The flowers that suit distance
An orchid with a lotus is the pairing for someone far away — steady, patient, calm. A camellia alone carries the same idea with a little more longing in it.
If you want something warmer, a rose with a camellia splits the difference: love, plus the distance.
Write for the time difference
They will open it at 7am their time or 11pm, and it will read the same either way. Say where you are when you are sending it — “it is raining here and I am at the kitchen table” — because that detail collapses the distance more than any sentiment does.
One thing that works better than you would expect: naming the next time you will see them. A date beats a reassurance.
The small everyday version
Long distance is not made of anniversaries. It is made of the Tuesday you miss them and say so. The bouquet is cheap enough to be a Tuesday thing, which is exactly why it is useful.