A common question I noticed around garden groups is how useful is it to get working with compost tea.
Is it good for your garden and plants? Should people go out of their way to brew it up?
Compost Tea For Plants
The basis of compost tea makes a lot of sense. The general idea is taking some compost and aerating it in a bucket of water. The nutrient will leech out a bit and then you have a liquid nutrient form of plant feed.
There are a lot of claims around compost tea such as it helps plants get nutrients better or faster and that it gives more nutrition than just composting.
I decided to do a deep dive on what is known about compost tea. I have without a doubt noticed improved growth when watering weekly with leftover worm compost water that collects after I tend to my worm bins. I might even do a test grow so I can record the difference in how the plants look.
To be clear, this is usually waste water I use and the effects of the vermicompost would be the same if I put a bit of worm compost in each plant. Occasionally I will go out of my way to make compost tea because I don’t have enough vermicompost to spread to all the places I want a jolt of nutrition.
But what about compost tea in general?
Studying Compost Tea
One issue with trying to get to the bottom of compost tea is different people make compost tea differently. It isn’t one thing that is universal everywhere. This variety makes it hard to pin down the effectiveness unless you study a particular formula.
The stuff in my compost will be different than the stuff you put in your compost. Not to mention every crop of finished compost I make is going to be slightly different as some month when I get restaurant scrap I have an excess of carrot skin where a different week they have saved me some celery leaf in bulk this is even aside from whatever I’m pulling out of my kitchen.
Then if you study around at how people are making their compost tea it seems there are a bunch of different methods, some use a lot of aeration some don’t. Some use a water heater so the water is warmed and some don’t.
The issue when you are trying to make an educated scientific guess is you have to control for variables, but in the world of compost tea there isn’t a one method to rule them all.
In my own garden dealings I have noticed without a doubt the difference between when I use worm liquid versus just water. I get increased spurts of new growth on plants that were otherwise stalling in growth. Most noticeable in neglected houseplants.
Now I should also add that the benefits I get from using the precious worm liquid seems to also happen when I add a few spoonfuls of the solid compost as well.
Nutrient Levels
Common knowledge is that compost is nutrient rich and is also chock full of water-soluable nutrients. When water is passed through compost you get a very diluted mish mash of nutrient.
When compost is turned into compost tea you don’t increase the level of nutrient you draw out of the compost unless you add a capful of some sort of outside product. If you are doing all that anyway why bother going out of your way to make special liquids?
Being in liquid form is no different than putting a smattering of compost and watering by my estimation.
The only thing that gives me pause is some people claiming compost tea properly made and with aerations can boost beneficial microbial activity in a superior way. When it comes to soil a lot of soil ecology comes down to the “living” aspects of the soil.
This is the only area that gives me pause as perhaps some food growing scientist can figure out the definitive answer.
From time to time you will find science articles like this one that show definitively beneficial affect of compost teas and the conclusion is different microbial concentrations seem to lend huge effect to the plant development.
Use Your Compost
In whatever form you nutrition your plants compost either as dry solid or tea is a useful boon to the garden. Either way the compost application will help make poor soil into a healthier living soil and help beef up the general soil ecology.
My take is I have noticed little difference in growth or plant health in already compost aged beds that I would class as already high quality soil. If you are going through the steps to compost, mulch, and add back to your soil it might be completely unnecessary to really worry about.
Microorganisms
Again to reiterate the above, my only pause in completely discounting any sort of “necessary” use of compost tea has to do with preferred microorganism propagation.
We know that will soil there are harmful microorganisms and highly beneficial ones that supercharge plants. According to the above study linked the type of compost turned into compost tea does matter and directly affect plant resilience.
Perhaps in the future to come we will lock down a preferred way to help promote more beneficial organisms and proof that making a compost tea is the preferred way to cultivate and deliver.
Vermicompost Foliar Spray
When it comes to compost liquid one I’m been employing a long while is the leftover juice from my worm bins. There has been research indicating a net positive that it is an effective organic solution as a foliar spray that you apply to the plant leaves.
This application is something you can’t do with regular compost. The conclusion is that used as foliar spray the microbrial action can help fight disease for some types of problems.
Though other tests showed little or no improvement though not every “compost tea” was worm compost either.
End Conclusion
The overall impression that compost tea gives is that there could be some benefit and certainly nothing that hurts, but at present it is not worth the effort if you can spread the high quality compost you have on hand in solid form.
Though this is neglecting the bigger world of hydroponics which I have done on various occasion and used worm juice directly in an indoor tobacco grow when I was curious about natural pesticides. Though that growing experiment is more anecdotal and not a useful model for what I’m trying to explore.
There is a lot there that still needs to be studied in terms of work added. It definitely doesn’t hurt to have a little on hand for routine watering.
