GardenBanter.co.uk - View Single Post

13-03-2005, 10:26 PM

wrote:
We just moved to Mid-Michigan from Northern California. Just about
the
only thing we miss about our old house was the ability to grow herbs
year-round, particularly rosemary. We would like to find a way to
keep
rosemary bushes alive through the winters here (zone 5b). I've read
that it is sometimes possible with the hardiest varieties in
sheltered
areas.

We just replaced the original furnace in our 50 year old house and as
part of the installation, a new exhaust pipe was routed to our
foundation in the backyard. The result is a lot of warm, steamy air
comes out of the house near the ground in a particularly sunny spot.
I'm wondering how I could take advantage of this situation for the
rosemary. One idea I had was to make some sort of cold frame near
the
vent to capture the heat without shocking the plants too much. Any
suggestions?

give it a try, but don't be shocked if it fails. suppose you have 30
people in the house while the temperature outside is near 0F. The
furnace won't kick in very often and the rosemary will freeze to death.
same if you heat with a wood stove. the coldframe alone will give you
1.5 extra zones but you probably need three. a double layer coldframe
may just do the trick but if strong winds knock it down, even once?
That is all it takes.

My Michigan rosemary is in a 12 inches pot that comes in in october and
goes out in april. Rosemary will take frost, which is why it goes out
so early, and is undemanding as a potted plant (needs watering half the
time compared to a regular houseplant for example, and little
fertilization). That plant grows strongly (it is a very thick 2 feet
bush) and gives us plenty rosemary. We also have large outdoor
perennial patches of mint, sage, lemon balm, thyme, and oregano, all of
which grow easily here, and I dry pounds of leaves in july and
september. thyme, sage and oregano last well into december, so don't
get discouraged.