Why are my variegated plant's leaves turning brown?

Monstera Thai Constellation, Ficus Tineke, Monstera Albo, Philodendron Pink Princess, Manjula Pothos [add your variegated plant here]... the list of variegated plants prone to browning is a long one. I have bad news and good news for you. The bad news is you can't reverse the damage already done (except for one reason, coming up). The good news is there's a lot you can do to stop it getting worse and to help prevent it happening on more leaves. There is hope. And the quicker you act the sooner the browning will stop...

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Why are only the variegated parts of the leaves turning brown?

Variegated leaves are weaker. For most plants, it's the lack of chlorophyll that turns otherwise green leaves variegated. Chlorophyll is not just what gives plants their green colour. It also essentially turns leaves into solar panels. Green leaves absorb light, producing oxygen and glucose. Our plants use the glucose to fuel growth (also the reason variegated plants grow slower than their all-green counterparts).

When the conditions aren't right for a variegated plant or when a plant's dealing with stress, it's those weaker variegated areas that will show the signs first that's something's wrong by browning. Think of variegated leaves like a canary in a coal mine. Those variegated leaves are more sensitive and alerting you early that something's wrong. The sooner you find and fix the reason, the better. 

Highly variegated 'half-moon' leaves on my Philodendron Pink Princess above (and yes, that newest leaf top right was full pink!)

Stress

The first and most common time a variegated plant will start turning brown is when you first bring it home. That's because moving house is top of the list of 'Most Stressful Life Events' if you're a plant. To be fair, it's way up there for us too. For people, the top 5 most stressful life events are death, major illness or injury, divorce, losing your job and (you guessed it), moving house. Since variegated plants are generally more sensitive than their all-green cousins, they cope worse with moving.

When you first bring a new plant home, your plant has to adjust to what are often multiple changes all at once to the conditions they grew up in. A close second as far as stressful life events for a plant, is repotting. Imagine repotting like moving house for the roots. 
 

Plant stress is typically classed as either abiotic or biotic. Working out exactly what is causing your plant stress is the first step towards stopping the browning getting worse, and preventing it in the future.

Abiotic stress includes stress from environmental factors. Things like heat or cold shock, a sudden change in light, too much or not enough water and too much or too little of other nutrients like nitrogen. Biotic stress comes from biological factors. Things like pests, viruses, bacteria and fungi. 

The solution? Check you're giving the plant the best conditions you can (run through the list below), and the browning should slow down and stop as your plant settles in and adjusts to its new conditions at your place. 

When light causes brown or scorched leaves

The more variegated the leaf, the more it needs our help to photosynthesize

Variegated plants in general tend to be less tolerant of low light than all-green plants. As a general rule, I like to give mine a spot that offers what I call 'bright shade'. Essentially the brightest light possible, but not to the point of direct sunlight hitting those sensitive leaves, which can cause browning and scorching to the more sensitive variegated sections of the leaf.

Browning can happen both from direct sun and from heat, which is why leaves can scorch and look burned even when not in direct sun.

At the other end of the scale, not enough light (or not enough hours of good light), can also cause browning. If that's the cause, the browning happens because there simply isn't enough light to supply what the plant needs to survive, so it starts to essentially 'kill off' excess leaves until it gets to a level of foliage it can maintain with the light level. Of course the first to go are the weaker (variegated) leaves which don't contribute their fair share towards photosynthesis.

This is a cause I often see in Ficus in particular, variegated or otherwise, where they sometimes quite dramatically drop leaves until they get down to a number of leaves the plant can sustain. 

TIP: Abaxial leaf colouration

This is why variegated plants with red leaf backs have different light requirements

If your variegated plant has reddish or purplish leaf backs, like Stromanthe and a lot of the Maranta and Calathea family, some immature Aroids and others, that's a sign they don't need as high light levels and are more sensitive to scorching and browning from too much light.

Called abaxial leaf colouration, those reddish or purplish backs of the leaves is an adaptation to growing in lower-light areas in the wild (such as under a dense, more shaded rainforest canopy or way down on the shady rainforest floor).

