Monstera Thai Constellation - The Ultimate Care Guide (and how not to kill them)
The rather dramatic price drop for Monstera Thai Constellation recently has meant many of us have been lucky enough to tick this holy grail off our wish-list. And no, care for the Thai Constellation is definitely NOT the same as their all-green Monstera cousins, but if you do have a Monstera Deliciosa that's thriving, you'll find the Thai Constellation does share a few similarities. But it's the differences you need to watch out for...
Easy, but not easy peasy
The good news is Monstera Thai Constellation are surprisingly easy care with a few simple considerations. Well, simple once you know them better. It's also scarily easy to kill them with kindness, or what you think is the right thing to do, especially if you haven't owned a Monstera at all before, and especially in the first few weeks after bringing them home.
Unlike their all-green Monstera buddies, Thai Constellation are less tolerant of drying out, are slower growing, as well as more sensitive to light, temperature, humidity and fertiliser. But they do share some common care requirements too. My big boy Monstera Deliciosa is called Frank (short for Frankenstein - Monstera... Monster... Frankenstein? You get it). So if you have your own Frank you've kept happy, you're way ahead already.
Can you make Thai Constellation more variegated?
Unlike the more sectoral variegation (a fancy way of saying 'big sections'), of the Albo, the Thai Constellation has more speckled and flecked variegation, and thankfully, has stable variegation (and no, the Albo doesn't).
That means your Thai Constellation will keep that gorgeous variegation. Bonus?What one leaf does, won't change what the next leaf does (not so with the Albo). Your Thai will not revert to fully green leaves! Believe me, the Thai really wants to be variegated.
The Thai's variegation is also more a creamy, yellowy-white than the Albo's brighter white, so does have a definite creamy-yellow tinge to the white. More light helps it whiten and older leaves can lighten up over time too.
Some are more yellow than others, like these below from Costa Farm's controversial announcement that they would have Thai Constellation in 2022 which got everyone excited there would be a massive price drop (spoiler alert: it never happened).
You absolutely can still get those lovely big sectoral patches on a Thai, like the Albo. Plus just because your Thai arrived with no big variegated patches does not mean it won't get them, as the variegation is in the cells, not dependent on the stem like the Albo.
From my own experience, I've found baby Thai leaves are more freckled and speckled, and as the leaves mature you get larger, cleaner areas of variegation and more 'spread out' less dominant speckling.
What's the best potting mix for Thai Constellation?
Light, light, light. Not sunlight. I'm talking light, free-draining soil. Do not make the mistake of planting your Thai in straight potting mix. That's a big no no. Way too dense. Talk about how to invite root rot!
I personally take the guesswork out of the right potting mix, and a use a pre-made aroid mix for mine. The one I use is a combo of orchid bark, fern fibre, pumice, horticultural charcoal and more. No peat. No soil. No slow-release fertiliser (more coming up about fertiliser). For those in New Zealand, the one I use is called Bio Leaf Aroid Medium Blend. I start smaller Thai's in that mix, and the bigger boys go in the Bio Leaf Variegated Aroid Chunky Blend.
However you definitely can DIY your own mix. Just keep in mind you want plenty of air space for the roots, and free draining mediums. Nothing too fine, dense or compact. For free-draining substrates think orchid mix, succulent mix, bark, perlite, fern fibre, pumice, you get the idea. Personally I prefer a soil-less mix for mine, but if your conditions are very dry you might want to add some potting soil to your mix to increase the water-holding capacity (even then, I'd still stick to about 20% max of potting soil).
No drainage layer!
Don't fall for the myth of adding a 'drainage layer' to the bottom of the pot below the soil. I used to do that too. Turns out it creates a perched water table which actually INCREASES water-retention, moving the water layer up closer to the roots! Adding a drainage layer increases the risk of root rot (here's why if you're curious about the science).
Instead, you want to use a well-blended, free-draining mix right the way down. To avoid soil coming out the drainage holes, you can use potting mesh if you like (if you're looking for that overseas, you want drainage mesh like this), but keep in mind it's usually only the first or second water that will have some fine material from the mix wash out. After that, a good chunky aroid mix shouldn't have anything wash out when you water.
How and when to repot a Monstera Thai Constellation
When it comes time to repot, don't. Just kidding (sort-of). Repot if you really have to, especially if the substrate is staying wet too long (in which case I'd be in there right away). Unless there's good reason though, it's best not to repot your new arrival too soon. Rookie mistake I think we've all made. Adjusting to a new environment is enough to deal with as it is before putting a plant through the stress of repotting on top of transport stress (I normally wait about a month unless there's a health reason for a repot).
