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WeedBMstarted grow question 1mo ago
Hello friends, I’m having this problem with all my grows — when they reach 15 days old, the lower leaves start to yellow and the tips dry out. VPD is okay, EC 1.0, 27°C, coco fiber with perlite
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MrGrowDiarieanswered grow question 1mo ago
Hey! That yellowing and drying of lower leaf tips around day 15 can be caused by a few common issues, especially in coco with perlite:
1. Nitrogen Deficiency:
Lower leaves yellow first when plants need more nitrogen. EC 1.0 might be a bit low depending on the stage and strain, especially in coco where nutrients flush through quickly.
2. pH Issues:
Check your runoff pH—coco likes around 5.8-6.2. If pH is off, nutrient lockout can cause yellowing even if EC looks fine.
3. Watering or Root Issues:
Over- or underwatering can stress roots and cause symptoms like yellowing tips.
4. Salt Buildup:
Even with coco, salts can build up and cause tip burn. A light flush might help.
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What to try:
Slightly increase nitrogen in your feed.
Measure runoff pH to make sure it’s in range.
Make sure watering schedule isn’t too frequent or too heavy.
Flush lightly if you suspect salt buildup.
Check roots for any signs of rot or stress.
MistaOCanswered grow question 1mo ago
If you’re consistently running into issues around day 15, that strongly suggests the beginning of a nutrient deficiency. This is especially common when growing in coco substrate. If you’re using coco, it’s important to start light feeding from day 1.
One of the most critical factors is the pH level of your irrigation water. Coco doesn’t buffer pH on its own, so you must maintain it at around 5.8 consistently.
As mentioned, early fertilization is key. If the lower leaves start yellowing first, it’s very likely a nitrogen deficiency at this stage of growth. Calcium and magnesium are also in demand and need to be added as well.
An EC value of 1 might actually be a bit too high for this phase, and that could be contributing to the issue.
Also, consider transplanting your plants into larger pots soon. If they’re around 15 days old now, this would likely be a good time to do it.
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Nocone_Purpleanswered grow question 1mo ago
This issue sounds like early-stage nutrient deficiency, likely nitrogen or calcium/magnesium, which is common in coco if not supplemented properly.
Even with EC 1.0, coco tends to leach calcium and magnesium, so unless you're adding CalMag, deficiencies often show around day 10–15.
Simple fix in one line:
Add CalMag and slightly boost nitrogen early on coco needs support from day one to prevent yellowing at 15 days.
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John_Krameranswered grow question 1mo ago
don't let it dry and keep 0.5 EC
1 is to much
also lower C if u can and keep 7-12k lux
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