On 3/22/12 10:11 AM, maryrose wrote:
i have a large rosemary bush over 4ft high 4ft wide any tips on pruning?

Rosemary and its relatives such as lavender and sage need to be pruned
carefully.

If you live in a climate where frosts occur regularly in the winter, do
not prune after mid-October (northern hemisphere); wait until spring
when no more frosts are expected. Pruning promotes new growth, which is
especially tender and would be damaged by frosts. While I do get some
frost in the winter, it is only occasional and not severe. Thus, I can
prune my rosemary at any time of the year.

When you make a cut, you must either remove the entire branch or else
leave some live foliage below the cut. "Live foliage" includes foliage
on side branches below the cut. If you cut into bare wood with no live
foliage remaining, the branch will die back to its base. All this
requires hand shears, lopping shears, and a small pruning saw so that
you can select each branch and make individual cuts. Do not use hedge
shears, which cut many branches at once. Too often, hedge shears will
leave several branches that have no live foliage; you would then see
significant die-back.

I prune my rosemary to clean out lower growth and expose the branches,
which can be quite picturesque. The plant is about 30 years old. Its
branches are twisted and gnarled. At the base, it is about 6 inches in
diameter.

If you really want to reduce the size of the plant, however, I suggest
that you do it gradually. After you lightly trim, wait. The plant
should get new shoots lower down. Then you can trim above those new
shoots.

--
David E. Ross
Climate: California Mediterranean, see
http://www.rossde.com/garden/climate.html
Gardening diary at http://www.rossde.com/garden/diary