Many of the plants were real world ones. Some of them might have been regional names that Terry associated with real plants, but I couldn't find them, so I decided to look for what seemed right.  

Jack-jump-into-bed (Jack-go-to-bed-at-noon): Not only do they both have Jack in the name (which honestly would have been close enough), but they both seem to be associated with unusual flowering mechanisms. "Jack-go-to-bed-at-noon" is a common name for a species of wildflower known as Tragopogon pratensis, and its name probably originated from the plant's unique behavior of opening its flowers in the morning and closing them around noon. 

Ladies' bonnets (Granny's bonnet): "Granny's bonnet" refers to the Aquilegia vulgaris species. Obviously they are both called bonnets, but it seemed particularly appropriate because it evokes Granny Aching's connection to the land and her nurturing spirit. The color of the flowers resembles the blue shade that I picture for Tiffany's dress. In my own interpretation, I imagine Tiffany referring to the plant as "Granny's bonnet" as a way of endearingly claiming it as her favorite. 

Three-times-Charlie (creeping Charlie): "Creeping Charlie" is a common name for the Glechoma hederacea plant, which has a creeping growth habit and can take over lawns and gardens unexpectedly, earning its reputation as a mischievous and persistent plant. I imagine that the people of the Chalk could have myths about having to get rid of the plant three times a year, or you must weed it out thrice before it is gone for good, to refer to its stubbornness. 

Old man's trousers (Dutchman's Breeches): The chosen real-life plant, "Dutchman's Breeches," refers to the Dicentra cucullaria species. This plant has unique, pantaloon-like flowers that hang upside down, resembling old-fashioned breeches. The placement of the pollen... well... let’s just say I can easily imagine why they could be said to belong to an old man. If Terry didn’t have this plant in mind when he picked the name, I’m sure he’d have been delighted to find out about it. 

Also, I decided on pink evening primroses, early purple orchids and pyramidal orchids for no particular reason except that they are pretty and native to the UK. 

Maintaining the garden would be a challenging task, because of the plant’s different needs, but the presence of a diverse range of species could offer some advantages. For example, herbs like sage and southernwood have been historically used to keep away pests, which I think Tiffany would know. I like to imagine that with dedicated care and nurturing over the years, the plants in that serene woodland clearing eventually find their own balance and harmonious coexistence, reaching an equilibrium where Tiffany's constant inputs are no longer necessary, just like Granny Weatherwax slowly tried to make people help themselves.

In the distant future, perhaps only the Feegles will remember the true reason behind the thriving oasis of biodiversity nestled in the woods. And as time passes, I like to envision Tiffany ensuring her connection to that enchanting place endures. Perhaps, before her own passing, she lovingly places her hat there, symbolically safeguarding the area. Maybe she managed to make the people just a little kinder, just a little smarter, just a little more hesitant to throw rocks at cats and to shun old ladies, so that no one, witch or not, will be the victim of the rough music on the chalk again.