Plant Watering Explained: How and When to Water Your Plants
Second only to understanding light levels in the home and how they affect our plants, which you can read more of in our Ultimate Houseplant Lighting Guide, understanding how to water our plants is the most important part of plant care. Now, we know what you might be thinking, why do we need an article about how to water plants, isn't it obvious? But that couldn't be further from the truth because there are plenty of ambiguous instructions out there in the houseplant world when it comes to watering our plants. Don't overwater your plants, don't underwater your plants, keep the soil moist but not wet, this plant is drought-tolerant, that plant is not drought tolerant, etc.
Although it might seem self-explanatory, watering our houseplants can be quite a nuanced process, and we want to clear up any confusion or questions that you may have. In the outdoors, plants are watered when Mother Nature wants to water them, but when they are indoors, the amount of moisture that they receive is completely dependent on you and the environment that you are providing them. This is why there is no one guide fits all for plants, because every home environment is unique - there could be different light levels present, changing humidity levels, air conditioning or central heating could be at play, time of the year will affect watering schedules as well, and the list goes on.
In this article, we discuss everything from how to water your plants, when to water them, what type of water is best, and truly understanding the direct relationship between light levels and watering needs. If you want to know about a certain plant's needs, please see our product pages and individual care guides for more specific care, as this guide will stay rather general. If you want to know more about your plant's needs according to your unique home environment, feel free to reach out to us at help@jomostudio.com for a more tailored response.
Why Plants Need Water
This is simple enough: plants need moisture to perform photosynthesis! Absorbed by the roots in a process called transpiration, water travels through the roots and stems to the leaves where it is lost from the plant due to evaporation in the bright light of day. Water will always go where it is needed most, generally pulled up from the roots, but if the soil and roots are dry, water is taken from the leaves themselves, resulting in a deflated plant (i.e. a thirsty plant).
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Have you ever noticed droplets on the ends of some leaves, on a Monstera leaf, for example? This process is called guttation, where liquid droplets (called xylem sap) form on the tips of perfectly healthy leaves. This sap is non-toxic and will not harm your plants or floors, but it is generally a sign that your plant has a little more moisture than it needs and finds a way to get rid of the excess. It is not necessarily a bad thing, but merely a natural process of life, like sweating, so unless your stems are getting mushy or healthy leaves turn yellow or brown, your plant is just fine.
Water is also important structurally for plants. Plant cells become stiff and help a plant stand upright, due to the water pressure of water flowing through the stems, maintaining the structural shape. When there is a lack of water, the cells become deflated and the plant begins to look wilted - a clear indication of a plant needing moisture. This is why it is so important that they receive the appropriate amount of moisture because they rely on water to live long and healthy lives. Plants are pretty cool beings, aren't they?
How to Water Your Plants
For the majority of houseplants, when it comes time to water a plant, it is important to water the plant fully, so that all of the soil is moist, not just the center, and not just the top. Now, the amount of water will of course depend on the size of the pot since a cup or two would be enough for a smaller pot but not for a larger pot, so it is important to ensure that all of the soil has been watered. Roots can exist anywhere in the soil, near the top, in the middle, but especially at the bottom, and they are the ones soaking up that delicious moisture to support the portion of the plant that exists above the dirt.
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When it comes to watering your Cacti, Succulents, Snake Plants, ZZ Plants, or any other variety of plant that prefers the soil to completely dry out between waterings, it is very important that you do so before watering again, which can take weeks or even months, depending on light levels, time of year, and size of pot. Then, water your plant fully.
The best thing to do is to think about each plant's natural habitat when considering how much water they need and how often they need it. Are they are Succulent or Cactus that are native to arid desserts? Is it a humidity-loving fern that whose soil should never go fully dry? Is it an aroid, such as a Hoya or Philodendron, that loves moisture in the air but not excessive moisture in the soil? There are plenty of resources online that can help us learn exactly what our plants prefer, we also have lots of plant-specific care guides in the Plant Care portion of our website!
Watering Tip: Water your plant in a sink, then you can water without making much mess and the plant can be left to drain completely before being put back in its place.
There is no perfect numerical amount of water to give your plants since there are many factors at play, but for larger plants, pour water all over the top of the soil and then allow it to seep in. Repeat this until the soil is fully saturated and there is water coming out of the drainage holes at the base of the pot. Then, any water that has drained out should be removed and dumped out, if the plant is still sitting in its decorative pot of drip tray, as excessive moisture can lead to root rot and a drowned plant. For smaller plants, you can follow the above steps but you will need much less water to achieve the same result, which would be evenly moist soil.
