When And How To Trim And Care For A Root Bound Rosemary Plant

Question From: Salem, Missouri, United States
Q: I have a root bound Rosemary plant in a very large pot. I can't transplant into a larger pot and really don't want to plant outside right now. It is too cold outside. So I have read about root trimming for root bound plants and wondered. Could I cut back the branches, trim the roots, add fertilizer(we have not been using any) and put it back into the pot? Would the plant survive? Would that allow me to keep it in the the pot for another 4 months?

A: Your techniques are correct, however, the timing is not. Your best bet is to keep the plant going until March or April and then do this extreme potting procedure. It needs cool temperatures, as much light as you can give it and humidity. A large pebble tray filled with water would be helpful. Do not allow the soil to dry out as a dry rosemary is a dead rosemary. When you repot use an organic fertilizer such as fish emulsion. Best And Happy Yardening, Nancy

Comment: With rosemary being from the Mediterranean area, I understood that it actually needs for the soil to dry out for about 4 days to a week before watering. Overwatering is death to this plant. so now I don't know what to go with. We discovered that this rosemary plant is almost completely roots (only roots) in the pot and little to no soil. we didn't know this when we brought it into the house. We know winter isn't the normal time to do major plant work, but I think it will die in this pot if I don't do something soon. I had been regularly watering it every other day, and I'm sure it got too much water despite the way it is able to drain off the extra. Half or more of its leaves have turned brown/ black and fallen off. The room it was in, is cooler (60 - 65)than most of our house in the winter. It can stand temps down to 40's but does best outside. I have put it outside as often as I can when the temps are in 50's or higher, then back inside. I have a window that it s beside and a grow light was added about 3 weeks ago after one session of loosing lots of leaves/ pine needles, So I'm curious about where you got the information you sent about moisture for rosemary. Our primary question had been: should we also trim the branches of the plant when we re-pot it soon into some soil? The re-potting needs to happen now, not in 3 or 4 months. I highly doubt it can last that long.

Response: You can remove the dead material. I have been growing Rosemary indoors for years and I water when the surface of the soil has dried a bit, but the rest of the soil in the pot is still moist. While it struggles a bit from lack of sun it's alive and well with all its needles. I have visited herb farms in the south of France and discussed culture with the growers. The soil is cold and damp in France and parts of the Mediterranean in winter where Rosemary thrives. A good book you might invest in is The Big Book of Herbs by Art Tucker and Tom Debaggio. Good Luck with your repotting project. Best And Happy Yardening, Nancy