Zebra finches are remarkably different in character to Bengalese and Cherry finches, taking little to no interest in any vegetation we have decorated their cage with in the past. Bengalese and Cherry finches however, seem quite similar in nature. They both take interest in decorative vegetation, and they both seem more agile than Zebra finches.
Both the Bengalese and Cherry finches enjoy hanging on vertical objects, and we have witnessed both species eating while hanging upside down! The Cherry finches however, enjoy this vertical hanging more, and their nails grow at a faster rate. Having done a bit of reading, it seemed that this was common for finches that would enjoy and benefit from the presence of reeds.
As such, earlier in the week we bought some reeds (bamboo is also safe to use), cleaned them with bird safe disinfectant and anti-mite sprays, bundled them at one end then poked them through the cage. Both the Bengalese and Cherry finches seem to enjoy them, hanging and interacting with them regularly.
Today, we expanded this theme by buying a small bamboo plant (clear of pesticides) and placing it in one corner of the cage. Within seconds all of the birds in the cage were next to it in amazement! So far they seem to enjoy it and have not stopped playing with it since it was put in a few hours ago.
It should be noted that care is to be taken when introducing live plants to your finches, as quick a lot of plants (stem and/or foliage) is toxic to birds. If you are unsure, please check: http://www.parrot-and-conure-world.com/non-toxic-for-birds.html