Winter Storage of Tender Perennials

Tender perennials are an integral part of many home landscapes in the Midwest. Most have a
long blooming period and put on excellent displays
of color until it freezes in the fall. The biggest
problem with tender perennials is that they will not
survive Iowa's harsh winter weather if left outdoors.
The following tender perennials should be dug in the
fall and stored indoors until spring graces our
doorstep once again.

Tuberous begonias (Begonia
xtuberhybrida) come in a wide assortment of colors and types.
Some of the flower forms include camellia,
cascade, carnation, picotee, and non-stop series.
Container-grown plants can be brought indoors for
winter enjoyment. Those tubers left outside should be
dug after a killing frost. To properly condition the
tubers for storage, place them in a warm, dry location
for approximately two weeks. Then bury the tubers in
a box or sack filled with sphagnum moss or vermiculite. Store them in a cool, dry location.

Caladium (Caladium xhortulanum) is a
great plant in the shade! The caladium is grown for
its colorful foliage rather than its flowers. When
the foliage dies back in the fall, carefully lift the
tubers out of the soil and find a warm, dry place to
cure them. Typically the process is complete in
two weeks. Store the tubers in dry sand, vermiculite,
or sphagnum moss in a cool, (50 degrees F),
frost-free area.

Gladiolus (Gladiolus hybrids) is stunning in
the garden and in arrangements, but they need to be
dug and tucked away for the winter months. The
gladiolus or glad develops from a growing
structure called a corm. A corm is a short, thickened
underground stem where food is stored. When the
foliage has yellowed, lift the corms carefully, cut off
the foliage 1 to 2 inches above the corm and allow drying for a week in a sunny location. Corms can
be treated with a fungicide to prevent disease while
in storage. Remove and discard the remains of the
old mother corm located at the bottom of the
large, healthy corm. Place the corms in old onion sacks
or nylon stockings. Then store the corms in a cool,
dry, frost-free location until spring planting occurs.

Though calla lilies (Zandedeschia spp.)
are tropical in appearance, they can be
successfully grown in the Midwest. After the foliage has
been damaged by a frost, cut off the tops about 2
inches above the soil line. Dry the calla rhizomes in
a warm, dry location for one or two weeks. Bury
the rhizomes in vermiculite, sawdust, or peat moss,
and store in a cool (45 to 55 degrees F), frost-free area.

The large, banana-like foliage of the canna
(Canna xgeneralis) stands out in the garden.
Some can get to be about six feet in height, while
others top the two to three-foot range. After a killing
frost, cut the stems back to about 3-4 inches above
the soil. Carefully dig up the rhizomes, let them dry
for a few hours, and then place them in crates or
mesh bags. Store at 35 to 45 degrees F.

Dahlias (Dahlia hybrids) stand out like
beacons in the summer garden. With more than
40,000 varieties to choose from, it's difficult to not like
at least one. After a killing frost has destroyed
the foliage, the top of the dahlia should be cut away,
and the tubers should be carefully dug and labeled
with the variety name. Wash the tubers with water
to remove as much soil as possible. This lessens
the chance for soil insects to destroy the tubers while
in storage. Dry the tubers in a site protected
from strong winds and out of direct sunlight. When
the tubers become dry to the touch, remove any
portion of the stalk that remains and place the tubers
upside down in vermiculite to ensure that any water in
the remaining crown tissue drains out.

Although all of these plants require more work to keep than your average perennial, their
attractive flowers and foliage are well worth the extra effort.

This article originally appeared in the September 15, 2000 issue, p. 113.

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