Whilst attempting to get a close up shot of your plants, your flash was too close has created a bleaching affect in your photo.
You can diffuse the flash by putting a piece of masking tape/ decorators paper tape over your flash, if the flash is till to strong in you photographs try adding another piece on top of the first one.
Once the light from you flash is diffused you will get a more natural rendering of light on your plant and a truer sense of colour.
This will make identifying any deficiencies you might have a lot easier, if you have a tripod it will make the picture clearer without movement blur.
Low to no nutrients soil , so yes, it would seem now is about time to start feeding them with a Grow nutrient, did you remember to PH correct your nutrient before feeding?
I don't know how you measured your nutrient but a syringe is a good way to accurately measure small quantities of nutrients to avoid over feeding.
No problem adding a little molasses which happens to contain some Magnesium, the question remains, did you PH correct your nutrients after adding them to your water.
6.5 PH is ideal for soil but once you have added the nutrients and molasses the PH will no longer be at 6.5 PH, which is why it is important to correct it.
Another thing you could do is make sure you PH meter is properly calibrated, do you do this?
Calibrating PH meters is not hard but you will need calibration solutions and distilled water and some clean beakers. You tube has some great videos.
An EC meter is a very handy device to have if you are using Chemical based nutrients, If using organic nutrients follow directions on the bottle as you won't get a correct reading from an EC pen with Organic feed.
Cal/mag deficiencies often show up in week 3 - 4 so adding some at this stage is no bad thing, if you are growing under LED your cal/mag up take will be higher. Again folow the instructions on your cal-mag bottle or let me know if you are using Epsome salts and I'll give you the details on how to use it.
Be sure to let your soil dry out some before watering again, cannabis likes a wet/dry cycle.{just thought I would mention it}
"Nuts burn", I instantly realized what you meant buy this, but there are many {I include myself} who have a warped sense of humor and can't help finding "Nuts Burn" a humorous tile
.... what are the N-P-K numbers on that fert'? With a very mild soil, it's time to start ramping up your nute strength gradually; And, do you have a dedicated Ca-Mg supp' yet? Molasses will do in a pinch, and as an occasional "treat" of sorts ( don't want to put too much sugar into the soil, too often),...but a proper supp' is best for general maintenance and treating defc.,...
