As you may be aware there have been major problems with the importation of aquarium plants over the last few years. Quite a few former suppliers are now unable to send plants to the UK.
To meet the very strict import requirements into the UK, plants have to be sprayed with insecticides to kill any bugs or larvae that might be on them.
For this reason we strongly recommend that all plants should be thoroughly washed before introducing them to livestock and especially invertebrates, particularly crustacea. To be completely safe if plants are to be placed in shrimp/crustacea aquariums then it would be a good idea to isolate them for a couple of weeks beforehand.
It is very unlikely there will problem but it is better to take all necessary precautions.