One reason I would repot right away is poor soil. If your Thai's not in suitable soil, something that's staying wet too long, I'd repot pretty soon. Watch for signs of root rot caused by water retention. Often the mix that's great for commercial nurseries and growers is no good in typical household conditions. You don't have to pot up a size, just get rid of that soil and give him a better mix more suited to your conditions, back in to the same pot is fine.
PRO TIP: Before re-using a pot, give it a clean with hydrogen peroxide (for those in NZ), to help kill any bugs, fungi or bacteria that might be hiding, including the fungus that causes root rot. For my international plant friends you want to look for 3% hydrogen peroxide (like this Essential Oxygen 3%).
When you do pot up, only go up about one inch in pot size, or a couple of cms (from a 14cm to a 16cm wide pot for example). Too massive an increase can (at best) stop or slow stem and leaf growth while your plant diverts its energy in to root growth, to fill up all that new room - or (much worse), lead to root rot from that big increase in soil holding far more water than the roots are used to coping with. If and when you do repot, use the tips in the Guide to Repotting to cause minimal stress and a faster recovery without complications.
Back. Away. From. The. Water.
The Monstera Thai Constellation is 100% NOT the plant for you if you're an over-waterer. No helicopter parenting needed here. Time to change your watering ways. Think lightly moist, not wet.
Over-watering is far worse than under-watering for the Thai. Root rot is your enemy (and unfortunately Thai are more prone to root rot). BUT they aren't as tolerant of drying out like their green Monstera Deliciosa cousins either, so you need to find the right balance.
I'd wait till about half to 3/4 of the potting mix is dry before watering again. Don't let them fully dry out. If you're worried, a cheap water meter helps with peace of mind as you can push the probes down to check below the surface easily. If you're not in New Zealand, you can get the same ones here.
But if budget allows, consider grabbing a Sustee in New Zealand, or here's Sustee on Amazon too for my international plant friends, or a Crew Soil Sensor. Sustee are the type you can leave in your plant and tell at a glance what the moisture level is down at root level as they change colour as the substrate dries out. Total game changer. A cheap investment for not stuffing up such an important element of care for these chaps.
The right pot
You could go for terracotta depending on how diligent you are at watering. If you err on the side of neglect and are more of an under-waterer, stay away from terracotta as your plants will dry out too fast. Terracotta is a goodie for over-waterers though!
Personally I go for stock-standard, plastic nursery pots with drainage holes, popped neatly inside a cover pot. I much prefer clear pots or for those overseas, have a look for orchid pots, as you can see the water droplets form lower and lower on the inside of the pot and know when to water. I never water while in the cover pot, but you can. If you do, set a timer and tip out excess water after 10 to 15 minutes. Don't let your Thai sit or soak in water for long.
Thai have a deep root system, so a deeper / taller pot is a better choice than a wider / shallower pot for these guys. Whatever you choose, something with drainage holes is an absolute MUST in my books. The risk of root rot is just too high without drainage otherwise.
Although they can tolerate cooler and warmer temperatures short-term, aim to keep your Monstera Thai Constellation in his happy range of 20 to 30 degrees. They can tolerate cooler provided all other conditions are good and it's not a sudden temp change, but I still try to avoid dropping below 15 to 18 degrees (celsius).
Luckily that's a temperature range that's not too difficult to achieve in most homes, but do keep an eye on those temperature drops come winter, especially if you got your Thai during easier-care summer months. Vents and draughts are a no for these chaps. Sudden temp changes are also a no. Move them from the path of cool or hot airflow from your aircon or heat pump. Also consider what temperature your Thai's environment is when you're not home, and overnight.
Light is another area the Monstera Thai Constellation differs from their all-green buddies. Variegated plants in general need to work harder to photosynthesize. Yep, that rather important 'vital for life' requirement. Since light is a biggie for photosynthesis, your Thai needs more of it than the all-green Monstera to maintain those variegated leaves, especially ones with bigger variegated sections.
Go for a position with plenty of bright light. Remember the variegated sections lack chlorophyll (otherwise they would be green), which means they can't absorb light and are more photo-sensitive. Low light is not recommended. Better to go for medium to bright light.
Ideally that light should not be only from one direction though, as like their green cousin, they'll reach for the light and can become more leggy and less leafy in low light. If you can't help the stronger light from one direction, quarter turn your Thai about monthly and they should be sweet.
Unlike some highly-variegated plants though, the Thai can handle some direct sunlight. Especially the greener more speckled and freckled leaves without big white patches. Those big white patches though? I'd keep clear of direct sun for fear of sunburn. Dappled, moving light is always better and morning sun or winter sun is better than the more intense afternoon or summer sun.
Stay clear of direct sun all together if unsure, but if the perfect spot for your Thai gets early morning sun in summer, or weaker daytime sun in winter, you should be fine. Just stay out of the sun for longer lengths of time, and no super-harsh daytime and afternoon sun direct in summer. Think gentle sun and you'll be sweet.