That's also the reason you sometimes see it only when climbers are younger such as some aroids. But once they start to get bigger and climb higher up in the canopy they reach areas with more light and have larger leaves, so no longer need the boost the red leaf backs give them to absorb more light.

So when it comes to light, do your research. Check what your plant's ideal light levels are. Then add a little more to allow for their variegated leaves not being able to photosynthesize at full capacity.

Don't be scared of grow lights

Personally, I'm low on 'bright shade' spots at my place, so grow lights have been essential to keeping my variegated plants happy and help prevent browning. Some hobbyists have shared concerns with me over using grow lights for fear of burning the more sensitive variegated foliage. I've found the right choice of light, with grow lights kept at the right distance, means chances are actually LOWER of grow lights burning variegated leaves compared to the higher chance of natural light scorching them.

I either use a Sansi bulb in a desk lamp or floor lamp when I want to boost light for bigger areas (Sansi are also available here on Amazon for those not in New Zealand). Or when I want to boost light levels for just one or a handful of plants, or just a shelf or two of plants, my new favourites are the PHOTO+ grow lights actually made for sensitive and variegated plants.

Over-watering causing browning

Variegated plants are also more sensitive when it comes to watering. In general, variegated plants tend to be more sensitive to over-watering than under-watering, also making them more prone to the dreaded root rot.

Some plants - like the Monstera Thai Constellation - are known for being genetically more prone to root rot. I swear sometimes you can just look at your Thai Constellation wrong while holding a water jug and the roots start rotting. 

By the way, since we're on the topic and this is a common myth, over-watering does NOT mean too much water. You absolutely should water heavily enough so water pours out the drainage holes and all the substrate is evenly wet throughout the pot. Otherwise you can end up with dry rot, where some roots miss out, dry out, then the root hairs die, and next time you water, they rot. Yes, under-watering causes root rot also.

Over-watering means watering again too soon, before the substrate's had time to properly dry out so the roots get the right balance of water and air. It's actually the lack of air that's the usual culprit for root rot. 

In green plants, one of the most obvious signs of over-watering is yellowing in lower leaves first, a sign root rot is going on below the surface. Yellowing can progress to browning if not caught in time. In variegated plants however, they can go straight to browning, often followed by limp, soft, drooping foliage. Some skip this stage and jump straight into dropping lower leaves (such as Ficus).  

Under-watering causing brown leaves

Under-watering is not just when you leave your plant dry for too long, it can also cause problems when you water too lightly and some roots miss out.

Early signs of browning caused by under-watering tends to show up as the leaf tips and edges of the leaves turning brown, especially in the variegated sections. This happens because your plant is 'sucking' the moisture it can't get from its roots, out of the leaves instead. 

Both watering sooner (before the roots dry out), and watering more thoroughly when you do water (so the entire substrate and all roots get thoroughly saturated), will both help prevent this type of browning.

However, the damage will be done, and the leaf won't heal itself, so once you've fixed the problem, by all means trim off those brown sections if they bother you.

Premature browning caused by calcium 

There's a lot of attention given to nitrogen, phosphorus and potassium, the three primary macronutrients our plants need the most of that we give them when we fertilise. But sitting in fourth place, high up on the list of essential minerals our plants need, is a nutrient missing from most fertilisers: calcium.  

Calcium-deficient roots turn black and rot, making calcium a hidden cause of root rot that gets blamed on over-watering. But when it comes to browning in variegated foliage, a lack of calcium may also be to blame.

New tissue needs calcium to form strong cell walls. A calcium deficiency can show as new growth browning prematurely, usually in the weaker or variegated areas first. A calcium deficiency also causes leaf tips to go brown. You might also see brown spots that start on the margins and eventually join in the centre, usually with yellow edges. Another symptoms is jelly-like browning starting at the leaf tips, turning the leaves to a brown mush.

If your fertiliser doesn't include calcium (most don't), an immediate fix before it gets worse is a little dolomite lime or a calcium supplement like CalSi+ added to the soil, then watered in.

Or for those not in New Zealand, look for products made to boost calcium in tomatoes, as a lack of calcium causes browning and rot in tomatoes too, like Bloom City Cal-Mag available on Amazon.

