Compost tea is a liquid solution or suspension made by steeping compost in water. It is used as both a fertilizer and in attempts to prevent plant diseases. Compost tea is made by steeping compost in water for a variable period (24-48 hours), then applying the liquid undiluted as a spray to plant parts, or as a soil-drench , such as to seedlings, or as a surface spray to reduce the amount of harmful bacteria and fungi on plants.
Step 1: Materials
There are two parts to the materials. The first group is to brew the tea, and the second set is to filter he tea for actual use.
1. Compost (I prefer to use organic manure compost, but any kind of compost will do)
2. Five gallon bucket, or any water-tight container
3. Unsulfered Molasses (This acts as food for the bacteria)
4. Air Pump
5. Hose for the air pump
For Filtering and use:
1. Another bucket
2. Wire mesh strainer
3. Cloth for filtering
Step 2: Mixing the Tea
Fill the bucket about a third of the way with the compost. After you have done this, pour in some molasses, I just eyeballed the amount, but it was roughly 1/4 of a cup. Then simply add the water, you want to fill up the bucket nearly to the top. You can see the ring in the bucket from where I've used it before. The reason for this is because this is a fermentation process, there will be gas bubbles that will form on top of the water, and you don't want this to over flow. I would recommend that if you are on a city water system, that you get bottled water or at least filter the water somehow, because city water will have small amounts of chlorine and fluoride which at least make the process take longer and at worst kill the bacteria that you are trying to grow. Once you have everything in the bucket, give it a stir.
Step 3: Set Up Air Pump
This step is very important because we are going to be making an aerobic tea. Take whatever kind of pump you have and set it up with the tubing. You will need enough of the tubing to ensure that it can reach the bottom of the bucket. You will also need to have some kind of weight on the end of the tube to make sure that it stays on the bottom of the bucket. I wouldn't recommend you use an "air stone" like you would in a fish tank, because they will get clogged very quickly and make very small bubbles. With this process you will want to have large bubbles of air. I just used an old socket for the weight, you can use anything at all for this. In the photo below, you can already see bubbles starting to form from the mixing process, these are very good.
Step 4: Brewing
Now that everything is set up, you need to allow the mixture to brew for 24-48 hours. I would recommend for this step that you do this outside and make sure that there is some type of cover on the container. The reason for this is because this will produce odors, just like regular compost this is waste material that is being allowed to rot. The cover is just to make sure that no other water will get into the container. It's not the end of the world if this happens, it just means that you would have to brew for a longer time. I simply used one of my trash can lids. If you are making this on a covered area, you don't need to worry about this.
Step 5: Filtering and Use.
After waiting for the brewing process to complete, you will need to filter the tea so that it will be able to be spread without clogging whatever it is you are using to get the tea to your plants. For this step, you will need to have another bucket, some type of fine mesh, I have an old pillow case for this, and something to support the mesh over the bucket while you pour the tea through it. This will take some time, and you will have to clean the mesh a few times, as there is a lot of dissolved solids in this mixture. It would actually be best to have several pieces of mesh on hand to get this part done as quickly as possible. What you will end up with two things, the first being the tea that you were trying to make and the compost on the bottom of your brewing bucket. The compost left in the bucket has done its job and can just be poured out into your garden just as you would any type of fertilizer. The tea can be spread by any means that you would spread a traditional liquid fertilizer. The only real precaution that you need to take is that if you decide to spray the tea onto edible plant parts, then make sure that you thoroughly wash these plants before you eat them. Other then that, the tea is a truly universal fertilizer that you should get excellent results from.