Monstera Thai Constellation have similar humidity requirements to their green Monstera Deliciosa fam. I'd call them 'medium' on the humidity scale. In a typical kiwi summer no extra humidity should be needed unless you live in a very dry region. It's plenty humid for our lucky tropical indoor plants in general in NZ.
In winter or if you have a heat pump, DVS, HRV or fireplace going, you may need to consider running a humidifier. Look out for for crispy, dry, brown tips or edges as a sign extra humidity is required. For humidity I find a pebble tray doesn't do much, nor does misting. Aim for humidity above 60%. Get a hygrometer to find out what your level is now, and consider a plant humidifier if you find humidity is too low.
Tip for new arrivals: Thai Monstera typically start out in a lab environment if grown from tissue culture, then often moved to an indoor nursery with plenty of warmth and humidity, so they become used to a higher humidity environment. When you first get yours home, maintaining that warmth and higher humidity, at least for the first couple of weeks, will help your Thai settle in sooner with less stress, so less chance of disease or leaf loss - or those dreaded brown patches!
What's the best fertiliser for Thai Constellation?
Being a slower grower than the all-green Monstera Deliciosa, the Thai rates at the lighter end of a medium to light feeder. However that doesn't mean you should starve them! Definitely do feed your Thai, just go easy. You don't want to risk fertiliser burn for the Thai even more than most as being slower-growers that are more salt-sensitive. The Weakly Weekly method is ideal.
Look for a fertiliser that's complete and balanced, and one that ideally avoids ingredients with a higher salt index. There's a section on fertiliser in the Variegated Indoor Plant Care guide that gives you a few options of fertilisers that are safer for variegated plants. The one I use is free of urea, chlorides and sodium, but if yours does have those more common fertiliser ingredients, a good heavy top water about once a month to flush out excess salts is important.
What I would say, no matter what food you choose, is best not to go overboard on the DIY fertiliser. How well your Thai will grow depends on what nutrient it has the least of, not the most. Not enough of a micro-nutrient can lead to excess of a macro-nutrient. It's too easy to overdose on one nutrient when you make your own.
By all means experiment on your cheaper jungle members, and your Thai if you really want to, but for me the price tag on a Monstera Thai Constellation puts it firmly on my non-guinea-pig list. No banana skins, eggshells, milk-watering, tea, coffee grounds... (the list goes on).
Monstera Thai Constellation Pro Tips & Problem Solving
Translucent changing to brown patches, only on highly-variegated or white areas
Something like this:
This one can be a bit upsetting as it may mean you'll lose that leaf, depending how bad the browning is, and how fast it gets worse. It certainly won't 'heal' itself. The upside is it's unusual to lose the whole plant. You may however lose more than one leaf before it comes right.
When your Thai has a lot of highly-variegated leaves (big white sections or a mainly or all-white leaf), it can't support itself like an mainly-green leaf can, which also makes it more sensitive to a change in conditions. Those leaves with big white sections are weaker. They are more delicate, more sensitive, and age faster, so turn brown and die off faster - especially when under stress (such as the move from a warm, humid nursery, to your home). A balance of at least 50/50 green to variegation is a healthier minimum for a leaf to be stable.
When a leaf starts browning like this, you can try cutting off the brown patch (not the green!), or the entire leaf, or leave it as is and hope it doesn't spread. Either way, what you do want to do is make sure conditions are good in general, check that it's not fungal or from overwatering, and that you're not contributing to your plant's stress levels.
This is unfortunately pretty common when you first take any super-variegated plant home, or get it delivered. Remember before it got to you, it likely left its cozy home in the nursery where it has been for some time (often in warm, humid, bright conditions), then got transported to the plant store - and if the store doesn't quarantine - wisked away again, shipped off to you before it can even recover after the trip from the nursery! This is a common concern with other extra-variegated plants like Super White Marble Queen also.
If your Monstera's already under stress, then you do something silly like promptly repot him, you've added transplant stress, on top of transport stress. Ouch. Big time changes for any plant, let alone those weaker extra-variegated leaves. Keep in mind repotting to a plant, is like surgery to us. Big time recovery needed.
What you can do to help, is find one, perfect spot, and leave your Thai to settle in. Don't water too soon. Feed, but not full strength when you do water (I'd start off half-strength). Lots of bright light but no direct sun. No draughts. Trim off those brown patches if you're feeling brave. I've also started adding silicon to my watering routine after reading about other Albo and Thai Constellation owners preventing browning thanks to silicon (so far so good for me).
If your plant's had no recent stress, no change in environment, and it's starting to brown in patches, also check over-watering, fungal disease, pests, sunburn or heat stress.
Why do Thai Constellation leaves turn yellow?