Personally I'd change fertilisers if you have variegated plants and find out your fertiliser doesn't include calcium. Look for one with calcium, ideally listed up high around the fourth position in the guaranteed analysis to make sure you're giving your variegated plants enough. I've listed a couple of my favourite fertilisers for variegated plants further down in this guide. 

Getting the substrate right for variegated plants

(and why you might need to repot ASAP to save your variegated plant from browning)

Substrate that holds a lot of water can be a BIG problem for variegated plants. As the variegated leaves have less ability to photosynthesize at the level that an all-green leaf would, and since photosynthesis is the driver for growth in plants, that means variegated plants tend to grow slower. Slower growth means they use up the water in their substrate slower also. For example, even in the exact same substrate and conditions, you'll find you typically water your Monstera Albo or Thai Constellation far less often than your all-green Monstera Deliciosa. 

If your variegated plant came to you in a peat or soil-based mix, and it's staying wet longer than normal, you may need to consider repotting (and soon)

That finer substrate with high water-holding capacity might have been perfect for the grower or nursery with their very bright, temperature-controlled conditions with good airflow. In their conditions, soil dries out super fast. But take their soil and put it in the typical conditions in our homes and it can be a recipe for root rot. 

A finer substrate that holds more water than air creates an imbalance ideal for root rot, which is caused by fungus and bacteria that love a moist, low-oxygen environment. If you suspect root rot might be the cause of those browning leaves, slide your plant out and check the roots without delay. 

Personally, if the substrate's a concern and browning has started, I'll repot right away, even in winter. I just pop a heat mat under my variegated plants when I repot in winter to keep the roots warm so they recover as if it's summer. I like the Inkbird brand, but if you're not in NZ have a look at the Vivosun Heat Mat available on Amazon.

Spreading brown patches from edema

Spreading translucent or brown patches on variegated leaves can also be due to edema, and an early sign you might need to adjust your conditions. If caught early, edema can be reversed. If it keeps happening or conditions aren't improved, the damage can be permanent. The patches normally start out translucent, which is harder to spot on paler variegated areas of the leaf, until they start going brown.

Edema happens when roots take up water faster than the plant can 'breathe' it out through transpiration. The excess water builds up and with nowhere to go, causes cells in the leaf to swell and eventually burst, giving the leaf a water-soaked appearance. 

Because edema usually happens after watering, over-watering often gets wrongly blamed. You likely haven't over-watered. Edema is a sign you need to give transpiration a boost. There are a few ways you can do that. Increased airflow is one. So is more hours of good light, or better quality of light.

Another way you can help is to check your plant's not being subjected to swings in temperature, or to the cold. What 'too cold' is depends on your plant's preferred zone. I find it more likely to happen when I water later in the day also, likely due to the drop in both temperature and reduced transpiration overnight, so look at watering earlier in the day also to help.

Fertiliser and water causing brown leaf tips and margins in variegated plants

Another cause of brown leaf tips and leaf edges can be fertiliser burn or salt burn. The salts in fertilisers and from the minerals in tap water can build up over time. This tends to happen faster in variegated plants because they don't grow as fast, meaning they don't use up the minerals in their fertiliser as fast, or need as much. Most variegated plants don't need fertilising at the same level as their faster-growing all-green cousins. This can make them more sensitive to what you feed and also to your water source.

Both hard water and bore water (both are higher in minerals), and soft water (which has salt added), can cause the same symptoms as fertiliser burn. An early sign salts are building up is a white crusty layer on the top of the soil or around the drainage holes. Similar to limescale on your kettle or jug, or around your shower and basin or sink.

Don't water through that salty layer! That just dissolves the salts and exposes the roots to being burned. It's best to scrape that layer off or remove the top layer of the soil and replace with fresh substrate.

If your plant is overdue repotting (best done yearly for indoor plants), then take it as a sign to repot now, as those excess salts could be right through the substrate, not just on the surface. It's more likely to be on the surface and around drainage holes because water evaporates but salts don't (the same reason salt flats form)

Excess salts will eventually burn and kill the roots and change the pH of your soil, which can happen before you see the more obvious signs of fertiliser and salt burn above the surface of brown leaf tips and margins.  

