Is repotting necessary if the pot is huge and I use a fertilizer?

Question

I am new to gardening and I am using an app to help me take care of my plants. For each plant, there is an instruction/recommendation on when to repot it. It seems that in most cases it is every year.

I am wondering if this is really necessary if I use fertilizer and my plants are in big enough pots for their species. Will they thrive without repotting?

I am not sure if the following details are relevant, since I am looking for a general answer. But just in case, they are outdoor plants. The one I am most interested in is a basil plant in a 24x53cm pot.

Answer 1

there is an instruction/recommendation on when to repot it. It seems that in most cases it is every year

I can't even phantom that statement. Repotting destroys some roots(the better you do it the fewer but still). It stresses the plant because of the new conditions of moisture, airing, type of soil, temperature. It involves work.

The root system of plants is often underestimated in size - I've read in some cases it may become as deep as the plant*. But basil in large pots - nah.

If You are applying liquid fertilizer in proper amounts AND are using proper sized pots I would advise only airing. Take a fork and disturb the top layer of the soil, trying to destroy as few roots as possible. If any yellowing or curving unnaturally leaves begin being observed do ask a separate question.

_{* - Lucerne doesn't get higher than say half a meter but is said to be able to produce 10m deep central root. But this is an exception, in my limited experience plants have roots about two thirds of their height at most}

Answer 2

In 40+ years of growing houseplants, I could probably count on two hands the number of times I've potted any of them up (put into a larger pot). I usually pot them down or put them in the same pot (sterilized) or a smaller pot. This may come from working with bonsai. Also, I really don't have that much room so I need the plants to be smaller and more compact.

Every year or so I pull the plant out of the pot and check the roots. Only if it's root bound will I repot. I rake the roots out with a fork and clear most of the old soil away. I cut off the largest roots leaving most of the feeder roots. Those are trimmed enough to fit back in the pot.

I trim the top of the plant in about the same proportion as the amount of root I pruned. If I cut 50% of the root, I prune 50% of the top. Then the plant gets put back in the same pot or a smaller one.

Protect the plant for a week or so to let it recover from its shock. New growth should come soon after.

I've never tried this with herbs like basil so YMMV.