Understanding Nitrogen

[CHELSEA_SMOKERS_SOCIETY]

So,

After Many many years of outdoor soil in pot growing ive come to expect that all the main fan leaves will yellow and fall off diring flowering. Recently i found out that this is actually a nitrogen deficiency, as flowering uses up loads of nitrogen and thus the pot of compost that the plant lives in is drained. The buds are perfectly good. Ive had great and shite harvests with this laissez-faire method, and on top, I have always boasted that my grows use no fertiliser and are 100% organic etc.

However having recently joined the world of indoor grows, i am wondering about these almost skeletal but budding nicely plants.

If i was to add some nitrogen food to them to keep the fan leaves during flowering....

A) is this actually necessary? Have the fan keaves done their job in vegging, or do they still help in flowering too?

B) how much to give and whats a good brand of nitrogen fert?

Sorry if this is too vague and broad a question, ive never really given fert. any thought before beyond the potting up stages.

Cheers

[Uncle Ron]

Welcome to the wonderful world of indoor growing, may I offer you some delicious hydroponically grown bud?
In all of my indoor grows, I have used nutrients from Bio Bizz, B' Cuzz, and Advanced Hydroponics of Holland, no experience with using individually produced or raw materials.
From my studies of the three mobile elements (N-P-K), Phosphorus is the key element during flowering, while Nitrogen and Potassium are secondary.
I've witnessed leaves turning yellow, and the causes of the Nitrogen deficiency were underfeeding, nutrient lockout, and withholding nutrients during the flush.
My suggestion - research the companies above and others, see what they have to offer for nutrients during flowering.
Happy farming...

[davehaze]

Well nitrogen in flowering is one of those topics that many growers disagree on, imho veg nutes should be used for the first 2 weeks of flower at least. I don't want to see fan leaves start to yellow until at least week 6 of an 8 week strain.

[Uncle Ron]

Well nitrogen in flowering is one of those topics that many growers disagree on, imho veg nutes should be used for the first 2 weeks of flower at least. I don't want to see fan leaves start to yellow until at least week 6 of an 8 week strain.

I agree, many opinions for and against.
My take, give the plant what it needs, all things considered (ex. flushing).
During flowering, giving plants nutrients and minerals typically used during veg won't harm the plants, the plant won't revert from flowering to veg, but there is at least one caveat - overfeeding (nutrient burn anyone?).
If one were wanting to give these nutrients during the flowering period, I would suggest using 25% of the recommended amount for veg, then adjust as necessary (plant reaction in a day or three).
Happy farming...
...

[davehaze]

Well if you have been feeding veg nutes at a certain strength and the plants are fine then it won't suddenly cause nute burn.

[Uncle Ron]

Well if you have been feeding veg nutes at a certain strength and the plants are fine then it won't suddenly cause nute burn.

Uhm, that's correct. Stating the obvious maybe...
I use Advanced Hydroponics of Holland nutrient line, and if I maintained the level of Grow Nutrient throughout the entire grow, I would kill the plants. There is a reason why the manufacturer recommends decreasing the Grow nutrient to zero while increasing the Bloom and other nutrients - because it was designed to be balanced at those ratios.
If I was growing a strain that was known to yellow (nitrogen def), I would continue the use of the Grow nutrient but at 25% strenght. This minimal(?) amount may be sufficient, or it might not be enough. As long as the plant doesn't show any signs of nutrient burn (one day, three days, five days, a week or more, whenever), keep rockin' the garden. If the fan leaves begin to yellow, increase to 50% and observe. I also continuously check the pH and EC. If the plants show signs of nute burn, I flush and start over but at a reduced amount. Not difficult, but it can be a pain when trying to dial in nutrients, pH, EC, water temp, etc... when growing unfamiliar strains.
Another great reason to grow from clone is knowing what to expect.
Happy farming...
...

[davehaze]

Well most people overfeed even if there is no sign of burning. I veg at EC1 and flower at EC1.2-1.4.

[USbongLord]

FLORANOVA ....I'm done

[Uncle Ron]

Well most people overfeed even if there is no sign of burning. I veg at EC1 and flower at EC1.2-1.4.

A great reason to invest in a pH/EC meter; minimizes watering and feeding mistakes, at least ones I've made.
Using Advanced Hydroponics and their feeding schedule, the veg mixture has an EC of 0.98, and the flowering about 1.3-1.4.
After a couple of days, the EC will have risen to 2.1-2.2, and a one time spike to 2.8, which caused minor burns on a couple of leaves. A quick flush and all is well...
Topping off the reservoir with nutrient mix drops the EC to 1.7-1.8, but this is only good for about 10 days. The EC will raise and remain above 2.0 unless I dilute with clear water. I drain and refill the reservoir, and flush the plants with clear water, every 10-14 days. This also helps with clearing built-up residual salts as well.
Happy farming...
...

[SatoriKarma]

After Many many years of outdoor soil in pot growing ive come to expect that all the main fan leaves will yellow and fall off diring flowering. Recently i found out that this is actually a nitrogen deficiency, as flowering uses up loads of nitrogen and thus the pot of compost that the plant lives in is drained.

Sort of! You're on the right lines.

It's actually the vegetative stage that uses all the Nitrogen. Nitrogen is the primary nutrient for the chlorophyll in the leaves that keeps them nice and green. As the N gets used up in vegetative growth and because you can't ideally repot in flowering the chlorophyll disappears from the fan leaves turning them yellow. The plant mostly uses Phosphorus and Potassium in the flowering stage, not Nitrogen.

One way of minimising this is to repot regularly in Vegetative stage, which not only gives the plant a new supply of nutrients it also helps to form the rootball for maximum nutrient uptake. You should ideally do one final repot into a decent sized pot just before 12/12, which should contain all the nutrients the plant needs to end flowering.

In my experience, it's best to try and avoid feeding nutrients if you can (in organic soil) particularly towards the end of flowering as you want the plant to empty itself of those nutrients before harvest. But I accept not everyone agrees with this philosophy.