Just like humans, indoor plants respond to a bit of TLC and attention. Here is the first of two articles that will help teach you how to go about this. However, there are strong views about how far you should go in the pursuit of perfection, with foliage polishing being a divisive subject within the indoor plant community.
Dust is an enemy in several ways:it spoils the appearance of the foliage; it blocks the leaf pores to that the plant can no longer breathe properly; it forms a light-blocking screen so that the full effect of daylight is lost; and it may contain plant-damaging chemicals.
It is therefore necessary to remove dust when it becomes obvious on the foliage. Small plants can be immersed in a bucket of water, but it is more usual to sponge the leaves with clean water, either using a gentle damp cloth or cotton wool. For larger plants, it is not uncommon to give them a cool shower all together for a few minutes. Of course they will then need to sit and drain for sometime afterwards and I dare so this will also create a bit of a mess too.
It is a good idea to attend to this task earlier in the day so that the foliage is dry before night time. For mature foliage that is very dirty, it should be lightly dusted with a soft cloth/cotton wool or even feather duster before washing-failure to do this may result in the dust turning into a muddy coating when the water dries.
If you do decided to use a cloth or cotton wool method with the plant in situ, remember to support the leaf in your hand when washing a mature leaf. For fresh, more delicate growth/ a syringe may be a better option for you, which you can buy from any pharmacy. Cacti, succulents and plants with hairy leaves should not be sprayed or washed; use a soft brush to remove dust.
Foliage, even when clean, tends to become dull and tired-looking as it ages; the glossy sheen of the new leaf is soon lost. Clearly this is a matter of personal taste but US based indoor plant bricks and mortar and online shop "The Sill" are dead against leaf shine, as evidenced in their blog article https://www.thesill.com/blogs/care-miscellaneous/just-say-no-plant-shine
According to The Sill......
"First things first: We do not recommend using leaf-shining products on your houseplants. EVER.
There are many commercial plant shine products are on the market and many retailers who use it to beautify their plants today. Not us! Leaf shining products are not beautifying, they’re bad! Plants breathe through their leaves through little pores called stomata and many leaf shine products end up clogging these stomata with either oil or wax. It’s just like your skin – you get blemishes when you have too much residue blocking your pores. The difference is, plants don’t get pimples. Their clogged pores mean suffocation and maybe even death.
The high shine look is not a good one. It’s very artificial and you may be inclined to forget that your plant is a living thing, not plastic decorum. Aside from looks, the upkeep is a headache. The oils and waxes from shine products end up sticking to dust in a clumpy way that au naturel leaves do not. Dust build up makes it more difficult to clean your plant and you’re in an endless cycle of cleaning and reshining.
The Sill has a very good point, for our personal collection at Home of Houseplants, we never shine our foliage, we are fans of the natural look. Some people however lust after that glossy shine, I totally understand, it is all a matter of personal taste in our view, so what options do gloss lovers have?
Plant polishing materials are available but you do need to proceed with care. First and foremost, is your plant suitable to "polish"? For example a fiddle leaf fig, a common rubber tree or even a monstera deliciosa have large, smooth foliage that will respond well to polishing. By contrast a delicate and velvety Peperomia incana or Philodendron melanochrysum will not respond well, and will look worse after such treatment. Let the texture of the leaf guide you. If it is smooth-leaved, generally speaking, it should respond well to a polish.
In the past, we have heard of many weird and wonderful recommendations, including milk, beer and olive oil. These will at first instance will produce a shine, but will also smell, collect more dust and can cause damage, they are to be avoided at all costs. For this reason it is important to buy a product which is specially made for plants-both wipe-on liquids and aerosol sprays are available.
Aerosols are simple to apply, but are not suitable for repeat treatments at regular intervals. Leaf shine liquids can be safely used on a wide range of smooth-leaved house plants; apply by gently wiping foliage with a piece of cotton wool impregnated with the liquid. There are a few rules when polishing, which include:
1) Do not polish young leaves and never press down on the leaf surface.
2) Read the label on the product you choose - you will find a list of plants which should not be treated.
3) Do not apply if or when direct sunlight is on foliage.
If you do decided to use a leaf shine product, despite the advice of many to the contrary, it is important to not allow the product to build up on the foliage and for it to be washed and perhaps rested between shine treatments.
Here are the links to the leaf shine products that are most commonly used in Australia.
In preparing this article, Home of Houseplants wishes to give credit to the awesome vintage indoor plant book, "The Gold Plated House Plant Expert" by Dr D.G. Hessayon, which has been referenced and paraphrased in this article.