Can humidity cause browning?

The short answer is yes, humidity is definitely a factor. Just like not watering often enough, low humidity can cause leaves to brown from leaf tips and edges inwards. A common one in thinner-leafed variegated plants in particular like Stromanthe and Calathea.

I wouldn't recommend misting as a solution to increase humidity however. It barely raises humidity, and not for long enough to make a difference. Plus water sitting on leaves can cause other issues. My go-to are the cordless H2O humidifiers (the 750 model is my favourite).

What's the best fertiliser for variegated plants?

Bring more salt-sensitive and slower growing, I like using a complete and balanced fertiliser so I don't over-do any particular mineral. I also opt for a reduced-salt fertiliser for my variegated plants. My go-to is GT (Growth Technology), which is complete and balanced, and guarantees no sodium or chlorides (two of the highest-salt-index ingredients in most fertilisers).

GT is also free of urea, the most common nitrogen source used in most fertilisers. Instead they use a nitrogen source that's easier for indoor plants to absorb so excess doesn't end up sitting in the soil. GT is also pH-buffered to help keep soil pH at the level that avoids minerals becoming toxic and burning roots. 

I also like how much control I have over changing the dose for my slower-growing more sensitive variegated plants. Some fertiliser are so strong that even a tiny bit over risks fertiliser burn. GT at the general maintenance level is 5mls per 1 litre water, but for my variegated plants and other salt-sensitive and slower growers, I use it at 3mls per 1 litre water, every time I water (called the weekly weakly method >).

If you read the section on calcium earlier in this guide, you'll already know why you want your fertiliser to include calcium. GT is one of the few that does include calcium, and it's nice and high up at the fourth ingredient listed in the guaranteed analysis, right where variegated plants need it. 

GT has a big range but my go-to for my variegated foliage plants is GT Foliage Focus, or for my variegated plants that flower (like my variegated African Violets and Peace Lilies), GT Complete Focus is superb too. And yes, for those not in New Zealand, you can now get GT fertilisers on Amazon.

How does silica reduce browning in variegated plants?

Actually, silica is recommended for all plants, so that's not something unique to our variegated indoor plants. But silica is associated with variegated plants in particular because it helps protect from browning.

Before you get all excited, keep in mind (like calcium), silica won't fix existing browning. Also, like calcium, silica isn't a mobile nutrient. That's why both calcium and silica should be given frequently (I do it every time I water), so that a deficiency doesn't cause browning in the first place. 

Silica works in a similar way to calcium in that it strengthens plants. But unlike calcium, a deficiency in silica doesn't directly cause browning. And unlike calcium, silica is not essential, only beneficial. Outdoors, soil water is often abundant in silica. It's really only our indoor plants that silica should be considered essential for, since they miss out.

Silica's is nicknamed 'Nature's Bodyguard' because of strengthens and protects plants. It doesn't just make plants physically stronger, but also helps plants cope with both abiotic and biotic stress that we covered earlier. By making plants stronger, silica helps protect weaker areas from browning in reaction to the long list of stress factors this guide covers. 

There are a lot of silica supplements for plants on the market, but my go-to is GT Silica because it plays nicely with my GT Focus fertilisers. Silica doesn't always mix well with others because it's more alkaline. When used with GT Focus fertilisers however, you can mix-feed so your variegated plants get both silica, calcium and all their other essentials, every time you water. 

What about a fully variegated leaf?

Even if you do everything right, the bad news is a fully-variegated leaf is usually too weak to survive for long. There are exceptions, my waxy-leafed hoyas for example like my Carnosa, but most fully-variegated leaves such as all-white or all-pink will end up browning and dying early. 

And no, this isn't a list of absolutely every cause of browning in variegated plants (we barely touched on biotic stress like bugs), but I hope one or more of these tips and tricks put an end to browning for your variegated plants or help you avoid it in the first place.

Keep learning...

Find out what edema is, why it causes leaves to turn transparent and how to fix it >