ok, I know you experienced guys are gonna go "duh". but thought I would share an observation with other new guys.We are dirt poor (pun intended). this last grow, didn't have money for new bags of soil mix. so reused the soil from last grow, (afterr shifting out roots, of course). didn't have enough to do all the large pots, so a couple of plants wound up in one gallon pots. they of course became root bound. well I broke down and bought a bag of soil, and repotted them in larger pots. they were almost half the size of the other girls. but wihin only about a week, they caught up! damn! I know being rootbound was poart of it. but it really feels like they were eating up that new soil. from now on, will be useing fresh soil for each grow, and use the old stuff for other plants that are getting put in the ground anyway
Yup absolutly soil should be changed after a plant has fully grown in it. During its life it sucks out all the natural nutrients and also the soil can become salt bound and contaminated in other ways as well.