Biofilm – Your Questions Answered and More

Although many growers will reach for the hydrogen peroxide at the mere mention of biofilm, it’s not always cause for concern. In fact, some biofilms are beneficial to your garden and eliminating these too often can prevent peak nutrient uptake and cause permanent damage to underdeveloped root systems.

So, how do we know when to love it and when to leave it (and by leave it, we mean kill it off entirely)?

The short answer is if you’re not experiencing symptoms of pythium (or other root diseases), you can leave any biofilm you see alone.

The long answer needs a little more explaining, so we’ll start with what biofilm is.

Put simply, a biofilm is a colony of microorganisms that usually begin their lives within our common water supplies. These microorganisms are free-flowing, and really, they’re just looking for a place to settle down.

Microorganisms aren’t picky about where that place is (quantity over quality for these guys) and are known to make a home out of just about anything.

They enter your system with your nutrient solution and attach themselves to plant roots, growing media, growing containers and everything in between until a biofilm is formed. Then, when the area has been colonised, some of these microorganisms will detach themselves in search of another spot, where they will do the same thing all over again.

It’s easy to understand how biofilm spreads so quickly, especially when you consider that they’re mostly invisible to us. A biofilm will only become apparent after it’s been in your system for weeks or even months.

The problem growers have with biofilm is that they can be made up of either beneficial or harmful microorganisms. When you’re unlucky enough to get the latter, it can be devastating to your system.

In particular, we’re referring to pythium, a parasitic, fungus-like microorganism and the primary perpetrator of root rot.

Early telltale signs of a pythium infestation include changes to the texture of your plant’s root system or an off, rotten egg-like smell coming from your nutrient solution.

Later signs of the same infestation include stunted plant growth, yellowing foliage and leaf drop. If the disease is this far along, your plant is unlikely to survive. Whether you have noticed early or late signs of pythium, you should take action straight away.

Here’s how:

Firstly, remove the affected plants. If you’ve noticed early signs, you can try and save the plants by transferring them to another growing container. If you choose to do this, make sure you keep each plant separate to avoid infecting otherwise healthy plants.

If you’ve noticed some of the later signs, you should get rid of the affected plants and again quarantine any that may be infected but are not yet showing symptoms.

Next, you need to really deep clean your system.

Start by cleaning each element of your system with soapy water and a brush. Using a harder brush is ideal, as you’re aiming to dislodge the infestation physically. Be careful not to use something too abrasive (like a scourer) as a system with scratches just gives future infestations a better shot at hiding.

If there are elements in your system that cannot be scrubbed down properly, you should replace them.

Next, sterilise your system. We like to do this with a product called Oxy-Plus but you can use any form of hydrogen peroxide available to you.

After you have disinfected your system, give the whole thing a rinse out with clean water. If you are replanting something young, you’ll need to do this last step multiple times as higher disinfectant doses can harm underdeveloped root systems.

You can now replant in your system – make sure you’re using new grow media and fresh nutrient solution.

Preventing pythium outbreaks in your system is mostly about keeping your plants strong and healthy, so it’s easier for them to fight off disease themselves. If you’re still worried about repeat outbreaks, there are a few things you can do, such as:

• Make sure you keep your reservoir sufficiently oxygenated
• Add a product like CANNA Cannazym to your system
• Keep your grow room cool

And that’s it, another newsletter done and dusted. Hopefully you enjoyed reading and maybe you even learnt something. As always, happy growing!