Many things can cause yellowing leaves. The #1 cause is a lack of nutrients. Especially when it's lower-down or older leaves going yellow. What your plant can't get through the roots, it instead starts taking from older leaves, causing them to go yellow as your plant sends those nutrients to sustain newer leaves instead. The first thing to do is find out what nutrient your plant might be missing that's causing those yellow leaves.
It could be a lack of water or too much water. Root hairs can die at both extremes, preventing them from absorbing water properly, and causing them to essentially 'drown' and rot. Kept too dry for too long (not enough water), or kept wet for too long (not enough air), can both damage roots.
Choosing a chunky, free-draining potting mix also helps avoid both under- and over-watering. You want a mix that has plenty of air space, drains easily, but still retains some water and nutrients for slow-release when the plant needs it. See the section above on ideal substrates to use. Water before your substrate is fully dry. Then when you do water, water thoroughly so the entire potting mix is saturated. Use a pot with drainage holes and don't let your plant stay sitting in water.
Another common cause of yellowing leaves is a mineral deficiency such as nitrogen or phosphorus. Grab some fertiliser to help fix that one, but use the Weakly Weekly method so you avoid both fertiliser burn and deficiencies by feeding little and often, every time you water. Look for a fertiliser safe for variegated plants.
Why does my Thai Constellation have brown crispy edges?
In Monstera this is typically due to either light, humidity, food or water. If you think it's light, avoid direct sunlight hitting the leaves (as this can scorch them), and find a spot with the brightest, indirect light possible.
TC are more salt-sensitive than faster growers, so also check your water. If you have particularly hard water (high in chlorine and other minerals), shift to using tap water without chlorine (treat your water with a product like AquaPlus to instantly remove chlorine), or look at other options like rainwater or fish tank water.
Lastly but very importantly, check what you're feeding. TC's grow slower so the Weakly Weekly method is ideal for them. Don't starve them though! If you don't fertilise at all, that can also be a cause of damaged or discoloured leaves. Look for a food suitable for variegated plants.
If you don't know if your food is a low-salt formula suitable for variegated plants, then flush water to flush out excess mineral salts to help avoid fertiliser burn (flush watering s simply a good heavy top water until water flows freely out the drainage holes). Have a read of the fertiliser section in the Variegated Plant Care Guide for more about choosing a safe fertiliser.
You can trim off the brown edges if it's only the very edge as I find it hardens up again, but if it's a bigger section I wouldn't trim entire chunks off as you may end up losing the entire leaf. Up to you based on how bad it is and if it's spreading or not.
Why isn't my Thai Constellation growing?
The Thai can pop out a new leaf every month when it's really humming, or be the snail of the plant world with slow or sometimes no growth. It's not unusual to hear complaints about no growth for months after they move to their new home. Some love life and get growing again pretty fast, but in general a 3 to 6 month 'nothing to see here' hiatus is pretty normal, especially if they move home in cooler months.
Other possible causes of a growth slow-down are not enough light, cooler temperatures and nutrient deficiencies - but if your Thai is otherwise happy and healthy and conditions are good, he's not in too giant a pot and you are feeding (but just lightly - the Weakly Weekly method is ideal), then have patience. You should get new growth when the time is right. Warmth, extra light and higher humidity can all help speed up growth also.
If the whole leaf is going brown one common cause is not enough water, or letting your Thai stay dry too long between watering. Check the soil. Give a good thorough water if needed. When you do water, make sure the substrate is fully saturated. And keep to more consistent watering going forward. Also check the other problems above and below for more possible causes and solutions.
Thai Monstera are particular prone to root rot. Usually caused by overwatering. Too much water, leaves not enough oxygen for roots to breathe. Dense soil can also hold too much water, causing the same problem even when you don't overwater. Free-draining soil is a must.
Roots affected by root rot will be black and mushy. Leaves will typically be limp, wilt and go yellow. Slide your Monstera out of the pot and check the roots. It can quickly spread to infect healthy roots too, so don't delay. Deal with root rot immediately. Treating root rot as soon as possible is essential for your plant's survival.
Sometimes a fungus can be dormant in the soil and cause root rot but it's more likely to be overwatering. Either way, remove your plant from the soil and wash the roots under running water. Using clean, sharp snips, prune off damaged roots. Dispose of the soil and clean the pot (a mild bleach solution will kill any fungus in case that's the cause). Put fresh, well-draining soil in and repot in the same pot (or same size pot).
If you found this guide helpful, you might also like...
Read this guide: The Ultimate Care Guide for Variegated Indoor Plants >
Read this article: What is the Weakly Weekly Method for feeding indoor plants? >
If this article helped you, please consider a share. There's no income from it for me, I just really like to know it might help one more person enjoy their happy, healthy Monstera Thai Constellation :)