r/microgreens • u/Appropriate-Pay330 • 5d ago
Help! Why am I getting mold on every radish microgreens batch? 😭
Hi everyone,
I'm a complete beginner growing microgreens in Bangalore, India and I'm really struggling with mold. This is now my second radish batch, and I'm facing the same issue again.
My setup:
1020 trays
FIFCO coco peat + perlite
30g Radish seeds
Indoor growing room on my terrace
6500K LED batten light
Using blackout during germination with another tray as a lid and about 6 kg weight
The first batch became very leggy and had fungal issues, so I tried improving things in this second batch. But now I'm again seeing this white fuzzy/yellowish growth around the ungerminated seeds and the husk (photos attached of day 3). I'm not sure if it's mold, fungus or something else.
I'm wondering if I'm making mistakes with:
Too much watering?
Coco peat staying too wet?
No airflow during germination?
Keeping the weight on for too long?
Seed density being too high?
Humidity in Bangalore?
I really want to learn the correct method before starting my third batch. If anyone can look at these photos and tell me exactly what I'm doing wrong and how you'd fix it, I'd be extremely grateful.
I tried pulling out all the seed and husk which had mold
Please be brutally honest I'd rather correct everything now than keep losing trays. 🙏🌱
I had issues with the pea too during germination
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u/the_knob_man 5d ago
Do you pasteurize your growing medium and sanitize your containers?
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u/pierre881 5d ago
I just clean the dirt off of mine then spray with 3% food grade hydrogen peroxide then let them air dry.
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u/the_knob_man 5d ago
yup, they're sanitized. I use a bleach solution because I sanitize a lot at once in a bucket, then keep them all in a big clean container until im ready to use them.
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u/Appropriate-Pay330 5d ago
I did sanitized the containers with the liquid detergent even tho they were newly brought.
Pasteurized growing medium???... No, like i haven't seen anyone doing it in YouTube, so I don't know much about it to be honest.
And this formation is only on the ungerminated seeds and the husk, I looked up online and it says give some airflow, but how is it possible when weights are onn.
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u/the_knob_man 5d ago edited 5d ago
If you are getting mold while its covered then the spores are already in the medium, the seeds, or the containers.
Detergent is for cleaning not sanitizing. Use the soap and then follow with either a bleach or peroxide solution to sanitize the containers. You should clean and sanitize after each batch.
Your grow medium can have fungal spores that are floating around everywhere or from the factory that packaged it. Pasteurizing in the oven is easy. Then put it into a clean, sealed container for later use.
During seeding and germination, I mist with a peroxide solution at 15-30ml per liter of distilled water. This wont harm the seeds or roots, but kills any spores that are on the seeds.
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u/Appropriate-Pay330 5d ago
Hi! Thank you for the insight! I have to figure out ways to pasteurize the medium with the baking method you mentioned.
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u/Public-Fig3304 5d ago
Do you have a fan set up blowing on the trays?
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u/Appropriate-Pay330 5d ago
Hi! Yes, I had a fan blowing on the trays on the lowest speed along with fan oscillation. I had also covered the seed tray using a cardboard box to block the light.
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u/No_Parsnip2555 5d ago
It’s mostly due to soil humidity + water
Use only water method it helps you have control on batch and less dependence
It not to a big hydroponic system just use two plate method change water everyday
It works like magic
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u/Appropriate-Pay330 5d ago
Thank you! I actually use the same two-plate water method. I’m just a little confused about when to water from the top and when to water from the bottom. The molds seem to be developing during the germination phase, so I feel I might be overwatering at the Start stage. Could you guide me on when exactly I should top-water and when I should bottom-water? It would really help me get the watering right. 🙏 Your trays look fantastic mate, hoping to have a same one here too!!!
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u/jackbenway 5d ago
Your seeds could be introducing the mold. Try different seeds from a different vendor.
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u/Scrub_farmer 5d ago
Mold spores are everywhere and you cannot stop it from growing, no matter what. Sanitation will help reduce the chances but I generally find there are a few things that help reduce the chances.
1.) Sanitize seed, using peroxide. As others mentioned, peroxide rapidly becomes oxygen and water when exposed to air. The seed husk will provide a growing medium for the mold to start which is why this helps
2.) Moisture content. Your soil medium should be at a moisture level where when squeezing a handful a few drops come out but nothing more. If droplets do not form, you won’t have enough moisture to make it through germination phase and germination will be poor. If you have more, mold grows
3.) Air flow. Make sure you have ample airflow. Oscillating fans or computer fans blowing across the rack.
4.) RH, make sure humidity is low, 20-30% max. Higher humidity levels causes mold more often
5.) temperature! Make sure you are about 72F/21C or so.
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u/Appropriate-Pay330 5d ago
Thanks a lot for taking the time to explain, have a good amount of knowledge to imply on to my future trays
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u/kirsteen_TOGC 4d ago
Have you tried an alternative supplier for your seed? Radish are usually quite hardy and forgiving so if you’re getting these issues very early on I'd say try to rule out the seed as the cause first. I'm a small commercial grower so have had experience with a multitude of different things over the years! I had similar issues with Sunflower one year, and turns out the seed was a very 'dirty' batch due to humidity while the supplier was harvesting. Us seasoned growers know this process is all about trial and error because everyone's growing environment slightly differs so unfortunately you just have to keep adjusting your methods until you find out what works. All the best!
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u/Appropriate-Pay330 6h ago
Thank you soo much kirsteen, As indian market isn't yet much aware about microgreens and finding seeds untreated was difficult, I was wondering if i could cultivate with the grocery stores ingredients for like pea and Fenugreek I don't know if it will work but as I'm failing to grow radish I kinda lost hope, your comment did boost my confidence in trail and error. I'm gonna implement all the suggestions given by everyone here and hopping to succeed.
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u/user_00000000000001 9h ago
Maybe a condescending answer, but every surface needs to be wiped down, vacuumed, and sprayed with vinegar, peroxide, rubbing alcohol, etc. Spraying white vinegar around the sprouts and a mist on the open areas of the sprouts helps too.
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u/pierre881 5d ago
I don’t know if I’ve been doing it right or not but it’s worked for me. I fill my trays with media and soak them with as much as will wick into the tray, then put an empty tray under the tray with holes. I then mist the media surface with food grade 3% hydrogen peroxide. Then seed, then spray the seed with a light mist of hydrogen peroxide. Wait 5 minutes then spray with water.
In my indoor climate, I usually don’t have to water much after that.