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Mold and Algae on your Aerogarden Sponges & Other Growing Substrates

Ew, I Found Green Mold On My Seeds and Aerogarden Sponges! What Does It Mean?

We get it; the presence of white fuzzy stuff is rarely a pleasant surprise for gardeners and plant owners. But before you go throwing everything out and starting over, allow us to present the case FOR it. Often misunderstood, mold offers some surprising benefits to your plant health and is not nearly as harmful as it might look. 

Within the Urban Leaf product range, mold has been known to occur on our AeroGarden compatible grow sponges (most common), and occasionally on our Bottle Garden kits, Soil Based kits and Herb Starter Kit. What all of these products have in common is that they all include some sort of growing medium (or “Smart Soil”) that is used for germinating seeds. This growing medium is made from materials that include coco coir, peat moss and composted fir bark. 

What Exactly Is Garden Mold?

‘Mold’ is part of the fungus family, and consists of millions of small organisms that can appear white, black, orange, green or purple. Mold exists pretty much everywhere – indoors and out – and whether you realize it or not you are encountering it every single day of your life. 

The type of mold that you are most likely to encounter on (or in) indoor gardening products is called Tricoderma. Plenty of information can be gleaned from the testing report which was completed by an independent laboratory. Here are the rest of the details about it:

  • Kingdom: Fungi
  • Division: Ascomycota
  • Subdivision: Pezizomycotina
  • Class: Sordariomycetes
  • Order: Hypocreales
  • Family: Hypocreaceae
  • Genus: Trichoderma

Tricoderma is actually an incredibly beneficial ally to your gardening. It reduces Pythium, Fusarium, and Rhizoctonia. Some gardeners will actually deliberately inoculate it due to the many benefits it offers – especially during the root development stages of the plant’s life. 

How Can You Prevent Mold?

Understanding how to prevent mold on your growing substrate is as simple as understanding what it needs to grow and thrive. Mold tends to thrive in environments that are damp and warm – including packages of hydroponic grow sponges that are shipped during summer months in closed containers (i.e. our products!). 

If you want to prevent the mold, then we recommend either reducing temperatures, moisture levels, or both. Prior to packaging, we do air-dry our plugs on large racks in an effort to reduce the chances of a Tricoderma bloom (not because it’s bad, but because it tends to induce a 1-star review!), and if you don’t like the look of it we recommend you store yours in a cool dry place. 

How Can You Start with Mold Removal in your Hydroponics System?

The easiest way to start with mold removal in your hydroponics system is to physically agitate it. If the hydroponic grow sponges are still in a bag, you can just mix them up or shake the bag. If that’s not an option, simply brushing it off will do the same thing. 

The benefit of this approach is that you will remove the visible signs of the mold on the surface of your plug while retaining the root-protecting beneficial fungi within the plugs themselves. Win-win. 

Is Putting Hydrogen Peroxide on Your Aerogarden Sponges Safe?

Other retailers and distributors of similar products treat their products with hydrogen peroxide. Technically putting hydrogen peroxide on your aerogarden sponges is safe, and it is effective at killing all the fungi (both good and bad). Since you are going to be eating food grown in these plugs, we prefer to keep the Tricoderma in and the chemicals out. But if you would like to treat your own plugs with hydrogen peroxide then go for it – this is cheap and readily available and can be applied with a spray gun or mister.

It’s Not Mold, It’s Algae On Your Coco Coir Aerogarden Sponges 

What is Algae & How Is It Different From Mold?

Algae is a type of plant, not a fungi. Algae is a simple, nonflowering, and typically aquatic plant of a large group that includes the seaweeds and many single-celled forms. Algae contain chlorophyll but lack true stems, roots, leaves, and vascular tissue.

How Can You Prevent Algae in Coco Coir Aerogarden Sponges?

The same conditions that make our grow sponges a great place for seed germination, also make them a great environment for algae. Algae, as a type of plant, requires the same inputs that plants do to thrive, including 1) light, 2) water and 3) nutrients. When all three are present, the environment is ripe for both plants and algae.

In order to prevent algae in your coco coir sponges, we need to remove one of these three inputs. Since we’re talking about hydroponics mold and the root zone of the plants, taking out the water and nutrients isn’t really an option. The approach we recommend therefore is to remove the light. This can be achieved by placing some sort of light-shield around the base or stem of the plant – which could be as simple as a round piece of paper or cardboard with a hole in the middle for the stem of the plant to fit through. 

If you’re looking for a budget and eco-friendly replacement for your AeroGarden pods, try out our AeroGarden Compatible Grow Sponges which go really well with our dwarf seed varieties. And if all this mold-talk has got you second-guessing – don’t worry, we won’t leave your plants out to rot! We offer a Green Thumb Guarantee where you can get a replacement or refund for your purchased product.

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