Do You Need A Humidity Tray For Your Bonsai?

I am often asked if humidity trays are important and if they are needed; the reality is that they are not really.

Most bonsai will be fine without them, but there can be a few tropical trees, or very small mame trees that can benefit from a humidity tray.

What Is A Humidity Tray

A humidity tray is just a tray that you sit your bonsai pot on. The tray contains water and as this evaporates away it causes the area around the tree to be more humid.

Are Drip Trays And Humidity Trays The Same Thing?

A humidity tray and drip tray are often seen as the same thing and you will find the name is interchangeable, but there are some subtle differences. 

A humidity tray is deeper than a drip tray and this is because it is filled with water. Usually the tray is lined with small stones or gravel, which the bonsai pot sits on. This will keep the pot from sitting directly in the water.

Of course a humidity tray will also catch anything that drips out of the pot, so it is also technically a drip tray too.

Do You Need A Humidity Tray For Your Bonsai?

As with most things in bonsai, it depends. You might need one, but honestly the majority of trees do not need one.

Outdoors

Outdoors trees will not usually need a humidity tray, you can just leave the pot sat on a bench and it will be fine. They don’t need extra humidity and they don’t need any sort of drip tray as excess water can just fall to the ground.

However, the exception would be very small mame trays. I have seen these being placed in humidity trays during the summer.

These small trees dry out very quickly, so having that extra water evaporating around them actually slows down the rate at which they dry out. This can literally save their life as they can completely dry out in a few hours and die without this.

Indoor

I would say a drip tray is needed more than a humidity tray indoors. A drip tray is going to catch anything coming out of the pot, which is going to protect your house.

When it comes to humidity, this will depend on what species you have and also how dry the air in your house is. I would say that most people’s houses are humid enough and a tray isn’t really needed. Although you will need to measure what your humidity is and also see how your tree are growing.  You may find that some extra humidity helps, although you would get better results using a humidifier.

If you are growing mame inside, then these could again benefit from the extra water from a humidity tray, as I discussed above.      

How Do You Use A Humidity Tray?

Using a humidity tray is pretty easy. You just need to line the bottom with stones. You can fill the tray up to about the lip, that is usually going to be more than enough.

The stones look decorative, but also allow the pot to sit up a little bit from the bottom of the tray.

You can then fill the tray with water, up to the level of the stones. Now your tree is sat in water… but is not directly touching it due to the stones.

The water will evaporate away and will need refilled every so often.

Do You Need To Fill Humidity Trays With Stones?

If you are trying to use your tray as an actual humidity tray then stones are probably a good idea.

You could just fill it water and place the tree in, but then the base of your pot will then be sat in water. Usually we want to avoid this, as we don’t want the roots being constantly sat in water. The stones raise the tree up ever so slightly, so it stops it coming into direct contact with the pot.

However, sometimes it can be okay for the bottom of the pot to be touching the water. This would be when you are growing mame trees and you want the tiny pots to able to pull some water from the humidity tray, as the pot is not big enough.

Although even in this instance I would still use some stones, maybe just a thinner layer so that it is just ever so slightly touching the water, rather than actually submerged.

I also think it is important to note that most bonsai pots have legs, so even did you didn’t use stones, most pots could still be stood above the water by themselves. If your tree is in a pot with a flat bottom, such as a flower pot, then I think stones would be necessary as the stones are going to raise the pot up and away from the water.

Using Stones For Aesthetics 

Even if you do not really want to use the humidity tray for its main purpose and you just want to use it as a drip tray, you can still add stones.

If you are just using a plastic tray, some stones can make it look nicer, although that plastic is always going to be visible, so it’s not the perfect cure but I do feel it can make the situation look better in general.  

(You can read more about – Why Do People Put Stones Around Bonsai Trees?)

What Type Of Stones Should You Use?

When it comes to stones, any sort of grit of gravel is going to work. I have always used a natural coloured aquarium gravel and it was perfect. They look good and are a nice size. Your pot can sit on this style of gravel quite nicely. I think if you used a larger stone it might look weird, but really it’s down to you, so long as it’s a stone that isn’t going to dissolve it will be fine.

I have seen people suggest using bonsai soil, or even pure akamada. I wouldn’t do this. Grit and gravel is going to be perfect as would lava rock, these are all going to have plenty of air gaps to allow the water to filter through, where as soil can hold the moisture, even if it is still full of gaps. Using soil is also going to encourage the roots to work their way into it, which isn’t really want you want.    

You will also see people using pebbles, especially slightly larger and smoother ones, which can give the feeling that they are river pebbles, especially with the water, so they can look cool.

Humidity Trays Can Help When You Go On Holiday

I have actually found the deep trays very helpful for when I want to go away for a few days. I simply just water my tree and fill up the trays with water.

This does mean the water is up to the level of the pot, which is normally not ideal, but for a few days it will be fine. This extra water means the tree they are a bit wet for a few days, which is perfect, since I’m not around to actually water the trees. 

(You can read more about – Looking After Bonsai Tress While On Holiday)

Do You Still Need To Water Your Bonsai If You Use A Humidity Tray?

I would also suggest that you water your tree before you add any additional water to the tray. When you water a lot of it will pass straight though, so obviously if the tray is already full then you run the risk of it over flowing and causing a mess.

I liked having the stones in the tray, even though I wasn’t using it as humidity tray and adding water, it allowed me to water the tree while it was in position and any excess water would easily flow out. I like that the stones raised my pots up and kept it away from this excess water. I then just let nature do its thing and let the water evaporate.      

(You can read more about – How To Water A Bonsai)

Conclusion

Hopefully now you can understand if you need a humidity tray or not, which for most of us, we don’t need one. Really you only need one if you are growing mame trees or your house has extremely dry air.    

You can play around with using one and see if you notice any significant difference, I don’t think you will apart from in a few rare instances.