Help with growing issues

Hi everyone, I need help.

Im in week 6 of flowering and my plants are turning yellow at the tips of the leaves with some yellowing of the larger leaves. Everything has gone well up to this point, but I’m concerned and not sure what to do.

Any help would be appreciated

Thank you in advance

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They are in a grow tent in 5 galon canvas pots and I use ph perfect. (Grow, micro and bloom) i water when the moisturiser level reaches 20% then give them 1 litre of water. But I think as I don’t get any run off I need to increase to 1.5 litres. The plants are going yellow on the tips of the leaves and larger leaves are allso starting to go yellow. I have just flushed them with 2 litres of plain bottled water hoping that will fix the problem.

Hi,

If yellowing starts from the bottom on the old leaves, it’s a nitrogen deficiency.

If it starts at the top, it’s a CalMag deficiency.

Yellow leaf tips can indicate too much nitrogen or overwatering. You want less nitrogen during flowering anyway.
Since neither is likely the case for you, I’d guess it’s your pH level. Or an imbalance in the CalMag ratio.

I’ve brought this up in another topic before.
If the tap water, for example, already has a ratio of 6:1 and you pour a ready-made CalMag on top, which is usually in a 3:1 ratio, you introduce even more imbalance.

I had this problem for two years, always around the 3rd-4th week of flowering, and tried everything. More fertilizer, less, no fertilizer at all. Always the same result.

Often it’s also due to watering habits. In my experience, that’s the main issue for nutrient lockouts and deficiencies, which also depends on whether you’re growing organically or minerally.

My tip for you: Let the pots dry out well, spray everything moist, and keep pouring 250-500 ml in intervals every 10-15 minutes over an hour until you get 20-30% runoff at the bottom using water adjusted to pH 6.3-6.5.

Best regards

Thank you for the advice. I have used bottled water from day one and I’m feeding with ph perfect (grow, micro and bloom) and following the instructions on the bottle. This is my first attempt at growing.

Hey there! 5-gallon (~19 liters) pots are quite a topic! Something similar happened to us at first until we figured out the trick with the watering volume.

Just as a reference, with those same pots we realized that if you pour 1 or 1.5 liters, the soil barely notices and the entire bottom stays dry, accumulating salts. For ours, we are giving them 6 liters of watering and getting 1 liter of clean runoff out of it.

That liter of runoff is key because we measure it with an EC meter: if the runoff EC spikes (for example to 1900), you already know you need to dial back the feed intensity on the next watering and go in with a lower dose (around 30-50% of the schedule), allowing the plant to consume the excess without getting locked out.

If you do a flush with very little water, you don’t get anything out; you just end up waterlogging it and worsening the salt lockout. Try giving it a good watering with enough volume until it drains that liter, measure the runoff EC, and you’ll see how the plant starts recovering and feeding again. Good luck with that!