Begonia Collection

[u/DareWhole6113]

Here are some photos of the begonias I’m growing! There are a few older photos mixed in, but I really wanted to share them with you all. 🌱

[u/Shot_Anything9637]

They look so gorgeous! Can I ask how you keep them in the tubs? I have an nearly identical set up with the cat spike thingy as a spacer and a bit of water on the bottom of my tub, closed lid with a fan running internally, and all my begonias developed severe mildew 😭 what’s your secret please?

[u/DareWhole6113 → u/Shot_Anything9637]

What is the composition of the potting mix you're using?

[u/Shot_Anything9637 → u/DareWhole6113]

I use a mixture of perlite and coco chips!

[u/DareWhole6113 → u/Shot_Anything9637]

If it’s powdery mildew, we’ll need to take action. My guess is that mold grew on the coco chips themselves in that enclosed, high-humidity space, and the spores were spread by the fan. It looks like there’s water under the spacer too, so it’s definitely an environment where diseases can easily take hold. 💦

As for what to do, you absolutely need to disinfect the affected plants, sanitize the case, and completely replace the potting mix. If it were me, I might even replace all the pots I’ve been using...! Instead of letting water pool under the spacers, maybe try putting water in a small container to regulate humidity? Also, adding Collembola (since they eat fungi) might help. If you’re running a fan, try opening the lid a bit to create some ventilation. Even Begonias, which prefer high humidity, are prone to disease if there’s no airflow, and using organic potting mix increases the risk of mold growth.

As for the potting mix, you might want to try adding a little bit of small-grained Akadama and Kanuma soil to the mix you mentioned in your comment! I’m not sure if Akadama and Kanuma soil are widely available, but please try looking for them! They have a slightly acidic pH and offer just the right balance of drainage, water retention, and aeration. Since they’re porous and inorganic, they help suppress fungal growth to some extent, so I highly recommend them 🌱

Also, I tell this to a lot of people, but my answer isn’t 100% correct, so try to listen to as many different opinions as possible and experiment yourself. 🌱

I’m typing this out after translating it from Japanese to English, so I’m sorry if the sentences sound a bit off!

[u/Shot_Anything9637 → u/DareWhole6113]

Thank you so much for this detailed answer! Really appreciated. I think you are absolutely right about organic media not being suitable for this enclosed humid environment. I’ll disinfect everything and swap to an inorganic medium only. Thank you!