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Oct 9, 2009 05:38 PM

Herb dilemma

Getting pretty cold here quickly in the midwest (Michigan). I have three huge rosemary bushes and a fairly large bay leaf plant that I am going to repot tomorrow and bring in. My issue is why do my herbs die when it gets to about January?
Would I be better off keeping them in a cold garage to copy winter weather or what should I do to help them survive. I am tired of watching them die - depressing!

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  1. Plants being brought in for the winter need to be brought in before the weather becomes too cold, preferably before any heat is on inside. Otherwise, the thermal shock will set them back badly.

    I have handled rosemary and bay for years in Chicago without any problems. They are grown in pots year round. I move the pots to an enclosed porch in September and then into my sun room once the weather is cooling off more and reverse the process in the spring. These plants go semi-dormant in the winter. Do not repot or fertilize until February or March. Be careful not to over water but do not let them dry out too far. Light even moisture is the goal. You do not want to encourage foliage growth in the fall.

    Depending what part of Michigan you are in, a cold garage will be at least as cold as in Chicago and will be death on bay and rosemary due to temperature and lack of light. The natural habitat for these plants is a more Mediterranean climate where winters are nothing like Midwest winters.

    1. I'm in sw VA but I've used this method in PA & NY. My bay tree I've always brought into the house when night time temps started averaging 40-50 F and put it in the sunniest location. My potted herbs come into an unheated garage just before a hard frost is predicted. I've been lucky with garages or unheated rooms with southern exposure except for one house where I had to use lights on a timer. I give them a trim when I move them. Then I steadily decrease watering them as it gets colder until they go dormant (Usually around the end of December, beginning of January) at which point I water them lightly when the top inch is dry. Around March-April they begin showing signs of life (although some never go completely dormant) and I slowly increase watering them and then give them a light fertilizer when they have several sets of leaves. When the spring frosts are over, I divide and repot them or transplant into the ground and continue as usual.
      I also leave herbs (same ones I bring inside) to winter over in the garden with success. Not the bay of course, but rosemary has always made it for me wherever I've lived. In late fall after the herbs are done growing, I cut them back near to the ground and mulch heavily with straw held in place with sheets of plastic and lawn staples. This seems to give them the protection they need against freezing and heaving, the heaving seems to be what kills them. Then in spring after the last frost I pull the mulch off them and continue as usual.

      Upstate NY gets pretty cold but I don't know if it gets as cold as MI or Chicago. We have lakes but I don't think our lake effects are as severe as yours. So, YMMV.

      1. Update - Hard frost warning flashed across the screen last night during early evening news, so out I went. Picked my sage, dug up all my plants, rosemary, bay leaves and even my figs. Was out with a flash light for goodness' sake! Potted them all and decided to ease the shock, put them in my garage. Quite sunny today and so I put them out and brought them back in the garage.
        The hard frost never happened, but glad I got it all done. Now what? I should bring them in to a sunny location? South facing window with indirect sunlight? Should I give them some moisture with a squirt bottle?

        1 Reply
        1. re: itryalot

          Now that you've got them potted you can continue to leave them out as long as the weather permits. They'll need a little more attention to watering than if they were in the ground. Stick your finger in the pots and if the first inch is dry, give them a drink. To keep them producing inside put them in your sunniest window. If you want them to produce all winter long keep them in the house, lightly fertilize from time to time. You may have to supplement with a grow light if you want to keep the plants stocky. If you want them to go through an approximation of their normal cycle keep them in a very cool or unheated room (I use the garage, it has a south facing window) and allow them to go dormant. You'll still have to give them a little water through the winter. Your fig and especially the bay you'll want to keep in the house. Depending on your cultivar the fig may be hardy down to around 30-35 degrees. Hardy Chicago and Brown Turkey figs handle those temps pretty well. They will lose their leaves if kept in a cold place. If you have a bush type fig it's not unusual for them to die back to the ground and come back in the spring.

        2. I need some help with this too! Except my herbs are already in boxes, and I have no garage or indoor window to use (tiny apartment). This is what I have.

          Box one: Thyme, Rosemary, Chives and Tarragon.
          Box two: Basil (Genovese), Basil (Thai), Parsley and Sorrel. (Do I have to let this one go?)

          Also we have a pot with spearmint and pineapple mint.

          Does anyone know if we can keep any of this going with grow lights in our basement? What lights do I need to buy -- will just regular fluorescent lights work?

          Something like this?

          2 Replies
          1. re: SLOLindsay

            We use the Gro-Lux lights in the link for our seedlings but we also have our plants by windows. If you have no windows in your basement I would recommend going for the Agrosun tubes since they're full spectrum. Put the fixtures on chains so the lights are just a couple of inches above the plants. As the plants grow adjust the fixtures up the chains. If you keep your herbs trimmed you may not need to adjust. Also, a small fan on low helps with air flow around the plants, important if they're kind of crowded in. Regular fluorescent won't work well, they don't cover the light spectrum needed by plants.

            Your basils may just naturally run their course on you. Just pot up some more seeds and put them under the lights.

            1. re: morwen

              Thyme, chives, tarragon and mints can spend the winter outside. They are usually hardy perennials (some varieties of thyme might not be). Long ago an herb lady told me some plants need to go thru a winter dormancy.
              Parsley is a bienniel. It wants to set seed in its second year. I leave mine in the ground and continue to use during the second year. I kept cutting off the flower heads and was able to continue using it during the summer while my newly seeded plants got established. But, it did not put out many new leaves during the second summer. It was really at the end of its life cycle.

              There are different varieties of rosemary, I managed to happen on a fairly hardy one that could tolerate some dryness. The first two winters it spent in a north window on the back of our toilet. I think the extra humidity from the shower in our tiny bathroom helped it. The leaves are not as glossy as most rosemaries yet the flavor is the same. It spent last winter in a semi heated NH garage with some sun (garage doors face south and have windows in the top half) and managed to survive. I gave it away this fall after taking some clippings.

              Another NH gardener said she puts her potted chives in an unheated garage to go thru a dormancy. Then she brings them in so they can start re-growing. But, I don't remember what time of year she brought them in. Here in NH a lot of herbs will stay green until quite late in the year.