Watering your indoor plants with compost tea can help them stay vibrant and lively. What is compost tea, and how does it help your plants?
Here’s what you need to know, including how to make your own compost tea and how to use it for your indoor plants.
What Is Compost Tea?
Compost tea is a nutrient-rich liquid made from soaking compost in water with constant aeration. It’s a useful way to add nutrients to your indoor plants without overwhelming them or adding too much organic material to the soil. Compost tea also has a lot of microbial growth that can be beneficial to the soil in your indoor plant pots.
While compost and other fertilizers will pack a lot more of a punch, compost tea provides nutrients in a broken-down form that’s ready for immediate use by your plants. You can water your houseplants with compost tea daily if needed, as long as you make it correctly.
Compost Tea vs Compost Extract
Turns out, there are a few different things that are sometimes referred to as compost tea, one of the most common being compost extract. Although they’re made through a similar process, there’s a significant difference in how they’re made.
Compost extract is made by soaking mature compost in water until the nutrients leach out. The compost usually sits in water for a few days, getting stirred once or twice a day. There’s no aeration involved.
Compost tea is made in almost the same way but with constant aeration while the compost soaks.
The difference is in what the mixtures put into your soil. While compost extract adds mainly just the watered-down nutrients, compost tea also puts more beneficial microorganisms into the soil. Over time, these microorganisms make your plant pot soil a more hospitable environment for growing.
Making Compost Tea
Although it’s not made like traditional tea, people refer to the process of mixing up a batch of compost tea as “brewing”. Here’s how you can brew your own compost tea at home!
Brewing Time
Compost tea takes around 2-3 days to brew fully. Around 24 hours of this time is used to dechlorinate your tap water. You can brew it more quickly if you already have chlorine-free water.
Compost Tea Ingredients
- 5-gallon bucket
- Small aquarium pump or aerator
- Mature compost (1 cup per gallon)
- 3 gallons of dechlorinated water
- Molasses (optional)
- Mesh bag, cheesecloth, old pillowcase, grow bag, or similar (optional)
How to Brew Compost Tea
This is the basic process for brewing your own compost tea:
Step 1: Dechlorinate your water
If you have dechlorinated water already, you can skip this step.
Dechlorinating water is simple. All you need to do is fill your 5-gallon bucket with around 3 gallons of water. Let it sit outside in the open for at least 24 hours. Because chlorine is fairly unstable in water, it will evaporate on its own without you needing to do anything.
Step 2: Set up aerating pump
With your water ready for use, you need to start the brewing process by setting up your water aerator (or aquarium pump). It’s as simple as placing the pump heads into the bottom of the bucket and plugging in the pump.
Make sure the pump body stays away from the water. Only the pump heads should be submerged in the water. If they don’t stay in place, you can put a small rock on the hoses near the end of the pump heads or tape the pipes coming up the side of the bucket.
Step 3: Prepare & add compost
Get 3 cups of fresh, mature compost ready. Mature compost should have a sweet, earthy smell. Don’t use compost that includes animal manure.
You want 1 cup of compost per gallon of water in your compost tea.
Either add the compost directly to the water or put it into a container first, such as a mesh sack or old pillowcase.
The advantage of using a cover is that you won’t have to filter your compost tea later when you’re pouring it out. You’ll reduce the mess and make it easy to get the compost back out.
Step 4: Mix in supplemental ingredients (optional)
If you’re going to add any supplemental ingredients to encourage beneficial microbial growth, add them now. Common supplemental nutrients include:
- Unsulphured molasses
- Natural sugarcane juice
- Kelp meal
- Fish meal
These supplements help to stimulate microbial growth in your compost tea. You’re likely to get higher concentrations of beneficial bacteria when you use supplements, but it’s not a necessity.
Step 5: Brew for 24-36+ hours
Place your bucket out of direct sunlight before starting the brew.
Once all your ingredients are mixed in, turn the pump on and leave the compost tea to brew for at least 24 hours straight. During this time, stir it occasionally. Leave the pump on for the entire brewing time.
You’ll know the compost is finished brewing when it has an earthy smell and bubbles covering the surface.
Step 6: Strain to remove compost – then water your plants!
Turn off, unplug, and remove the air pump.
