Losing colors :'(

Thanks everyone for your feedback, I can't validate more than one answer, but yep, I will take your answers and give them more nutrients with my tea compost and more water too ! Many thanks

Organoman says everything

Hi your girls need some more water/nutrients. It's now you need to increase everything. Light, water and nutrients. Slow and steady. Because they are in preflower and stretch. Just keep an eye on them on how the react. 🤛

One moment please! 2 litres for 30 L pot for the whole week? Did I read that properly? If so, this yellowing can be caused by underwatering. They need much more water to thrive. I’d say at least 1 liter per day for one plant. Just keep runoff at minimum 10%, preferably more.

Plant still needs a well balanced diet in early flower. They get super hungry for the stretch. If they don't get what they need they will take it from the leaves. Those bottom leaves will also fade because of lack of light. I would clean her up at the bottom so the plant can focus more up top.

spesso nella parte bassa non arriva una buona luce quindi la pianta tende a lasciare indietro le foglie piu nascoste che non riescono a fare la fotosintesi come si deve la parte sopra mi sembra di un bel verde intenso un po' di azoto ci sta ma nella norma come consigliato

I wouldn't say this is an expert opinion but yes leaves losing colour means that your plant is trying to save up on nutrients because it doesn't have enough to go around for everyone. Your plant has started the flowering stage so increasing nutrients and watering is very important because they are most thirsty + hungry at this stage. Most nutrient instructions double the amount of nutrients from the veg stage to the bloom/flowering stage, so I suggest you do the same. Don't worry, it will recover in no time :) Happy Growing.

Because the lower older leaves are the ones showing the deficiency and by the looks I would definitely go with nitrogen for sure. Hope this helps.