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In the case where the soil does not seem to be absorbing any water, water is draining out right away (and it is not porous soil), or it is pulling away from the sides of the pot, try bottom watering instead! Take your plant out of its decorative pot, leaving it in its nursery pot with drainage holes, and place it in a bowl filled with water for about 30-45 minutes. Once the top of the soil begins to darken, lift your plant out, let any excess water drain out, then place the plant back in its regular location.
A cup or two of water here or there may seem like you are watering your plants, but they would probably prefer a good soaking when it is time to water, and then nothing until the next time they need a drink. The root systems of plants can be quite different, some have thin roots, some have thick roots, some have shallow roots, and some have roots that stretch deep into the soil. Watering appropriately will ensure all foliage is staying nice and hydrated and the roots have access to a healthy amount of moisture, as well as allowing you to keep a better idea of when the last time you watered your plant sufficiently was.
Watering Tip: Take your large-leaf or densely vining plants to the shower when it is time to water them. The showerhead will wash any dust that has accumulated on the leaves as well as watering the soil! Hosing your plants off outdoors during the warmer months would achieve the same result.
When to Water Your Plants
Knowing when to water your plants is probably the most difficult aspect of watering to fully understand, especially if you are a newer plant parent. So many factors go into the speed at which moisture in the soil is used up by the plant, including how much light the plant is getting, the temperature and humidity of the room the plant is in, the time of year, the size of the pot the plant is in, as well as each specific plant's needs. One of the biggest mistakes is to stick to an exact watering schedule because watering every day, or on the same day every week, will often do more harm than good. It's all about the look and feel, of both the plant and the soil.
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Since the majority of plants will go through a dormancy period during the cooler, darker winter months, they will need less water than they do during the warmer, brighter days of the active growing season.
Again, for specific needs of plants, we refer you to our individual product pages, which have a general guideline for how each plant prefers to be watered, still considering the aforementioned factors, as well as our care guides, which are much more detailed. Generally, plants that are in larger pots will dry out slower than those in smaller pots, and plants that are in brighter light will dry out faster than those in lower light. Another detail to remember is that humid air will keep soil moist for longer, but on the flip side, in the winter months, surface soil can dry out more quickly due to the drier air indoors, but that's not necessarily a good indicator of the moisture levels of the soil below.
All-in-all, the best thing to do is to push your fingers into the soil to determine the moisture levels and water based on the plant's needs. You can also check by weight, picking up your plant when it is time to water it, feeling how light it is, and then picking up your plant after watering it, feeling how heavy it is. Going forward, if you are unsure by looking at the plant, try picking it up and identifying if it should be watered based on the information you have gathered previously.
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There is actually an ideal time of day to water our plants as well! It is best to water them in the morning, when they can properly absorb the water before the strongest light of the day is in full force and causing it to evaporate. This is also a good strategy for plants kept in lower light, the multiple hours of daylight ahead will help to use the water immediately, so they’re not sitting in waterlogged potting mix for too long.
Some plants prefer dry conditions, some plants prefer evenly moist soil, some plants prefer mostly dry soil but plenty of surrounding humidity, so try to be patient with yourself as you learn which plant prefers what! Our general guidelines, based on the moisture levels a plant prefers, are outlined below, but please bear in mind that they will all vary based on environmental conditions and watering frequency should generally be decreased for plants in lower light as well as during the darker, cooler months:
Plants that prefer fully dry soil
(e.g. Succulents, ZZ Plants, Snake Plants, etc.)
They like the soil to be completely dry before watering next. This can take up to 4 weeks in an average home environment. For them, it's always safer to underwater or water when you see signs of lack of water (i.e. wrinkly or soft leaves).
Plants that prefer mostly dry soil
(e.g. Pothos, Philodendron, Fiddle Leaf Figs, Hoya, Peperomia, etc.)
They like the soil to be relatively dry before the next watering. That usually takes about 2 weeks in an average home environment. For them, it's safer to underwater or water when you see signs of lack of water (i.e. droopy, floppy, or soft leaves).
Plants that prefer half-dry soil
(e.g. Alocasia, Anthurium, Calathea, etc.)
They need to be watered when the top half of the soil is dry to the touch. That usually takes about 1 week in an average home environment. It's always safer to underwater a little bit or give the soil a check before you water again.
