I just found your question here because I was looking for the advice already given in cases like the one described. I have four autoflowering plants growing in coco/perlite, they're on their 3rd week of flowering, and I've noticed that even though there's yet no sign of deficiencies suggesting they are root bound (the plants still look healthy) but the roots can be seen on the coco surface (when water splaehes at watering them, though I do it gently, it removes some of the coco at the surface aqnd thus the roots can be seen as a tangled mas on the surface). Also there are roots sneaking thru the drainage holes of the 11 liter plastic pots I've got them planted in. I suspected a problem after I obseved that the coco was drying too quickly and I needed to be constantly watering the substrate with about 1-1,5 L of fsolution per pot every one or two days (letting about 20% solution run-off each watering). During vegetative stage I used to feed them "heavily" once a week (following the Flower Power feeding schedule for soil) and every two days I watered with pH'd water only (ocassionaly I added Ca/Mg/Fe and Clean Drip to the water). Into theflowering stage I'm feeding them at 1/4 dose every watering time (every two days). I am worried for this issue to decrease further the poor yields I could have with autoflowering plants. Besides letting the plant finish their cycle, I calculate I have still three or four more weeks to go, do you have further advice or recommendations?
I have to say that in a first instance I don't think of transplanting at this stage for the few weeks more they have left. Best regards.