Royal queen seeds first grow

it oculd mean several things, but more infor and such needed. get any commonleaf symptom chart. start looking it over to compare what you see. takenote of how they progress as this will help you delineate between common leaf issues.. e.g. if it starts at top bottom or all over, etc can eliminate possibilities. p tox can cause tips to burn. k tox and deficiency can cause tips to burn, though the deficiency quickly will work along the margins (outer serated tips). both of those tox symptoms are as much about what they lock out as what the p or k causes. S tox and deficiency cause burnt tips. So.. more info needed. from what i see your ratios will be off with your nute lineup. if oyu get one or 2 of the npk in a good range, the other 1 or 2 will be off.

Nutriet/nitrogen toxicity from over feeding. Your plants are very green, indicating too much fertilizer in general. It is not a deficiency. Some clear, close up pictures showing the actual problem would have helped with providing more specific opinions.

If you are in early flowering it is a potassium deficiency.

defoiliation is kinda oldschool technic, to be sure that the plant gets enough Light. nowadays under quatum boards there is no big necessity to dothat, just taking away some disturbing leaves in flower is enoug just tremember, you are slowing down the plant, she tries to reproduce the mu´issing leaves. so just moderate picking in flower every few days is totally enough