Winter’s first hard freezes are arriving just in time for
Thanksgiving. You can help most herbs survive the winter by
taking the time to give them a 2- to 3-inch layer of mulch.

Many perennial herbs are winter-hardy in all or parts of Georgia
and can be left in the garden. A few plants are marginally
winter-hardy. They can survive a mild winter but may die during
a
severe winter unless brought indoors.

Winter Mulch Helps

Organic mulch such as pine straw, hardwood bark or bark-sawdust
mixture, is adequate winter protection for herbs such as mint,
chives and fennel. It protects them to minus 20 degrees
Fahrenheit.

A winter mulch helps maintain uniform soil temperatures around
the root system. It provides protection against the heaving
caused by frequent freezing and thawing of the soil in colder
areas of Georgia.

Some herbs require a thicker layer of mulch to protect their
roots during extended freezing weather. Don’t mulch heavily
before cold weather, since it will keep the soil warmer and may
actually decrease winter hardiness.

Mulch After Hard Freeze

After the first hard freeze, apply a 3- to 6-inch layer of
organic material such as straw, pine needles or chopped leaves.
Remove most of the mulch in the spring as new growth begins.

Rosemary, lemon verbena and a few other perennial herbs are not
reliably winter-hardy in areas north of Atlanta. So provide
extra
winter protection.

Cut plants back to within a couple inches of the ground after
the
first hard frost. Cover the remaining stub with soil. Then cover
the soil with 4 to 5 inches of mulch.

For lemon verbena, using a microfoam ground cover (the packing
material used around fragile items) works well, too. This
material can be held down with soil and will enable survival in
most years.

Alternatives

An alternative is to encircle the plant with a cage of hardware
cloth or chicken wire. The cage diameter should be about 12
inches larger than the plant (6 inches on each side). Fill the
cage with mulch.

Harsh, drying winds can prove as fatal as cold temperatures to
some of the less cold-tolerant herbs. Windbreaks can aid the
survival and appearance of herbs such as French tarragon,
germander, English lavender, Roman chamomile and winter
savory.

Covering with a few evergreen boughs will prevent the drying out
of silver and lemon thyme foliage. The more cold-sensitive herbs
have a better chance of survival if grown in a protected
place.

Other things that influence winter hardiness include
fertilizing,
pruning, watering and soil drainage.

• Fertilizing. Don’t fertilize herbs after early
  August.
  Late summer nitrogen applications will promote new growth that
  may not have time to mature before frost. The herbs will remain
  actively growing instead of becoming acclimated for cold
  weather.




• Pruning. Avoid severe pruning in late fall, since
  winter hardiness is reduced until the cuts have healed. Don’t
  severely prune woody plants within four to six weeks of the
  first
  severe freeze. In north Georgia, make the last severe cutting on
  sage, lavender or oregano before early September. Light pruning
  after frost is acceptable.




• Watering. Keep plants adequately watered during late
  summer and fall. Drought-stressed plants are weaker and often
  less cold-hardy. Water during a dry winter, especially before a
  severe freeze.




• Soil Drainage. Excessively wet soil or sites with
  standing water can decrease the winter hardiness of some plants.
  This is especially true for Mediterranean plants such as
  rosemary, thyme, lavender and French tarragon, which are adapted
  to dry climates. Provide adequate drainage by incorporating pine
  bark mulch or planting in raised beds.

After a severe winter, some outdoor plants such as rue, sage,
thyme and southernwood may appear brown and dead. Scrape the
bark
of a few stems to determine the extent of damage. If the stem is
green, delay pruning until after new growth begins.