First Grow: Having some deficiency issues (Northern Lights)

Hey guys.

Working on my first grow! Northern Lights from Sensi Seeds! Have 3 plants going in total, but having some big issues with one of them!

The plants are 32 days old, and have been in flower since about day 25. One of them is REALLY tiny, this is due to me snapping the stem while trying to LST DUUUUUUUUH that was not smart! but shes going strong never the less! The second plant is rocking bigtime, everythings looks real good! The third, and biggest plant, is the lady thats causing me all the problems!

The issue started a few days after entering the flower period and has continued since.

A little info about the grow

Running under a Mars Hydra 300 (135watt)
Using a soil mix of 50% potting soil, 25% perlite, and 25% Vermiculite.
At first I watered using only regular water WITHOUT PH'ing, after noticing the deficiency i brought a cheap PH meter and started PH'ing, i also brought Biothrive bloom nuts and started adding that at around 6.5PH.
The plant has now had 2x feeds and still is showing issues, it's slowling moving higher and higher up the plant.
Bud growth has really slowed, but its still seems to be stretching like crazy!

I've done some research and i think it looks like a Phosphorus issue. Due to the fact it started just after early fllower and i have the pink stems to!

What do you guys think ? is it Phosphorus ? will it be enough just using biothrive bloom or should i maybe add a PK booster to?

Thanks in advance for any help

Pictures below.

Looks like a cal-mag issue. I see both calcium and magnesium def.

Looks like a phosphorous deficiency to me, a little cal-mag won't hurt either though if you aren't supplementing with that already.

macsnaxWell-Known Member

Looks like a cal-mag issue. I see both calcium and magnesium def.

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KerovanWell-Known Member

Looks like a phosphorous deficiency to me, a little cal-mag won't hurt either though if you aren't supplementing with that already.

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The only Nutrients i'm using at the moment is the biothrive Bloom from General Organics, was debating picking up there Big Bud PK booster aswell though.
Sounds like it would be a good idea to get some Cal-mag to!

Exactly, looks rather like a phosporus defiency, but be very gentle with the pk boost, rather up your bloom nutes, than blasting the rootzone with too much of the good stuff. Be gentle and slightly up your dose of bloom feed, would only PK-boost in week 5-6 of bloom, otherwise it's rather a waste and might do your plant more wrong than good. Try to lower your ph a bit more, till around 6.3, but ofc that's a little to your preference.

Exactly, looks rather like a phosporus defiency, but be very gentle with the pk boost, rather up your bloom nutes, than blasting the rootzone with too much of the good stuff. Be gentle and slightly up your dose of bloom feed, would only PK-boost in week 5-6 of bloom, otherwise it's rather a waste and might do your plant more wrong than good. Try to lower your ph a bit more, till around 6.3, but ofc that's a little to your preference.

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Thanks for the advice! I'll try lowering the PH til 6.3 for the next few feeds.

Anyone that has any more advice regarding nutrients and the deficiency I’m seeing, feel free to chime in

Also any growing advice in general is welcome!

A very nice place to expand your growing-knowledge is 'grow weed easy' , you'll find there a small plantproblem diagnostic center of some sort. Where many common deficiencies and pests are discussed.