Hi Emilya.You appear to be severely overwatering these plants by watering too often. I will bet that when you think they are totally dry, you are checking the top instead of worrying about stale stagnant water sitting in the bottom of the container. Use the lift the pot method to see if it is time to water. If you can sense ANY water weight in the container AT ALL, by lifting the container, it is NOT time to water yet. Your lower leaves are showing the classic symptoms of having the lower roots shut down because they have not seen oxygen in some time.
Establish a strong and aggressive wet/dry cycle in these containers, and after 3 wet/dry cycles, this problem will go away.
Ok that makes sense to me thanks.great job on the watering techniques then... and lets just move past that then knowing that this isn't the problem. The pH definitely is a big problem though...
First, the range in soil is 6.2-6.8, and soil is designed to have a positive drift to it. When you water at 6.8 you are already at the top end of the usable range and any nutes that are best mobile at the lower portion of this range are likely locked out. To make matters worse, the buffers in the soil immediately try to drift the pH upwards and so your fluids quickly move totally out of range shortly after you water.
The better strategy is to come in at 6.3 pH, where mathematically the most nutrients are the most mobile. Then let the soil drift the pH upwards through the entire usable range, picking up all of the nutrients in turn.
You could be right there, I suppose it's their job to get us to spend more.A lot of grow shop guys have no idea what they are doing, and some actively give bad advice to soil growers so that they give up and go to a hydro based method and spend lots of money in the shop. Be very careful when getting your advice.
From the biobizz website and instructions on how to use their feeding chart, in bold letters I noticed the following:
Remember to keep an eye on the pH in your water to make sure that your plants can absorb every last drop of the nutrients you give them.
Hi EmilyaI am surprised that your response to the plants not getting enough nutrients is to continue to give them half strength of the recommended nutes at this stage of development. Feed them... and over 2 or 3 watering cycles the plants will catch up... but you can't solve a deficit by continuing to go light on the nutes.
The new soil will help too... just give them time to repair themselves.