Watering indoor plants seems to be one of the most complicated things for new gardeners to learn, which is surprising since it’s really simple. The problem is that a lot of the information out there makes the subject complicated and it gives new gardeners bad advice.
In this post I am going to give you some simple rules that work for any houseplant and makes watering easy. I’ll help you decide when to water and show you the best way to do it.
How Often Should You Water Indoor Plants?
New gardeners always ask, “how often should I water my plant”, and lots of people on social media, and online, will give you an answer. They are all wrong! If you learn only one thing from this post, please learn this.
You can’t water plants on a regular schedule.
If you try to do that you will always have trouble.
The frequency of watering depends on too many variables, including type of media, type of pot, size of pot, amount of light, room temperature and humidity, and both the size and type of plant. All of these things change throughout the year which means that the watering frequency also changes.
Don’t get discouraged – there is an easy solution.
Not All Plants Need the Same Watering
Indoor plants can be grouped into three categories, according to water needs.
Some plants like to stay wet all of the time. This includes things like pitcher plants, sundews, baby’s tears, spikemoss, caladiums, and umbrella palms. This is a specialized group and includes very few of the common indoor plants.
The second group are plants that like regular moisture, but they also like the soil to dry out a bit. I’ll call these semi-dry. This group includes the vast majority of indoor plants and it includes most tropical houseplants.
The third group of plants like to dry out between watering. This includes orchids, cactus and almost all succulents.
Do a little online research and figure out which category of plant you have. If you are unsure, treat it like a semi-dry plant.
I’ve made a separate video on watering orchids.
Myth: Too Much Water Will Kill Your Houseplant
There is a common saying, “most houseplants are killed with too much water”, but it is a myth. Using too much water, when you water, will not kill any plant. What kills plants is watering too often. It is the frequency of watering that kills plants.
If I add a cup of water to a plant every day, it may be dead in a week. But if I add seven cups of water on day one, and let it sit for a week to dry out, it will thrive.
Put another way; soil that stays wet all the time kills plants. Wet soil that dries out does not.
How Do You Know When to Water?
Group 1, the wet plants, should be watered once the very top to the soil starts getting dry, or even the day before. Some of these plants are happiest sitting right in water, but not all of them.
Group 2, the semi-dry plants should be watered well and then left alone until the top one inch of soil is dry. Don’t water sooner, and waiting an extra day or two won’t hurt. The soil in the center of the pot should never be completely dry.
Group 3, the dry plants, should be left alone until the soil is dry down to the middle of the pot. In most cases, letting the pot completely dry out will not harm the plant, especially in cooler or low light conditions.
These are simple rules that tell you when to water, but how do you know how dry your soil is?
The Worlds Best Moisture Meter
You might be inclined to use a moisture meter, but they are completely unnecessary. The best moisture meter you can use is your finger. It never stops working and you never have to replace the batteries.
Stick it in the soil and you can easily feel the moisture. If the very top is dry, it is time to water the group 1 wet plants. Once the top inch (2.5 cm) is dry , water group 2, the semi-dry plants. If you feel any moisture when you stick the finger in deeper, don’t water the dry plants yet.
If you are unsure about watering, wait a day or two; it won’t harm most plants.
As you stick your finger in the pot, lift the pot and gauge how heavy it is. At first this won’t mean too much to you, but as you practice it over the next couple of months you will be able to tell how dry a pot is just by its weight. After that you no longer need to use your finger.
You now know the perfect time for watering, but how should you water?
Critical Rule About Watering Indoor Plants
The basic rule is simple. When you water, water a lot.
Don’t give your plants itty bitty sips every day and don’t use ice cubes. You want to thoroughly soak the soil and then wait until it’s time to water again.
Most potting soil is not really soil and is more properly called potting media. It usually consists of a lot of peat moss or coconut coir. Both of these hold a lot of water and air, making them ideal for potted plants. Unfortunately, they are hard to wet once they are totally dry.
Once dry, the media shrinks away from the sides of the pot and water just runs through this crack. Neither the media, nor the plant roots absorb any water and your plant will dry out and die. This is one reason why overhead watering is not a good option, especially for beginners.
A much better way to water your plants is to sit the pot in a larger outer pot that does not have drainage holes. Fill it mostly with water, and let the plant sit for 20 minutes. Even up to an hour is OK. This ensures the media is properly soaked. Now take out the potted plant, and run more water through it. This will wash out any excess salts.
You are done. Let it sit until it is time to water again.
If it is time to fertilize, add the fertilizer after watering the houseplant.
Some people like to sit the pot in a saucer and let it soak up the water. This can also work, but make sure the media is fully wet. This probably requires you to fill the saucer several times. I find it easier to use the large outer pot as described above.
Try not to get the leaves wet. Hard water can leave unsightly stains just like the inside of your kettle, and that is not good for plants. Some plants, like orchids, have leaves that join the stem making pockets which hold water and in some cases this can cause bacterial rot. African violets are particularly sensitive to this.
Leaves don’t really benefit from having water on them although the occasional wash to get rid of dust can be beneficial.
You might have noticed that the above only works for pots that have drainage holes. If you have a plant in a pot without holes, repot it into one that does. Pots without drainage holes can work, but they make watering much trickier.
If you follow the above rules you will always have healthy plants.
Should You Water from Top or Bottom
This is discussed fully in Watering Houseplants – Top or Bottom? Which is Best?
Tips and Tricks for Watering Plants
Here are some more posts about watering plants.