Diwali flowers are used more often than they are held
Most of a florist's work leaves the shop as something to hand over. Flowers for Diwali frequently leave as material instead: a garland for a doorway, a low arrangement for a table that already has dishes and lamps on it, loose heads to be laid out in a pattern on a tray or a floor. The order behaves differently from a wrapped bouquet, so it helps to say which of the two you want before anything is built.
A tall bouquet in paper is the one shape that struggles here.
Formats that actually get put out
Tables fill early, and height is the first thing to lose. A low arrangement on soaked foam or in a shallow basket sits between the dishes without blocking the view across the table, and a passing sleeve will not take it over. Garlands run along a stair rail, a door frame or the edge of a counter, and marigold does that job because the head keeps its shape out of water and a strung line of it does not sag under its own weight. Separate heads and petals go into floor patterns, where colour decides everything and stem length decides nothing. A household doing all three is better served by one order covering garland, table piece and loose heads than by a second delivery on a crowded day.
Keep the scent quiet. Food is the point of the evening, and a lily in the middle of the table will compete with it.
A flowering plant in a pot is the other honest answer. It stays after the lamps are put away, it asks nothing of the host on the night, and it can be carried into a hallway or a balcony afterwards. Cut stems in that setting rarely last past the weekend.
Colour under lamplight rather than daylight
The room is lit low and warm. Under that light lilac, pale blue and dusty pink lose about half their saturation and drift towards grey by the end of the evening. Orange, gold, deep red and magenta hold their strength. Cream and ivory sit more easily beside a flame than pure white, which yellows unless there is dark foliage or a strong accent beside it.
Photograph a shortlisted bouquet under a table lamp rather than by a window and you will see roughly what the evening is going to do to it.
Bringing it and sending it
Flowers taken to a host go in at the door with everything else, and the household decides where they end up. That argues for a finished arrangement rather than stems that need a vase and ten minutes at the sink. A basket or a box that can be set down as it is will be set down, while a wrapped bundle waits on a counter until somebody has a spare hand.
Business gifts run on a different clock. They travel before the holiday rather than during it, since offices empty early, and the safer register is a warm palette without romantic signals, which in practice means red used alongside orange and gold rather than red roses on their own.
When to place the order
The date moves each year on a lunisolar calendar, so the month is no guide and the date itself is. Demand compresses into two or three days. What runs out first is not flowers in general but the warm end of the palette, and orange and gold go before anything else. An order placed several days ahead leaves the florist a choice, while one placed the night before is a list of whatever is left in the cold room.
Delivery in Mumbai is easier in the morning. By evening the house is decorated and running to its own schedule, and a courier at the door becomes one more thing to deal with.