We recommend and use ourselves, liquid fabric softener and water. 30% liquid fabric softener and 70% water. The purer the water the better. Not the extra concentrated softener either but the regular strength softener. Any fagrance you care for.
It takes longer up front but this is the most effective ways to clean silk plants.
Spray a cloth and wipe the leaves until clean. I realize this takes longer but it is well worth it in the long term.
The reason it's better for the long term is because after the second or third time of doing it, the leaves become, for a lack of a better way to say it, "scotch-guarded ... the softener takes the fangs off the dust so that it doesn't stick as easy to the leaves. At this point you can use a can of computer air or a small compressor to blow the dust off. Hence, a little more work up front but a lot less work in the long run.
This works on plants for the same reason why most folks don't use softener when washing their bath towels, (because it keeps the towels from soaking up the excess water after a shower) ... the converse is then true about cleaning the plants, it keeps the leaves from attracting dust easily.
Some people ask about the spray cleaner that you spray on to clean a plant. The spray is not a cleaner but just a dust-cover-upper. If you spray something on a plant without wiping off the dust with it, you have just covered and hidden the dust, but haven't removed it. In essence, the spray just "lacquers" on each layer of dust until it's impossible to clean the plant at all after a while. I've seen where folks have used it so many times it looks like the plant has a layer of white all over it that no matter what one does, it can't be cleaned.
If you have any questions about this or want to hire us to clean your plants, feel free to call us anytime.
Gregory Yodis
ParamountSilks.com