But maybe a nice bouquet of flowers if it's a women, for instance, or a gift card to a restaurant, like mentioned, or a box of nice chocolate and such.

Sending flowers?

And stage with artificial flowers inside and out 

This brings you to cities like East LA, Bell Flower, and Paramount.

flowering shrubs?

Some guy wanted it to plant flowers in.

New siding really makes a house pop. as well as new bushes in the front and a hundred bucks on flowers if your property is marketed between april and oct.

If guests ask me about flower delivery, for example, I can refer them to a local florist but it doesn't happen often enough for me to go to the hassle of figuring out how to execute it myself (much less mark it up enough to be worth my while but not so high guests say "forget it")That said, if you have a very large portfolio of properties in a particular area where demand for certain things is high, it might be worth figuring out.  

It’s the plant (flowers) themselves that are really pungent, so if people don’t store it (or the used burnt bits) in a closed container, the smell from that is noticeable.

One other thing I'd suggest is giving them hand written cards at unexpected moments.Ex. if you have balconies and they have flowers on them you can give them a note saying you love the balcony.I'm doing this at a 168-unit class C community and it's amazing the responses we get.