I know that the correct way to water houseplants is to water whenever it is dry. First, stick a finger in to feel its dryness, and then water until it drips through the drainage holes.

However, I have three large houseplants (ficus elastica, BOP, and philodendron rojo congo) that I honestly have no idea how to gauge when to water. Yes, the soil is dry when I stick my finger in -- but how can I tell if it's also dry throughout the entire ~50cm tall planter? And since they are older houseplants, the soil is more compact. Is this why I never see water drain through the bottom when I water them? Or am I just simply not watering enough? But I am also too scared to water more and cause root rot.

Any advice on how to know when and how much to water larger houseplants is appreciated! Thank you for taking the time to read this!

I use a chop stick to check the soil for moisture in my large plants, if the water is not draining you aren't watering thoroughly, pictures of the plants and their containers would help a lot.

Yes, what Christine said. You water thoroughly when the top half inch or so is dry. You would have overly moist soil in 90% of the pot with a dry top inch. Doesn't happen that way. Water is wicked upwards and if it is too moist below, the top is never going to dry.
When you water have the water drain through the bottom drainage holes. Use plastic saucers to catch the water if need be.
So much of house plant care becomes common sense. Don't over think it.

@BigBill I'm confused by your advice. Water when the top 1/2" is dry but the plant will be overly moist with a dry top inch? Can you clarify?

The soil in potted plants dries from the top down. The plants that you referenced never want to get dry deep in the root zone. If your plants are properly potted (not over potted) and there is no layer of loose soil on top of the original rootball, then your plants can be watered when the top inch of soil is dry. That is about as far as you can insert your finger. The soil below that level will remain damp, as it should.

When you water, always add enough so that some runs through the drain holes. If no water runs through, it may be because you did not add enough. But make sure the drain hole is not clogged by sticking a pencil or stick up into the drain hole. As long as excess water can drain out and you allow the top inch of soil to dry, you don't need to worry about root rot.

No you misunderstood me. I was responding to something you had said. Just stick to watering when the top half inch gets dry. You won't have a half inch of dry soil sitting on top of 10" of mud! When the top dries, that's when you know to water.

In that size pot (just under 20" deep) I'd go with the top inch being dry, but having said that I more often go by weight. You don't need to lift up a big pot but carefully tipping it to one side a little can give you an idea of the weight. If it feels heavy for its size don't water, if it feels very light it is too dry, you want to aim somewhere in between.

Great point sooby, great point!
Mind if I use that?

Hi everyone,

Thank you so much for all the tips -- I really appreciate it! I feel much more confident about my watering. I will definitely try out the chopstick idea, both to check moisture deep inside, and to insert into the drainage holes to make sure they aren't clogged.

These are the plants in question. The BOP was a rescue so its leaves are a bit tattered, but it's putting out new growth! And my cat for scale! I also had a concern about my philodendron rojo congo, which I will be making another post on the forum. But they all appreciate your help!

mogumei said: And my cat for scale!

Please post a photo of the cat next to an extended measuring tape. We need to know how big the cat is.

Everything in your photos looks very healthy so I'd just keep doing what you're doing!

Your plants look beautiful (kitty too!) so I say keep doing what you've been doing!

I agree,your plants look really good, love your cat, I have a black cat too.

Sue, I check some of my smaller pots by lifting, after having some of them for years you just know each plant 💚