How frequently a houseplant needs to be watered is determined by several factors that all affect how quickly a plant dries out.
We are going to cover what those factors are and why they matter so that you can begin to observe your houseplant and its environment to gain a deeper understanding of what it needs from you to survive and thrive.
Table of Contents
- #1 How succulent is your plant?
- #2 How much light is your plant receiving?
- #3 How well-draining is your plant’s potting mix?
- #4 What material is the plant’s pot made out of?
- #5 How large is the root ball of the plant is in relation to the size of its pot?
- #6 What is the temperature of the space around the plant?
- #7 How humid is the area that the plant lives in?
- #8 Is your plant is dormant?
- #9 How do you water your plant?
- Big Takeaways
- Related Posts
#1 How succulent is your plant?
All plants have adapted to the environment they grow naturally.
Some environments, like the desert, rarely receive rainfall throughout the year. Other environments, like the rainforest, are almost always receiving some level of moisture/rainfall.
Plants have adapted to thrive in these extreme examples and everywhere in between by developing physical attributes that match the water availability.
Plants in the desert often develop very succulent, fleshy bodies that have spaces built in to store extra water to help them through times of drought. They are built to receive infrequent watering.
Plants on the forest floor of a rainforest (which receives lots of rain) may develop very thin, delicate leaves and stems that do not have extra space for water storage because they have no need to store water. They are built for receiving frequent watering.
Our watering practices should mirror what the plant is used to in the wild.
In other words, the more succulent your plant is, the less it will need to be watered. We want to allow succulent plants to dry out completely.
The more delicate and thin your plant is, the more frequently it will need to be watered. More delicate plants aren’t built to withstand periods of drought. We want to ensure we water these plants either right when they are dry or right before they dry out.
#2 How much light is your plant receiving?
The amount of light a plant receives changes how much a plant grows, how healthy the plant is, and how frequently a plant will need to be watered. Here’s why:
Plants receiving more light will be able to perform photosynthesis more frequently and regularly.
Photosynthesis is the process a plant uses to create food/glucose/energy for itself to continue to live and grow.
A critical component of photosynthesis is water. In other words, the plant must have access to water to photosynthesize.
So…. if the plant is receiving more light, it will be able to photosynthesize more frequently. If it is photosynthesizing more frequently, it will be using up the water it has access to more quickly as well.
Therefore, higher light levels support lots of photosynthesis which generally means more frequent watering.
#3 How well-draining is your plant’s potting mix?
The amount of drainage in a potting mix changes how quickly and easily water passes through the mix and how much moisture is retained in the pot.
Most commercially available potting mixes contain peat moss as their base ingredient. Peat moss is really good at retaining water, which makes it well suited to potted plants.
“Over thousands of years, plant materials submerged under water in bogs have broken down to form a type of soil called “peat”.Dr. Leonard Perry, University of Vermont, “What is Peat Moss?” Source
Most common is peat from the sphagnum moss plant.
Don’t confuse the peat from dead plants with the actual sphagnum moss from living plants. Sphagnum moss often is seen as a liner for hanging baskets. This moss grows on tops of such wetlands, and is harvested first, then the peat below.
[…] Peat is what firms harvest, often drying out the bog temporarily so they can suck up the peat with vacuums. The peat is then dried further, screened, and compressed into the bales of peat moss–this final product– that we buy in stores.”
Often, peat moss (as the sole ingredient in a potting mix) is too good at retaining water when growing plants indoors because the plant isn’t receiving enough light and heat to use up the water quickly.
Why is this bad for the plants?
Most plants’ roots are not equipped to sit in wet conditions for extended periods of time (because that isn’t what their natural environment offers them). So roots that are in wet conditions for too long literally drown and eventually die and rot away, causing the plant to decline and die as well.
What kinds of things are added to increase drainage and decrease prolonged wet conditions? Perlite, Pumice, Orchid bark, Horticultural Charcoal, and more.
The more chunky, airy substrates we add to our peat moss, the more quickly water passes through.
A more well-draining potting mix has less moisture retention, which means that the plant dries out more quickly and will be ready for a thorough watering more quickly.
#4 What material is the plant’s pot made out of?
Some materials used to create a planter or pot can help to reduce excess water around the plant’s roots. Other planter materials will help to keep in the moisture for longer periods of time.
Unglazed clay pots, like terracotta, are porous, which allows water to pass through the clay. This creates a wicking action that pulls some of the moisture out of the potting mix of a plant, helping to prevent wet conditions for long periods of time.
Glazed pots and plastic pots do not have these pores and, as a result, hang onto a lot more moisture for a longer period of time. This can be very advantageous if you want to water less often or you have a plant that absolutely hates to dry out (like most ferns).
It can also be a big drawback if you have a plant that doesn’t want a lot of moisture around its roots all the time.
#5 How large is the root ball of the plant is in relation to the size of its pot?
The amount of space between the sides of the pot and the sides of the root ball changes how much extra space there is for moisture to linger around the roots.
Most houseplants do not want to stay in wet conditions for a long period of time AND their roots can only suck up so much water in a healthy amount of time.
