Well now that this question has been brought up on a national level, and it seems that people are starting to “choose” sides, I wanted to weigh in, and discuss this topic a little further.
Firstly, both sides are “right” with the reasons they either say to use or not to use a cover crop.
Let's discuss the pro's and con's of both, and then delve deeper into what may work for your garden.
The anti-cover crop argument seems to be that a cover crop is a vector that can bring in pest, and disease. They aren't wrong. Cover crops do indeed need to be managed like any other crop and too many times we see customers not doing this and then they get some sort of pest issue. I would say the number one thing we see pest issues in is clover, but they are not limited to just clover.
The rational would be then to not use cover crop, and it will reduce you pest pressure. Again, they aren't wrong. If there is less plant material then there is less worry of pest pressure, and you can focus on your cash crop instead of a cover crop.
At scale, the argument against cover crops also comes down to the time and money it takes to treat the cover crop just like your cash crop. You have to implement an IPM strategy in your cover crop to be successful. This will take more man hours, and more input costs versus just cutting out the cover crop.
Well already to me the anti-cover crop group makes some very valid points. Almost so valid that I could be swayed to not use cover crop.
Why you should use cover crops in a no-till soil
So we have the con's which are all very valid, but what about the benefits? Do the benefits not out-way the con's?
The first benefit that comes to my mind when using cover crops is polyculture. If you are growing hydro indoors you give two fucks about what mother nature does, but I thought the entire point of no-till living soil was to try to bring the outside indoors?
Cover crops can be sown for many different reasons. If they are only there for the sole purpose of companion planting that seems to be a solid reason. Studies show, and have for decades, that plants are happier around other plants. There is a symbioses between them and they can share many beneficial aspects that the other may not possess.
In cannabis cultivation terps are what we as living soil growers are trying to increase. There are plants that may increase resin production in plants that are planted with them. So the simple act of companion planting these plants may increase your resin production. That seems like a win.
Thinking about the soil we can also discuss plants that may help the physical properties of the soil. Over time compaction can be an issue, and planting certain plants can help to keep your soil aerated. If you plan to run your soil for multiple years, you will need to plant cover crops that will shoot down long deep roots to help fight compaction in your pots or beds.
Exposed soil also will dry out, and can harden. If you keep a low cover crop on it, then it will protect the rays of the sun or grow lights from beating down on the exposed soil. It will also allow water to slowly penetrate the soil instead of hitting the dried out top and running off. This can be achieved with grasses, as well as many other types of cover crops.
I fall on the side that cover crops are indeed worth the extra work. I do understand though why others want to cut them out.
In a small scale home grow cover crops are a no-brainer. I would always suggest for you to plant a cover crop in your home grow. It will not really add much time or money to your garden, and will bring an overall health to your soil and cannabis.
As you scale up you will have to decide if you want to use a cover crop that may be a vector for pests and disease. That's for you to decide and no one else.
There are other things that I would first focus on before I decided to remove cover crops.
Building a decontamination room so that all employees are as clean as possible before they enter the facility. Since humans seem to be one of the biggest vectors in a garden, that seems like the logical first place to start.
Adding routine cleaning in your SOP, changing out air filters regularly, washing hands, etc.. all seem like a great place to start when we are speaking about vectors. Not bringing in outside clones also seem like a no-brainer, but should be standard in all grows.
After implementing all of these things if you still think your cover crop is a vector worth removing, go for it. Don't let me or anyone else tell you what to do in your garden. There is not one answer that will fit all situations. Do what you feel is best for your plants, and your garden.
There are always going to be pro's and con's to everything you do, it's up to you to decide if the pro's out-weigh the con's. To me, in most instances, the pro's of cover cropping outweigh the con's. Make note I said, “in most instances”, because again, there is not ever one all encompassing answer to any question.