All About: Watering!
Watering.
It's most of how you interact with your plants! Obviously, it's super important... but watering issues are also the single most common way that people kill their beloved plants!
So what gives? How do you avoid overwatering or underwatering your plants, and give them what they need?
I want to say it's simple -- and it is, eventually, once you get the hang of it! In this article, I'll go over what you need to do to properly water any houseplant... with a bit of research, of course. (Note: there are a LOT of different schools of thought as far as watering; I'll try to give an overview of all of them, but I, of course, only use one myself, so your mileage may vary a little!)
In this article:
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Factors That Affect Watering
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Watering Frequency
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Overwatering vs Underwatering
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Kinds of Water
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Bottom Watering vs Top Watering
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Drainage Holes and How Much to Water
Factors that Affect Watering
There are an incredible number of factors that affect how often you need to water each individual plant, including (but not limited to):
Plant Species
Different species have different watering needs -- one of the first things that you should learn about each and every plant, along with the lighting requirements, is what the watering needs of that plant species are! This could range from wanting to be kept consistently moist to wanting the soil to dry out completely between waterings.
Lighting
How much light you give your plant will determine how much water it needs, to some extent -- a plant in a highly-lit spot will drink more water, since it needs it to process the energy. This means that if you're having trouble keeping up with watering needs, you can move it to a different spot with different lighting to change them -- but it also means that if you move it to a different spot for any reason, the watering needs could change!
Soil Mix
The composition of your soil mixture will affect how well it retains moisture, as well as how quickly water evaporates from it -- the more air pockets in the soil mix, the more evaporation can take place!
Humidity
Humidity doesn't just affect the plant directly -- it also affects its watering! The majority of water leaving each pot isn't taken up by the plant -- it's actually evaporated. Humidity plays into this because humid air can't hold as much water as dry air -- so if your environment is particularly humid, you'll need to water less.
AIrflow
As mentioned above, most water loss is due to evaporation -- and one way to increase evaporation is to increase airflow (usually by adding a fan in the room somewhere)! What this does is make sure that when water evaporates from the soil, that water-laden air gets moved away and is replaced with (theoretically) drier air! Airflow is completely overlooked when it comes to houseplants, but I personally suggest always having a fan on in the room to help prevent overwatering.
Roots
If a plant is particularly root-bound, there isn't much soil left to hold water! This will mean that you'll need to water more frequently (and that you should really repot).
Temperature
A hot day will mean more evaporation, since warm air can hold more moisture than cool air!
Pot Material
Plastic or ceramic pots keep water in, but terracotta (or other porous, less common materials like concrete) will wick moisture away through the pot itself, leading to more frequent watering!
Watering Frequency
So, the big question: how often should you water your plant?
Well... the answer is a little complicated.
It would be wonderful if you could water on a set calendar schedule -- say watering your pothos every Sunday, all year long -- but if you think about the list of factors that affect how often you need to water... a lot of them change over time! Lighting waxes and wanes over the course of the year, you might move it to a new spot with entirely new lighting/humidity, the roots grow in the pot and there's less soil there, you might repot it completely... So at the same time, how often it needs to be watered will change over time!
The single best piece of advice I could give any plant parent is to learn to water based on the plant, not on the calendar.
What this looks like can take a couple forms!
The easiest and simplest way to check if a plant needs watering: stick your finger in it! If dirt clings to your finger when you pull it out, then it's still wet to that depth, and you can judge from there whether that species of plant needs to be watered or dry out some more!
(Note: Don't shell out the money for a fancy water meter -- they can be unreliable, and honestly your finger works just as well! If you really can't stand the feeling of dirt, then use a clean chopstick -- the same rules apply!)
The fastest method to check if a plant needs watering is to pick it up -- believe it or not, this is the method that most waterers at garden centres will use, and it's frighteningly accurate, particularly for smaller plants in plastic pots. Plants aren't generally that heavy on their own when they're small -- and dry soil, in small pots, is pretty light as well! Water, however, is heavy. So if you pick it up, and it's heavy -- it has a decent amount of water in it!
Pick up your plants every time that you water them, and compare how heavy they are before and after watering -- you'll learn the difference over time, and that'll be the quickest way to water your plants!
As well, you can often tell if certain plants need watering in more specific ways! Often, plants will droop or sag a little bit if they're thirsty, and some plants like peace lilies or fittonia will "faint" or "play dead" -- ideally, you should be watering before it hits that point, but if you're unsure about watering still for that plant, that can be a cue!
There are three more specific ways to check for some plants that we can share:
First, for hoyas, there's something called the taco test -- find a mature leaf, close to the soil, and gently try to fold it up like a little taco (hotdog-style, not hamburger-style). If it resists, don't force it -- you can easily snap a leaf in half that way! That means that it doesn't need any water, anyway. If it bends easily, with no resistance, give that baby a drink!