Plants that prefer evenly moist soil
(e.g. Marsh Pennywort, some Palms, Nerve Plant, etc.)
Allow the top quarter of the soil to dry before watering again. This usually takes about 3 - 4 days in an average home environment.
Rather than watering on a schedule, the frequency of watering should be based entirely on what each plant needs, which you will certainly learn over time and with experience!
What to Water Your Plants With
If you thought a whole article on how to water your plants was already self-explanatory, you may be questioning this subheading. Yes, we still water our plants with water, but what kind of water is best for our plants? In their natural environments, plants are watered via rainwater as well as water from standing sources on or just below the surface of the forest floor, which is filled with beautiful nutrients to support thriving foliage. This water is most often warm (not hot), tepid, or lukewarm water as well, and warm water will absorb into the soil the best so avoid using cold water, which can shock the root systems.
If you can, try watering your plants with any of the following, in descending order from most favourable to least favourable:
Rainwater:
Rainwater doesn't have all the chemicals that tap water is treated with, such as salts, chlorine, and fluoride, which can burn the foliage of plants. The nitrate and ammonium forms of nitrogen also come down in the rain and are immediately taken in by plants through roots and leaves, while the water is also cleansing salts from the root systems. Finally, rainwater is highly oxygenated, which provides a margin of safety from excess water when soil is saturated.
Distilled water:
Distilled water is essentially dead water, as in everything has been removed from it by boiling it. So, yes, the bad chemicals have been removed, but the healthy minerals have also been removed. It is still a great option for watering our plants, just make sure you are fertilizing appropriately as well.
Filtered water:
Brita filtered water is good for plants because it contains activated carbon that can remove impurities like chlorine, lead, asbestos, and benzene from the water. It would filter out some minerals that would be good for your plants but, again, just make sure you are fertilizing appropriately.
Tap water that has sat out overnight:
You can let tap water sit overnight to help purify it through evaporation, but this will not fully cleanse it. Evaporation will occur, but that’s the water itself (and chlorine) evaporating, which can cause the rest of the chemicals, like chloramine, to become even more concentrated in the water. Check your local annual water quality report before giving it to your more sensitive plants.
Tap water:
Tap water is, of course, just fine to water your plants with, the problem is that it has been treated with salts, chlorine, and fluoride, which are great for us but can affect our plants negatively. Certain species will often show some sort of stress from poor water quality, which appears in the form of brown edges/tips, discolouration, or spotting. That being said, these are mild concerns and most plants should do just fine being watered with tap water!
The type of water you use to water your plants is especially important with plants that have sensitive foliage, or are known to be rather finicky, such as Calatheas, Fiddle Leaf Figs, Spider Plants, some Philodendrons, and some Monsteras. Regardless, all plants need moisture to survive, so if tap water is all that you have, we wouldn't worry too much about using it.
Overwatering vs. Underwatering
One of the most confusing words in houseplant care terminology is overwatering. This is because people usually take this word to mean that they are giving their plants too much water at any one time, but that couldn't be further from the truth! As we mentioned previously, it is much better to water your plants fully when they are thirsty, rather than a cup here and a cup there. That's because we want their entire root system to be completely nourished, as well as encouraging the roots to grow down and not build up at the soil surface.
Overwatering is when a plant is watered fully but too frequently, and the soil is kept constantly moist or not enough time between waterings takes place. This is something especially important to keep in mind when plants are kept in lower light, since they simply don't have the energy to use up all that excess moisture, as compared to plants in higher light. Now, this doesn't mean that all bright light-loving plants want to be watered all the time, think of Cacti and Succulents, it's just a general rule of thumb that plants in brighter light will need to be watered more frequently compared to those in lower light, and vice versa. For specific needs, please see our plant product pages. Learn more about overwatering in our blog: The Mystery of Overwatering.
On the other hand, we also don't want underwatering to take place, where plants are not watered frequently enough. It is vital that plants receive the appropriate moisture at certain times of the year to support healthy growth or lack of growth. In the dormant season of winter, when plants are not actively growing due to lower light levels and cooler temperatures, they generally won't need as much water as those in the growing season of spring and summer. This is why watering shouldn't be done on a schedule because the conditions of each home are different, as well as one specific home having different conditions at separate times of the year.
All-in-all, plants need water to survive and now you know why it is so essential. Knowing what you know now, consider your plants, the light levels that they are receiving (or should be receiving for optimal growth), and the moisture preferences each plant has before watering, every time you water it, your plants will thank you later!
