What is farina?
Epicuticular wax or farina is a coating of wax that forms a white or blueish silver film on the leaves of succulents. It is found on the stems, leaves and fruit of all different types of plants but it's most prevalent on succulents like Echeveria, Pachyphytum, Sedeveria, Kalanchoe, and Graptoveria, to name a few. Keep in mind that not all species in these genus examples have powdery farina.
If you've ever accidentally brushed against powdery leaves on your succulent, you probably noticed that it left a behind a little mark. What you're actually doing is removing the bloom and sadly, it can be irreversible depending on the species. If it does regenerate, it doesn't return to the level it was prior.
Epicuticular wax is actually tiny microscopic crystals that form on the cuticle of a plant's surface which help their water repellency (epi meaning 'on' or 'upon' because it grows above the cuticle on the epidermis). You may have also heard it called "farina" which is what I've always called it. Succulents that have this are said to be "glaucous" which simply means, according to Webster, "having a powdery or waxy coating that gives a frosted appearance and tends to rub off".
Does removing the epicuticular wax harm your plants?
The answer? Not really.
However, you should avoid removing it because it acts as a hydrophobic layer which also helps protect the plant from the sun, water, pathogens, and insects. Hydrophobic simply means that it repels water.
Avoid pesticides (which you should try to do anyway!) fungicides and horticultural oils like neem since these can completely remove the farina. For plants that have bugs AND farina, consider treating systemically as a soil drench. I have also used a 50% rubbing alcohol and water mix for mealy bugs and misted it onto farina covered leaves without any issue. Always test first and always allow to fully dry in the shade to prevent burn.
If you need to clean soil from the leaves of your plant, use a super soft makeup brush or blow it away. Avoid using your fingers since the oils on your skin can ruin the powdery appearance.
One thing that I really like about farina on succulents is that it helps to keep the leaves clean. Water beads up on the surface capturing dirt, microbes, and other particles then rolls them away. This is known as the Lotus Effect. Lastly, leaves that are succulent are able to stay nice and plump because the waxy coating not only keeps water out, it helps keeps it in as well!
Succulents with farina have a natural sunscreen, raincoat, antibiotic, and bug spray all-in-one, built right in!
Farina forms on all parts of the plant, everything from the stem to the leaves and even the flowers. The amount can vary depending on the species but also within the same species according to where it is grown (both in cultivation and in the wild). Farina is different from fuzzy, soft succulents which cannot be wiped away.
An even epicuticular wax layer is a sign of good plant health. If you notice a mottled appearance, it could be due to high humidity or even disease. This is why it's important to always examine your plants regularly (I don't even know why I'm mentioning this because I already know you stare at your plants for hours on end....OR IS THAT JUST ME? Don't answer that.
To this day I still remember my first experience with farina. It was super THICK on a flapjacks paddle plant right at the base and I just knew it was some sort of mold or disease. It was so heavy that it was falling off in little chunks (can you see why I worried?!). Turns out it was only epicuticular wax. *phew!*
So how do you tell the difference between farina and powdery mildew?
Well, since powdery mildew is caused from fungal spores, it starts out splotchy and slowly spreads whereas farina is more even across the surface of the plant. Powdery mildew will also begin to make your plant sick, causing it to deform and damage the appearance of leaves. This is another reason why it's important to always monitor the health of your plants. It's things like this that you want to catch before they spread to others.
When you get plants shipped in the mail, it's nearly impossible for them to arrive without some of the farina wiped away. You can see it here in the Echeveria Lauii below. The only thing to do is wait until it grows out (which this one did and now it looks amazing!). There is absolutely no need for alarm when this happens and is not the fault of the sender. It's just part of the process. It WILL grow out!
Also below is an example of an Echeveria pollux that arrived with the farina missing from most all of the leaves but has since grown out. As time went on - and new leaves grew from the center - they slowly worked their way to the bottom. The oldest leaves will eventually dry up and die as the plant grows (which is totally normal).
One thing that I found that was interesting while researching farina on succulents has to do with the Giant Chalk Dudleya (D. brittonii) that grow in fissures on steep volcanic outcrops. (Sorry I don't have a photo of one but you can admire this crest instead). There are two forms - one has thick, glaucous coating and the other does not, depending on where they grow. The brittonii that do have farina offer a whopping 83% UV reflectivity and is HIGHER THAN ANY OTHER PLANT SPECIES. (Say waaat!?) That being said, non-glaucous forms of the same species only offered 10% reflectivity!
Not only is powdery farina beautiful, it is important to plant health so if you have a succulent that has had it removed (because you accidentally cleaned the whole plant with horticultural oil like I have), it might be best to keep it sheltered from the sun until it's acclimated again. Remember, farina on succulents doesn't come back to the same way it was before so take care not to rub it off!
Have you ever had a plant regenerate it's farina? If so, let us know in the comments below!