If the root ball is tiny compared to the size of the pot, the plant won’t be able to use all of the moisture surrounding its roots and the plant will develop root rot.
If the roots have consumed nearly the entirety of the pot, there will be so little space for moisture around the roots that the plant may dry out super quickly or possibly never feel fully hydrated.
The optimal setup for your plant is to have its root ball consume about 2 thirds of the pot with the remaining one-third filled with potting mix that provides both moisture and room to grow. (like the plant in the middle of the diagram below)
If that isn’t the case, then we need to adjust our watering based on our understanding of the size of the root ball: a small root ball in a big pot means less frequent watering; a large root ball in a small pot means more frequent watering.
#6 What is the temperature of the space around the plant?
Just like we dehydrate faster on hotter days and need to drink more to stay hydrated, so do our plants.
For example, if the room where a houseplant is located is super hot in the summer, it’s likely that your plant will be consuming a lot more water than if it were to be in a cooler setting.
#7 How humid is the area that the plant lives in?
The humidity level of the area a plant is located in also affects how quickly a plant dries out.
Humidity is literally the amount of water vapor in the air. If the air is already quite humid and saturated, the water in your plant’s potting mix isn’t going to evaporate super quickly.
If the air is very dry (like in winter for many of us), the water in a plant’s potting mix will evaporate much more quickly.
Plants also lose a little bit of water each time their stomata (pores on the plant that open to absorb carbon dioxide) are open. The amount of water they lose changes based on the humidity and temperature in a space.
Some plants have adapted to only open their stomata at night when the temperature is cooler and the air is a little less dry. These are typically plants adapted to extreme environments, like the desert, where water conservation is super important.
In conclusion, the more humid the room is where your plant lives, the longer the plant will take to dry out. The drier the air is around the plant, the faster it will dry out.
#8 Is your plant is dormant?
Plants often use dormancy as a way to survive periods where the environment doesn’t offer favorable conditions.
For example, a lot of the trees that grow in my home state of Michigan go dormant in winter to survive the cold, freezing temperatures.
Some plants need this period of dormancy to survive and thrive at their best; it is built into their DNA to expect a period of dormancy. Some plants do not require dormancy but have it as a tool when needed (like when light levels are too low, conditions are too dry, or the environment is too hot or cold).
Since dormancy is a period of rest, not so dissimilar to us sleeping at night, plants require a lot less water.
How do you know if your plant is dormant? Unfortunately, this one doesn’t necessarily have an easy answer.
Some clues that your plant might be dormant: it has stopped growing; it is taking much longer to dry out; it is dropping its leaves
It typically requires looking into that specific plant and determining what dormancy looks like for that plant and when dormancy typically happens.
Why? There are plants that grow in winter and go dormant in summer. There are other plants that go dormant in winter and grow in summer. There are also plants that never go dormant. It truly depends on the particular plant.
Even then, plants that may typically go dormant during a specific season may never go dormant in our homes because the conditions aren’t changing enough for the plant to know its time to go dormant.
Sometimes dormancy is super apparent, like when an Alocasia loses all its leaves, but plenty of time the plant isn’t so obvious. And even if you know a plant likes a period of dormancy, it can still be difficult at times to decide whether the plant is dormant or dying.
So research is the best way to find out whether your particular plant might be dormant.
#9 How do you water your plant?
The last factor that dramatically changes how often a plant needs to be watered is how you provide your plant with water.
The correct way to water a plant is to thoroughly saturate its entire pot until water runs out of the drainage holes.
This will help to ensure that the entire root ball receives water evenly.
However, many of us (including me) may sometimes quickly water a plant as we walk by and not ensure that the entire pot is saturated.
This can create uneven watering conditions where only part of the root ball is getting the hydration it needs and the plant will be thirsty more quickly because it was never fully saturated.
To give your plant the best conditions, ensure it is thoroughly watered from top to bottom but not left sitting in a water puddle. Dump any excess water out of a plant’s saucer!
In summary, lots of factors, individually and together, affect how quickly a plant uses the water we provide. Knowing what these factors are and how they affect our plant’s thirst can provide us with fantastic clues about how to correctly water the plant.
For example, if we are noticing that the sun is coming out more often and the temperatures are rising after a cold winter, we can use that as a clue that our plants are probably receiving more light and using water a little more quickly.
To help you determine what these clues might mean, I’ve created a chart below to summarize them. I hope this helps all of you develop a deeper understanding of your plants and how to water them.
Needs to be watered more frequently
Soil with lots of perlite, pumice, bark, and other chunky stuff
Clay pots that are porous and unglazed
Plants in high light
Plants in higher heat
Plants in lower humidity
Plants with root balls that take up most or all of the pot (especially rootbound plants)
Plants that are actively growing and thriving
Needs to be watered less frequently
Thick, succulent leaves
Soil without chunky additives for drainage
Plastic and glazed pots
Thick, succulent stems
Plants in low light
Plants in cooler temperatures
Plants in high humidity
Plants with smaller root balls that leave a lot of space for potting mix and moisture
Plants that are dormant and resting