If you put loose compost into the brew, place a cloth, grow bag, or strainer over the top of another bucket and pour the compost tea through it to remove compost bits.
Pour the strained liquid into a watering can, and voila! You’re ready to water your houseplants as usual!
Note: Use compost tea within 4-8 hours of turning off the pump, or the microbial growth will die from lack of oxygen.
Cleaning Up
Any equipment you use to brew your compost tea should be cleaned well after each brew. Clean the pump and bucket, as well as the sack you used to hold or strain the compost. Sanitize them in hot water or leave them sitting out in the sun for a while to kill any excess bacteria.
Empty the strained compost bits back into your garden.
Do You Need to Aerate Compost Tea?
Yes. Compost tea needs to be aerated while it’s brewing because the microorganisms you’re trying to breed need oxygen to survive. If you don’t aerate the compost tea while it’s brewing, you’ll end up with compost extract that doesn’t include beneficial microbial growth.
This isn’t the end of the world, but if it’s beneficial microorganisms you’re looking for, you need aeration.
Applying Compost Tea to Your Potted Plants
Although some sources talk about applying compost tea to leaves, there’s no evidence that this helps your plants at all. Plants don’t absorb nutrients well through their leaves.
Instead, apply compost tea in place of water. Don’t worry, it’s highly diluted, so it won’t harm your plants! You can dilute it further if you want to apply it every day. Simply mix your compost tea with water before applying it.
If you’re watering every day or every few days, make sure you’ve set up your plant pots well to handle the water you’ve giving them.
Affordable Air Pumps for Compost Tea
Don’t let the air pump scare you away from making your own compost tea! They’re super cheap and will last a long time since you’re only using them once in a while.
The only thing you really need to look for is a pump with dual outlets.
Here are a few simple air pumps for compost tea that are all under $25:
| Capacity | Number of Outlets | Standout Features | |
| HITOP Aquarium Air Pump | 20-100 gallons | Dual outlet | Quiet |
| Rifny Aquarium Air Pump | 80-250 gallons | Dual outlet | High-quality silicone |
| Uniclife 64 GPH Pump | 60 gallons | Dual outlet | Adjustable flow rate Quiet |
| AQQA Aquarium Air Pump | Up to 160 gallons | Dual outlet | Reliable Adjustable flow rate |
| NICREW UX5 Ultra Silent Air Pump | Up to 40 gallons | Single or dual outlet | Positive reviews from users making compost tea |
Compost Tea FAQ
How Often Can You Apply Compost Tea?
You can apply compost tea to your indoor plants every day if you want to. It’s a diluted mix of nutrients and microbes, so it’s unlikely to have a negative impact on your plants. Stronger fertilizers and composts should not be applied to plant pots, grow bags, or hanging baskets daily, but compost tea has a much subtler impact.
What Can You Use to Make Compost Tea?
All you need is water, mature compost, and a source of air bubbles. Make sure you’re using mature compost that’s fully decomposed. Avoid compost that’s got a lot of animal manure in it since this can introduce harmful bacteria to the mix.
Does Compost Tea Really Work?
That’s debatable. When it’s brewed correctly, it can have a small positive impact on your plants over time. However, since it’s a highly diluted source of nutrients, compost tea won’t have an extreme impact.
It’s a good source of regular nutrients for indoor plants since these don’t have the same exposure to organic materials and rainwater as outdoor plants, including office plants that stay indoors all the time.
Think of compost tea the same as you would an herbal tea brew for yourself. It may not be enough to keep you healthy on its own, but it’s definitely beneficial, and it certainly doesn’t hurt!
Can You Use Compost Tea on All Plants?
Yes, you can use compost tea on all indoor plants and planters. Unless a plant has very specific watering or nutrient requirements, you can use compost tea on any indoor and outdoor plants.
How Long Does Compost Tea Last?
Compost tea only lasts for around 4-8 hours after it finishes brewing. Once you cut off the oxygen source, microbes can begin dying off within 4 hours, with their level going down significantly within 8 hours. Make sure you only brew compost tea when you’re going to be using it.
Can You Apply Compost Tea to Plant Leaves?
You can do foliar application of compost tea, but I wouldn’t bother. Most plants absorb nutrients through the soil rather than their leaves, so it’s likely to be a big waste of time to apply your compost tea to the leaves instead of just watering the soil with it.