Second, for snake plants: similarly, try gently bending one of the mature leaves! It should resist your attempts to bend it (though generally it's still fairly pliable). If it bends super easily, and feels paper thin, then it's time for a water!
Third, for many succulents, including the jade plant, string of hearts/pearls/etc, or any plant that is thick and fleshy -- try gently squeezing the leaf! If it's thick and plump, then you don't need to water it -- but if it feels paper-thin, then that baby needs some water!
(The underlying principle is the same for all three, by the way -- the water is stored in the leaves, and that's what's changing!)
Overwatering vs Underwatering
If there's a choice between overwatering and underwatering?
Always choose to underwater.
Pretty much every single plant out there will bounce back from being underwatered far easier than it'll bounce back from being overwatered -- and here's why!
To understand, first you need to know what each term means, and why it can spell doom for your wonderful little plants! Overwatering isn't, strictly, actually about having too much water in the soil -- but instead, it's about having not enough oxygen in the soil. Roots need oxygen to operate properly, and there are anaerobic bacteria that cause root rot that thrive where there's no oxygen as well. Underwatering is exactly what it sounds like, though -- not having enough water! Water is truly the lifeforce of all living things, and it's the most important thing for plants; without it, they will shrivel up, brown, and die... some plants faster and more dramatically than others.
Overwatering can cause a plant's demise in two different ways. First, it can kill off the roots due to a lack of oxygen; ironically, this ends up making the plant die of thirst, because the roots can't take up enough water! The more common -- and more deadly -- issue, however, is root rot.
Root rot is, to some extent, exactly what it sounds like -- your roots are rotting! Instead of firm, light brown or white roots, you'll find weak, flimsy, dark brown or black roots, and you'll be able to smell the rot. This is caused by that anaerobic bacteria that was mentioned above -- bacteria that specifically thrives in low- or no-oxygen environments, such as a pot of waterlogged soil. Once it gets a hold, it's often hard to get rid of -- often requiring cutting away affected roots manually!
Meanwhile,underwatering just results in a slow, steady death -- the plant will slowly shrivel away, leaving lots of time for water to revive it! You'll often still see some leaf loss -- especially with certain plants like Ficus triangularis -- but the bulk of the plant will survive!
So: if you aren't sure about when to water, err on the side of underwatering!
Kinds of Water
There's a lot of talk online about the right kind of water to use when watering your plants! There are a surprising number of types of water, in fact, each with different qualities, upsides, and downsides.
Tap Water
Upsides: Obviously, super easy to get and generally the cheapest option. Generally a good option!
Downsides: Tap water is generally chlorinated to make it safe for human consumption, which can in some cases cause damage to specific sensitive plants, and only sometimes. I can't stress enough that this is a rare occurrence, and most of the time when people think that it's the culprit, it's actually low humidity.
Note: You used to be able to just leave water out to "off-gas" the chlorine -- and you still can... maybe, depending on where you live. Most places now use chloramine instead of chlorine, which doesn't off-gas. If you're worried, use a dechlorinator made for fish tanks!
Rainwater
Upsides: It's as nature intended! Generally free of harmful chemicals and heavy minerals. Plus, depending on where you are and how you collect it, it's free!
Downsides: It's just really annoying to collect, honestly, and in my opinion flat-out not worth it. Timing is erratic and uncontrollable, it's hard to guarantee you'll have the amount you need... so much is out of your control.
Distilled/Reverse Osmosis Water
Upsides: These are very similar types of water -- both are by nature very pure, free of any pollutants.
Downsides: Plants actually do get some necessary nutrients from water! Watering entirely with distilled water will require that you re-mineralize it occasionally, or use a comprehensive fertilizer with micro-nutrients.
Note: Only ever use distilled/RO water to water carnivorous plants! They're very sensitive to nutrients and minerals, because of how they evolved, so this is one case where you want only distilled/RO!
Fish Tank Water
Upsides: Honestly, probably the best option overall! Nitrates (the reason you need to do regular water changes) are a perfect source of nitrogen, fish waste provides all sorts of other nutrients, and if you're fertilizing your fish tank plants, some of that will still be in the water as well -- plus, it's dechlorinated and heavy metals are removed with the water conditioner, so no need to worry about sensitive plants. You're also re-using water, which is always a plus.
Plus, fishy friends!
Downsides: You need to keep up at least one fish tank, and if you have a large collection, you may need either a fairly large one, or multiple tanks -- and that's a whole other world to explore! Plus, to get the water to water your plants, you need to do a water change, then collect that water so you have it on hand; it's a decent amount of extra work.
(But.. fishy friends!)
