When to start fertilizing my plants!

They are very small for 4 weeks old plants. Something seems wrong with your soil. If they weren't getting enough light, they would be stretching but that's not the case. So I thinks it's a feeding, ph or soil issue. Or you are just unlucky with these two seeds and they won't grow well. Small plants like these shouldn't be fed though. Usually you start feeding a plant when it reaches around 10cm in height or has 2-4 real leaf pairs. So I wouldn't feed them anything in this stage but root-juice or similar products. I've noticed in you other diary, that you germinate them fully in some way and then put them into the medium. Autoflowers don't like that. Try putting them directly into the soil and letting them germinate naturally. Hope that helped and good luck on your grow! 😘

Your plants should be a lot bigger than that and looking at your watering habits, you need to water until you get runoff and then let it dry back enough before watering again. If your soil is dry then your roots will not like it and die, stunting root growth - that is your plants foundation. I would water with ph adjusted water to start with and then go low and slow with the nutrients.

4 weeks? ... gonna harves 8 grams out of that plant. Probably doesn't need much fertilizer because it isn't growing much -- window sill light isn't enough. Your cotys are starting to pale, so i guess you could provide some 1/4 or 1/2 dose fertilization, but if you do, i'd hold off for a week or two to see how it reacts... that tiny plant isn't exhausting all the nutrients from your pot in 4 weeks, that's for sure.. it'd be bigger if it did. you need to get at least 25ish DLI to produce decent nugs. Even that will be larfy, i bet. Ambient co2 has a rough ceiling of 35-40 dLI for reference. You can look up your regions DLI per month - maps exist to reference. You could guesstimate what X hours on your window sill exposed to sun would provide.. then much less the rest of the day and guesstimate how much DLI it gets on your window sill... if it's well short of 25DLI, the results won't change. do a guerrila grow or buy a grow light...

depends on the soil 4 weeks ? ffs 😂

They should be bigger then this by 4 weeks. Something went wrong here. Might want to check your mediums composition and work back from there.

I have used Terra pro alpad of times in the past it's 1 of the best in my eyes. There is some feed within but it's only a light mix so I would definitely give a feed ASAP I wouldn't go mad and fill the whole pot till it's running out, she's still small I would do ring around the base and work outwards the next time this encourages root stretch enticing the roots to search otherwise you could end up with overly wet soil and for to long causing root rot so be cautious of that until the roots are established and then go to a full pot feed.. Grow on and good luck growmie

Yeah bro, at 4 weeks you can definitely start feeding but go super light like ¼ of the recommended dose first time. Watch how they respond for a few days, then slowly increase. Autos can be sensitive early on, so gentle is the key