Mono bouquets in Hong Kong: a chrysanthemum for good news, a narcissus alone
Among mono bouquets in Hong Kong, the chrysanthemum has its own place at the Lunar New Year fairs, held on a date the lunar calendar sets each year, where it stands beside narcissus, peonies, flowering peach and kumquat trees. In Chinese tradition the chrysanthemum stands for longevity, and a single-variety bunch keeps that meaning on its own rather than losing it among other flowers. With one flower in the vase, the colour and the stem count are both visible at a glance, which is where choosing a bouquet should start.
Chrysanthemums and carnations for good news: pink, red or peach
In Hong Kong a white chrysanthemum reads as mourning, and white flowers in general stay away from a birthday, an anniversary or a wedding. For a happy occasion the colour to choose is red, pink or peach, and a chrysanthemum is one of the simplest mono bouquets in Hong Kong to get right once that one rule about white is out of the way.
Both chrysanthemums and carnations hold up well once cut, each lasting two to three weeks in the vase, longer than most of the catalogue. A chrysanthemum's leaves tend to yellow before the bloom does, and pulling the yellowing ones off keeps the water cleaner and the remaining stem looking fresher for longer.
The carnation carries its own date here: it is the flower of Hong Kong's Mother's Day, the second Sunday in May. One more point worth knowing with either flower: a stem count of four or fourteen is best avoided, since in Cantonese the word for "four" sounds like the word for "death".

A few hydrangea heads, or lilies in colour rather than white
Large-headed flowers need fewer stems to read as a full bouquet: a hydrangea or a lily can look complete with just a few stems. Treat that as a guide rather than a rule, and mention it to the florist if a fuller bunch is what's wanted.
Hydrangea drinks more than almost anything else in the catalogue and takes up water through its petals as well as its stem. A drooping head recovers if it goes into cool water, flower first, for an hour or two, but past four or five hours in the water the soak does no more good.

Air-conditioned flats dry the air around a bouquet, hydrangea most of all, so a spot away from the vent keeps it going longer. For a wedding or a birthday a lily is better chosen in colour than in white, which again belongs with mourning flowers rather than celebration. A lily bunch is also not the right gift for a flat with a cat: every part of the plant, pollen and vase water included, is toxic to cats.
Narcissus and tulips in winter, each in a vase of its own
Winter brings two more flowers worth keeping as their own mono bouquets in Hong Kong rather than mixed into something bigger. Narcissus is one of the flowers the New Year fairs sell alongside the chrysanthemum, and that alone is reason to give it its own water: its cut stem leaks a sap that shortens the life of whatever else shares the vase with it. Left standing alone for about a day, narcissus settles, and after that first day its stems are not cut again.
Tulips sold here are grown under glass and cut from December through to May. A Hong Kong winter falls right inside that window, so a flower usually associated with spring turns out to be a winter one here. Fill the vase about a third full with cold water, no higher, since a tulip keeps drinking and stretching after it is cut, and the level needs watching rather than topping up once and forgetting it.
Every bouquet here is put together only once the order is placed, and a photograph of the finished flowers goes to the sender before the courier leaves. Most orders reach the recipient on the day they are booked, and the exact timing for mono bouquet delivery in Hong Kong is shown on each bouquet's own page rather than promised in the text. The centre of town is covered free of charge, and the outer districts carry a flat charge by delivery zone. A reasonable place to start is a chrysanthemum in red or peach for good news, a handful of hydrangea heads for a fuller look, or a tulip kept to its own vase through the winter months.