first time grow

Hey welcome from the uk also. You will not want to add nutes for another 10-14 days yet, or it will hurt the young plant. You can get a generic bottle of tomato feed for flowering stage but will want something to help you through vegetave stage, before the days of the Internet I used to use babybio (little green bottle in most garden/hardware shops including wilko etc). That will do if on a tight budget. Or you can go online with plenty of choice. 👍🌱

Are the values on your diary right? 600w led and 25cm away from the plants? They are really stretchy and in my experience if you have 24 hours of light they won't stretch too much past the first cotiledon/leaves. But they're looking all right so they will explode very soon, they're starting to show the first set of fan leaves, those will help capturing more light and from this week on you will see exponential grow. Keep taking good care of them! Looking forward to see your diary next weeks!

Hey growmie... A Magnesium deficiency can cause reddish purple stems. A good cannabis-friendly nutrient system has a significant amount of magnesium, but if you're using very soft water, or RO water, you may need to add a Cal-Mag to your nutrient regimen. Temperature – Heat or especially cold can trigger red stems in some places also. Sometimes it can even be genetics. Hopefully this was helpful and remember Happy Growing and Free your mind one puff at a time.