Fan leaves falling off during flowering?

Personally three weeks into flower I would not apply nitrogen. Did that once andnit stunted my flowers.

 

I would agree mine look similar to yours. I feel like this sativa is taking forever to start getting dense. I gave them a nitrogen heavy fert as they started flowering to help growth, but too much nitrogen will promote more leaf growth then floral growth. Start just adding good clean water when the plant drys!
don't overwater and you will be great. I have heard many people say yellow fan leaves at the base towards the end of flowering is fine and it shows that the buds have used up the nutrients from the fan leaves which is good.

 

Do the leaves turn limp and droop prior to yellowing and going brown/crisp?

What strength are you feeding? What is recommended on the bottle?

Because that is a no-no. You need to start weak, like 1/4 strength, then work up to half what is recommended. It could be nute burn.

I'd suggest you use clean pH balanced water without nutes for a few times, then see if there is an improvement. The organic soil will have enough natural nutes in it to hold the plant. Just make sure you aren't giving it too much chemical at this point.

 

Or you could use a flush. If you havn't done one yet then you should, I do 3 flushes for soil grows, a small one in the mid of veg a norm one in mid of flower and a norm one 2 weeks from harvest. It could also be possible that your plants are not getting enough nutes, I may be mistakin but a 15-30-15 nute ratio is kind of off for flower, They usualy average to 1-2-2.

 

I'm going to guess that the ph dropped way low when you fertilized, the leaves look like a ph issue (curled under, spotty yellow). Take a better picture of the whole plant, and make sure that it is in focus.

 

Tap water contains some chemicals that certain plants are sensitive to, like chlorine. Now, tap water is perfectly fine to use, but you want to let it sit in the open for 24/hours prior to using it. This will allow the chemicals to dissipate. Leave it in a big bowl or bucket with an open lid.

You do need a pH tester. A lot of water can be quite high, like 8-8.5. (Especially city water. Even some bottled water is that high.) You really need to aim for 5.8-6.2.

Improper pH can impede the plants ability to absorb nutrients, among many other issues.

A $5-$10 liquid testing kit is all you need. [ame="http://www.amazon.com/General-Hydroponics-pH-Test-Kit/dp/B000BT32UA/ref=sr_1_1?ie=UTF8&qid=1315883278&sr=8-1"]General Hydroponics sells a nice one[/ame] that you can buy at most gardening centers.

General Hydroponics also makes a good pH Down solution, in crystal or liquid form. You need to get that, too. As an alternative, you could use vinegar to get your pH down, but it can build up salts in the soil if used for a long time. Don’t guesstimate with this stuff.

Your 5-30-5 nutes are fine, and ‘cheap’ does not mean ‘bad.’ Does it say, “micronutrients” on the bottle?

Just make sure you are using the nutes at the right concentration.

This is what I'd suggest for a plant with issues like yours:

Flush the plant with pH balanced water for a few times. That means, just water it until water starts dripping out the bottom of the pot, then stop. Leave it alone until the top 1” of the soil is dry. Then water again. I’d do this at least 3 times. It may take a few days, depending on your ambient heat and humidity.

Then start back up with the nutes at ¼ their recommended strength. No more. First add your nutes, then test, then add your pH Down. The nutes will lower the pH naturally by a little bit.

After a couple feedings like that, bump the nutes up slightly. Not too much! You want to gradually work your way to about half strength, then maybe push it a little higher if you feel the plant is responding well and not showing any droopy leafs or other nute-burn effects.

Water when the first top 1" of the soil feel dry.

That should save it, if it can be saved.

Cheers.

PS: Lighting
What spectrum are the lights in? 5600K, 2700K?
Keep the CFL bulbs about 2-3" away. 6" is too far.

 

You get 6.5 out of the tap? Lucky.

The water’s pH will change as it runs through the soil. Focus on what goes in.

 

You are burning your plant up with the nutrients. This is strong fertilizer and should only be used once a week or less frequently. It is ok for flowering, but you must use it with caution. You need to use clear water for a few watering and finish up the flowering using 1/2 strength once or twice more depending upon flowering period length. Two weeks before harvest stop ferts and use clear water to the finish.

Your purple stems are a Phosphorous deficiency caused by the high levels of Nitrogen locking out the P. You don't say what size the pot is, but 1 cup of water every 2-3 days is probably not enough water during flowering.

PW