Overall Winner:
Definitely fish tank water, in my mind (and in my home -- I have three tanks to provide the water)! It's naturally-fertilized, so you don't need to add extra fertilizer to your water -- and sensitive plants are fine with it!
Bottom Watering vs Top Watering
Bottom watering is one of the most common suggestions you'll encounter online -- but what is it, and is it actually as helpful as everyone claims?
Bottom watering (or, hilariously, "butt chugging") is where you place a pot with drainage holes into a larger container that has water in it, and leave it for a while -- generally about 10-15 minutes. Because of capillary action, the water gets drawn up into the soil. Once the top is moist to the touch, you remove the pot, since the soil is equally and thoroughly saturated.
It's often suggested for specific plants with leaves that are prone to rot or discolouration if there's standing water on them -- such as African Violets -- because there's no chance of water getting on the leaves, but it's also often treated as a panacea/cure-all for any watering issues. (If you DO get water on the leaves while watering, you can easily just sit it in front of a fan for a few minutes! That'll resolve any issues, generally.)
It can be helpful, for sure -- but it's not going to be the be-all-end-all.
The main reason that bottom watering can definitely be helpful: it makes sure that the soil is thoroughly saturated every time you water. This means that you're not only watering part of the root system, you're far less likely to underwater, and because you're not adding extra water after saturation, you're less likely to overwater. (It's still definitely possible -- but a bit harder.)
The biggest downside to bottom watering is just the process and time involved in doing so -- a lot of people with large plants (or large plant collections) will use their bathtub as the bottom receptacle for the pots to sit in, but even still, you need to wait at least 10-15 minutes with each round of pots, and if you have a large plant collection, that time adds up -- whereas, with top watering, I can water my roughly 100 plants in about 15 minutes instead.
There isn't any inherent disadvantage or reason not to bottom water. If that's your preferred method, you do you! Just know that it's not going to cure every problem you have, despite what's written online!
Drainage Holes and How Much to Water
You'll notice that nursery pots -- the drab-coloured, thin plastic pots that you'll buy most plants in -- have excellent, large drainage holes at the bottom for excess water to flow out of. Some decorative pots do, as well, but most of them -- particularly ceramic ones -- don't.
What gives?
Well -- depending on the method of watering you use, drainage holes can either be completely necessary, or they can be helpful but not strictly necessary.
There is no downside to having drainage holes at the bottom of a pot, ever!
No matter how you water, having the ability for excess water to easily escape is never a bad thing. If you don't have drainage holes, you do need to be pretty careful about watering, to make sure that that excess water doesn't sit at the bottom of your pot, since that can easily cause root rot and the death of your plant! This means that, for pots that have no drainage holes, the best way to water is to give smaller amounts more frequently. Depending on the plant's needs, this could mean just a splash now and then, or it could mean more -- you'll find your rhythm, but when there are no drainage holes err even more on the side of underwatering! If you're not sure how much water to give your plant, give it less than you think.
You may see posts online about "small amounts more frequently" being a bad way to water, with any number of claims about what it does to the soil; thorough research hasn't turned up a true claim that we've seen so far! The most common claim is that you won't soak your soil all the way down, but if you use a clear pot, you can very quickly prove this false; soil lets water move through it pretty effectively. If small amounts more frequently is the method that works for you, then do it!
But what if that doesn't work for you? What if you want to bottom water, or if your usual method of watering is to soak each plant until water drains from the drainage holes?
If you still want to use cute decorative pots, then there are two things you can do!
First, and easiest, is to only use the decorative pot as a cache pot -- meaning that you keep your plant in the nursery pot, but just hide it inside the decorative pot! This lets you keep the cute pots -- and even enables changing them up easily! -- without losing drainage. It's probably the best method, in fact! The only problem is that some pots are weirdly-shaped, and those can make cache pots difficult or impossible to use, but with some creative cutting, most decorative pots are usable!
Secondly, if you're brave, you can drill your own drainage holes! For ceramic pots, you'll need to purchase a diamond-tipped drill bit. Make sure to have water on the pot as you're drilling -- it helps cool down the ceramic, leading to fewer breaks -- and be ready to lose pots every once in a while, as sometimes they'll crack no matter what you do!
As a final note, and this can't be stressed enough:
Do not, under any circumstances, put rocks (or anything else) at the bottom of your pot to "increase drainage"!
Not only does it not increase drainage -- despite the fact that it seems like it should -- but it actually makes it easier to overwater by reducing the amount of available soil in the pot and raising the effective water table!
Basically, there is no "excess" water to drain until the soil is saturated, so even though there are pockets of air underneath the soil for water to drain into... it doesn't drain until the soil above it is already saturated, which endangers any roots that are sitting in waterlogged soil!
It seems backwards, but it's true! If you've already done this, you don't need to go repot everything right away to remove them by any means -- just remove them the next time you repot!