got it from the Internet Archive - there were a few OCR errors, but not too aggravating IMO.
https://archive.org/details/oldherbaceou00arke