A new grower who need's a little help...Thank's...

[Lazarus]

The little ones in soil are the exact same age as her big sister on hydro... They are so small and ill, could be a ph problem, a deficiancy of mg/ca or what else... Would be thankful for any advice...

Feeding: a.n.-iguana juice grow, silica, a.n.-tarantula, calmag, mycorrhiza
Water: ph-6.3 ppm-550/700
Soil: plagron promix, canna seedcut
Light: phlizon PH S2 (200w) at a 85cm distance

The hydro plant is doing good so far...Just in case your'e interessted:

Drip feeding: T.A. tripart (micro,grow,bloom), calmag, trichoderma, hesi root complex
Water: ph-5.6 ppm: 740

The strain's are: "Blue cheese" from barney farm's
"THC flash" from seed 66

[3Berries]

Looks like the ProMix has no or little nutes but is mostly peat? I would guess the pH is way low in the lower 5s if you watered to runoff on the soil.

https://growdiaries.com/nutrients/plagron/promix

[DW2]

Howdy Lazarus, the hydroponic plant will always grow faster than a soil plant because the nutrients are already in a form more readily usable for the plant. That reduces the time (and effort for the plant) to develop and grow to maturity. My hydroponic grows have averaged around 20 t0 23 weeks from germination to harvest.
Good luck with your growing.