Complete guide to bottom-up watering plant container gardens
Updated: Apr 11, 2022
How many of us have killed a plant with water? I'm sure most of us have, at least once!
It's impossible to tell whether you've watered too much or too little. That's why watering is the number one killer for house plants.
Watering plants is not as easy as it seems. I actually switched to bottom-up watering because I had more success that way.
Thu plants are getting the water at the roots which are where they need it most. In fact, there are some plants like the African Violet that should not be watered from the top-down as the leaves will turn yellow if they stay wet for too long!
What is bottom-up watering?
Bottom-up watering is when you place a container underneath your plant pot and water the container instead of the plant pot.
This way the plant will essentially water itself by sucking up the water from the container.
Bottom-up watering is an advantage because the plant will take all the water it needs and you don't have to worry about whether it's been watered properly or not.
I also find that the plant container will stay moist for longer when it has been watered from the bottom up because the whole container gets moisture rather than the water potentially falling down the sides.
Also, if you have new seedlings or microgreens then you need bottom-up watering. I once destroyed many seedlings by watering them and crushing their dainty stems by accident. Oops!
See below for some commonly asked questions about bottom up watering
What do I need for bottom-up watering?
You'll need a plant pot with drainage holes and a container to hold water. The container can be any solid container to hold water, anything from a bathtub to a baking tray will do fine.
I prefer to use:
or even ordinary dinner trays.
I keep the containers permanently under the plant pots so that I don't have to move them around when I water.
Can you overdo bottom-up watering?
Yes because you could add way too much water to your reservoir and it could sit there for longer than intended.
Let's say you check back the next day after watering them the previous afternoon, and the water is still there, that's a bit much water and you'll need to chuck the remaining away.
All the water should be gone in a few hours.
If you accidentally do this then your plants might suffocate as they need air in the soil to breathe.
Or you could turn your soil anaerobic which means the bacteria are no longer the oxygen-loving bacteria that are great for plants, but instead they are de-oxygenated bacteria that are harmful to your plants.
Why is bottom-up watering not working?
If bottom-up watering is not working then the problem is likely to be with the drainage check the following:
Check that the holes in the bottom of your plant pot aren't too small. If so, you could try and make them wider or use another pot.
Check that the drainage holes are not blocked. Sometimes soil can get compacted at the bottom of your pot. Try sticking a sharp object through the drainage hole to loosen it up a bit.
Your plant pot may not have enough air pockets in it allowing water to travel through. If this is the case you could try using vermiculite or perlite in your soil mix to make some air pockets.
Your plant pot might be root bound. This is when the roots have overgrown in your pot and just keep going round and round taking up all the space. You can replant it into a bigger pot to resolve this.
Can I water plants in a bathtub?
Yes! you can certainly water your plants in the bathtub.
First of all, make sure you clean your tub and remove shower gels or soaps. You don't want soapy water as the chemicals are harmful to plants.
Once that is done, fill the tub with shallow water. Make sure that there isn't enough water to submerge your plants or go over the top of the plant pot.
You can leave your plants in there for a couple of hours and then place them back in their home.
This method is perfect if you have a lot of plants and want to get them all done at once.
How long should I leave plants in water during bottom-up watering?
This depends on the size of your pot, how thirsty they are, and how aerated your pot is.
Let me explain.
The bigger the size of your pot, the longer it will take to suck up the water.
If you haven't watered in a long time, the plants will suck up the moisture quicker than if you just watered yesterday and there's still moisture in your plant pot.
If your plant pot is tightly compacted - meaning there aren't many air holes in your soil, then there isn't going to be much leeway for water to travel up your plant pot and it will take a long time for water to spread around your pot.
Generally, plants should take up all the water slowly within an afternoon I'd say about 30 mins to an hour for a small pot, and 2-4 hours for large pots.
How can I tell when bottom-up watering is complete?
It can be quite daunting at first to know when it's done but the answer might be easier than you think, you can just dig your finger in the top of the pot and if it is moist then you can be sure the whole pot has been watered.
Sometimes you don't have to touch but just look. When moisture reaches the top, the soil that is watered will turn a darker brown (I notice this with my coconut coir soil mix).
Can you do bottom-up watering overnight?
Bottom-up watering overnight is fine. It is the same as during the day actually. Just fill your reservoir with water before you go to bed and then check on it in the morning.
Dip your finger into the top of the pot to see that it is moist and check that the water is all gone from the reservoir in the morning.
If there is some water left, chuck this out to prevent the soil from going anaerobic or suffocating your plant from oxygen.
Can I bottom-up water more than one plant at a time?
You can water more than one plant pot in the same tray at the same time, just watch to make sure one pot isn't sucking up all the water.
Be careful if your tray is on the slanted ground as the water will pool on one side not providing enough water for the other plants.
I hope you found this useful, happy watering!