Thank you flowers: pick the format the recipient can cope with
Gratitude usually reaches somebody while they are at work. A ward, a classroom, a kitchen, a service desk, a site office: places with no vase, no spare surface and nobody free to look after a bouquet for the rest of the shift.
That single fact rules out more formats than anything to do with colour.
A wrapped bouquet hands over a small job. Somebody has to find a container, trim the stems, top up the water and then carry the whole thing home at the end of the day, usually standing on public transport. An arrangement in a low container with floral foam asks for none of that: it is set down where it lands, topped up every few days, and it travels flat in a car boot. A hat box behaves the same way and hides the foam underneath the heads. On a desk, low beats tall, because anything that blocks a sightline gets moved within the hour.
Preserved roses in a box remove the water question altogether. They last one to three years, need no attention at all and occupy roughly the footprint of a mug, which is why they end up on reception counters and nurses' stations.
Scale, and the trap inside it
Thanks that are too large stop being thanks. A big arrangement sent after a real favour reads as settling an account, and the person who helped starts wondering what comes next.
Modest and specific works better than generous and vague.
The exception is family, where nobody is keeping score and a large bouquet is simply a large bouquet.
Colour
Red roses are the one thing to avoid outright, since they answer a question nobody asked. White, cream, peach, soft yellow and muted lilac all read as warm without implying anything further. Spray roses, alstroemeria, chrysanthemums, lisianthus and a little greenery hold up well in a warm room, which matters when the flowers will stand under office lighting for a week. Strong mixed colour says more about the sender's taste than about the occasion.
Scent is worth checking before ordering, because clinics and open-plan offices often have rules about it.
The note
A card counts for more here than at any other occasion. Flowers with no message leave the recipient guessing which favour is being acknowledged, particularly if helping people is what they do all day. One plain sentence naming what they actually did carries further than another ten stems.
Write it the way you would say it out loud, and sign with the name they will recognise.
Getting it there
Workplaces have narrower delivery windows than homes do. Before the shift starts there is nobody at the desk, and after it ends the flowers spend the night with security and reach their owner a day later with the moment gone.
For a courier in Manchester the safest instruction is a named person, a time inside working hours and a phone number somebody will pick up. Where a building has a reception, saying who should be called on arrival keeps the bouquet from being signed for by a stranger and parked in a back room until somebody remembers it.