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The never ending abuse of Phosphorous to enhance flowering

Smokin Moose

Fallen Cannabis Warrior
A common mistake for growers when they reach the flowering stage is to start hitting the plants with a high P fert like 10-60-10, continuing to use this blend exclusively, and when their plants start experiencing a deficit of N or micros as reflected by the dropping of lower leaves and chlorosis, they wonder why. Plants flower as a response to long nights, not because of fert blends high in P. A ratio of 10-60-10 is WAY to high in P. The plant will only take what it needs and compete for other elements that may be more important at the time.

You may have heard that too much N can inhibit flowering. No question about it, exclusive use of a plant food that is rich in N such as blood meal, a 5-1-1 blend, or ammonium nitrate may inhibit flowering especially if the phosphorous level is low, but most balanced blends have sufficient amount of P to do the job. Manufacturers/horticulturists will give you element analysis and what effect the elements have on plant growth, but remember this does not necessarily mean you will get better yields. Using a high P fert exclusively during flowering can actually work against you. It's an abundant amount of healthy leaves going into 12/12 that produce a lot of bud, not high P ferts.

I rotate fert blends as the plant *requires* them, not because it is "the thing to do." For example, when your plants are going thru the stretch phase during early flowering, they may need more N, especially if you're getting some yellowing in the lower/mid leaves. Give up the cannabis paradigms, and give them what they need. Go back to mild high P fert when the stretch ends, maintaining the foliage in a healthy state of growth until harvest for maximum yields. A 1-3-2 blend such as Peter's Pro Blossom Booster, 10-30-20, is one of the best flowering blends on the market because of several factors - it is higher in nitrate N and Mg. It is sold under the Jack's Classic label. An added benefit of Peter's blends is their use of high quality, very pure salts that will cut down on root burn.


New Member
thank you. im just getting ready to start my first indoor grow and that will help me very much. do u think if i jsut straight flush the plant during the whole flowering stage would do more harm or good to the buds. i dont want to load my plant with chem. but i know that it will need certin things to be a good harvest. but i figure if i juice it up enough while its in veg state that i wont neeed to when it flowers and the weed will taste great

Harry Red

Nug of the Month: Nov & Dec 2008, Mar 2009 - Plant of the Month: Oct 2008, Feb & May 2009
Rome420, you're gonna need to feed your plants during the flowering stage, which is normally around 70-80 days (give or take).

I think the point of this thread is that too much P doesn't really help and you still need N & K along the way.

You really need to pick out some good flowering/vegging nutes and follow the manufacturers feeding schedule for whatever brand you choose.

The person who posted this thread is no longer a member here but recommended flushing 3-4 days before harvest in soil, which sounds about right to me. Some people go two weeks with just H2O but I wouldn't want to starve my plants that long right at the end. Perhaps one week but no longer. jmo..




New Member
Harry dont you think its time you picked up the Growers Bible?Jason King and Soma also have great books if Jorge book doesn't have enuff out of the box thinking in it for you.


New Member
Your plant is dieing and don't need any nutes so a 2 week flush will not hurt your plant it will continue to die using up what water and nutes it can find but for the better taste of MJ let the plant suck up all the water it wants to get rid of the nutes. The grow bible is another good book to learn from.



New Member
hell yeah man, my plants fan leaves, 4 weeks into flowering, have started to yellow and drop off and finally got them more nitrogen but not a whole lot. Is it normal for the hairs to start turning orange half way through flowering? Appreciate it


New Member
Hi rhodeo, I use FoxFarm products. They have a feeding schedule on line. And give good results. If your scared of overfeeding, just give them a 1/4 to 1/2 dose instead of the full dose!

Within Reason

New Member
Hello all!
I have started my first grow (indoors) the greenhouse is nearly finished (yeah!!!)
I have some questions if you folks wouldn't mind? First: What is a flush, and how is it accomplished? Second: what would you folks recomend as a vegging fert? (and) what is a good flowering fert? My only fert experience is with miracle grow.

I know I'm a ways away from from needing these but I like to prepare for the next phase. I'm an amature home gardener who has been forced to build a greenhouse due to the local cats, squirrels and birds destroying my garden every year...Not this year!!!

One of my specialties is growing a screamin salsa garden (and roses...lol) but I have finally gathered the nerve to grow some special herb ;) since I now have a good sized greenhouse at my beck and call!

Any help and or advice you brothers and sisters would care to impart to me would be seriously appreciated! Growing MJ is totally new for me...everything else no problem lol. But MJ?...Oh boy I might need some help. So I am asking for assistance.

Thank you so very much for your valuable time...


Within Reason

New Member
Please excuse the add on post here.
I forgot to ask...just what is earth juice, and can I use it in a soil application?
Again thank you very much for your help and patience.



New Member
most MG is time release which means you have no control over the amount of nutes your plant is getting. I also dont think you need that much nitrogen during flower unless you want your girls to stretch. 15-30-15 doesnt sound like it would fit into either cycle to me. Nitrogen is important to keep during both cycles but I would rather keep it way down during flower, if you take it out all together your leaves will yellow faster. Hope this helped someone
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