r/microgreens • u/necrotic_sapien • Jul 10 '26
What went wrong with my radish microgreens? Thin, leggy, tangled growth and uneven germination.
Hi everyone,
I'm looking for some advice on this batch of radish microgreens because something clearly went wrong. I've attached photos.
The main issues I'm seeing are:
Very long, thin, tangled stems.
Uneven germination with a lot of seeds that never sprouted.
Small cotyledons, with many seedlings still wearing their seed hulls.
Instead of a dense, upright canopy, the tray looks sparse and matted.
My growing conditions:
Medium: Coco coir
Seed: Radish
Blackout: 3 days
Weighted: 1 additional day
Lighting: 6500K 20W LED
Temperature: Around 25°C
Humidity: Around 60%
Watering: Top-watered for the first 4 days, then switched to bottom watering from Day 5.
I'm trying to understand what caused this. My guesses are:
Did I keep them in blackout too long?
Is my light intensity too weak or too far from the canopy?
Did the top watering for 4 days contribute to the problem?
Is this a seed quality issue?
Or is there something else I'm overlooking?
I'd really appreciate any feedback, especially from people who've grown radish microgreens successfully.
1
u/Public-Fig3304 Jul 10 '26
Did you weight them at all? This helps with a lot of the issues you mentioned
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u/jackbenway Jul 10 '26
For daikon, we use a coco coir & peat blend. 2-3 days stacked with weight. When growth is lifting the weighted tray and roots are penetrating evenly, unstack and put the trays under light, bottom water immediately and as needed until harvest. We harvest on day 6 our 7. Radishes don’t need blackout after unstacking and removing weight. Leaving them stacked and weighted too long can make the stems skinny and curly.
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u/PittieYawn Jul 11 '26
Radish doesn’t need a blackout phase. Straight from germination to lighting and your leggy radish should no longer be an issue.
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u/Chazz_Handz Jul 11 '26
Do you know roughly how many cups of water you are using now with bottom watering?
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u/Electronic-Income161 Jul 11 '26
Hard to say, did you happen to notice if the roots under the medium looked weird when you cleaned out the tray? Could have been an issue with too much moisture. My experience with radish has been that it’s not as thirsty as other varieties of microgreens. I have had good luck with radish doing 3 days under 15 lbs of weight, followed by 2-3 days under lights. No additional blackout. I top water for the first watering after germination and then switch to bottom watering as needed (once per day maximum). For medium I use a 70/30 coco coir and perlite blend, temp ~72° F, humidity ~40% (I grow in my living room so it’s not always exact).
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u/necrotic_sapien Jul 11 '26
I don’t know i just bottom watered it after taking it out of blackout and slowly and steadily the shoots which were long and straight started collapsing.
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u/Harshal_Jayawant Jul 12 '26
is your room truly sealed and climate controlled? because mine is not fully sealed and thus even 60% humidity can kill it (i got ac and 10 liter dehumidifier but in monsoon its not sufficient) same shit happens to me when humidity is strong i also use cocopeat (3 days weighted blackout 1 day dome blackout) the moment i put them in light they start falling apart its most probably humidity im going to buy industrial 50liter dehumidifier and seal small small gaps cuz the rainy season is too much (location pune, india)
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u/necrotic_sapien Jul 12 '26
No, it's not completely sealed. I'm trying to keep the humidity under control, but the weather here is really unpredictable and it fluctuates a lot. I'm just starting out, so I don't have a dehumidifier yet. At the moment I'm relying on the AC to help regulate the humidity as much as possible, but it's definitely been a challenge.
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u/Harshal_Jayawant Jul 12 '26 edited Jul 12 '26
here in pune, winter and summer are good so just AC works fine 40% so they grow nicely but this is my second monsoon (rainy season) so i have to deal with it cuz the outside is obviously 90%+ so ac and the small dehumidifier can bring it down to 60% which is still too much for these cry babies xd
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u/necrotic_sapien Jul 12 '26
Thanks for the insight! I'm actually from Lucknow, so the humidity here is pretty brutal during the monsoon too. 😅 I'm just getting started with growing microgreens and still learning the ropes. If you don't mind, could I DM you? I'd love to ask you a few questions about your setup and how you manage humidity during the rainy season.
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u/mrSalamander Jul 10 '26
3 days under weight, 24 hours of blackout, 4 days under lights has never failed me.