Canna Winter Storage :
I copied this with the permission of the Author;
Mr. Kent Kelly (from the Garden Web Canna Forum)
Canna rhizome winter storage has many possibilities but one must understand
that some cultivars (varieties) store much easier than others.
Most cultivars will survive winter storage if the following is kept in mind. Cold
and wet is not acceptable. Hot (warm) and dry is also very harmful.
Ideally cannas should not be lifted for storage until after a light killing frost or
even a moderate freeze. This allows the rhizomes to begin the normal semi-
dormant cycle. Cannas dug for prolonged storage during the warm (hot)
growing season are most susceptible to serious disease problems.
Canna rhizomes are unlike many flower bulbs that complete their life cycle after
producing a new ‘bulb’ which usually goes through a dormant cycle. The
rhizome that produced this year’s growing stalks will ultimately die and rot, but
new rhizome growth is continually produced from the old mature rhizome in the
growing season. Rhizomes will continue to maintain cellular activity based on
temperature.
As the temperature declines, the cellular activity is greatly reduced which
makes winter storage possible for many who must lift the rhizomes to prevent
freezing. The usually accepted storage temperature is between 45 F and 55 F
with a relative humidity of about 75% to 90%. It is necessary to prevent
‘excessive’ rhizome dehydration (water loss) and to keep the temperature low
enough to prevent or stimulate new growth.
Try not to bruise or injure the rhizome when digging. Injuries allow disease to
easily enter the tuber (rhizome). It is not necessary to remove the feeder roots
attached to the rhizome although the digging process will surely prune many
and none will be viable after extended storage. If it is necessary to divide the
rhizome for storage, it is much better to ‘break’ the tuber as opposed to cutting.
The break injury will seal and heal quickly if allowed to dry for a day.
Remember that the semi-dormant rhizome is a living organism needing limited
air exchange. Do not store in small sealed containers for extended time
periods. The ideal storage area would be the long forgotten "root-cellar". Lift
the clumps and store in the cellar - cover with a little mulch. It does not matter if
the soil is removed or washed away just so the temperature is slightly above
freezing and the rhizomes do not dry out or begin to grow.
Which of the two extremes is worse -- cold or warmth?
If one has to choose between the two, I suggest you choose the ‘cold’.
Remember that cannas in many zones are mulched and left in the ground.
Providing the soil is reasonably well drained and the mulch is heavy enough to
prevent freezing the canna tubers generally survive very well even if the soil
temperature approaches freezing for extended periods of time. Cold
temperatures allow certain bacterial diseases to infect the rhizomes to a
greater degree but the same is true for the higher temperature storage areas.
You are simply fighting a different bacterium.
If one has removed the soil from the canna clump, I would definitely prefer the
cold side of storage. If the soil is not removed from the clump or only partially
removed it will tolerate the warm area. It is important to remember when storing
canna tubers in the warmer areas to prevent excessive dehydration of the
tuber. This is why most individuals recommend using ‘slightly moist’ peat or
other filler agent when storing the tubers.
Leaving the canna clumps as large a possible is very beneficial. Divisions can
be made just prior to planting. If you must store in a slightly elevated
temperature area, you might want to choose the coolest part of that area and
place the tubers directly on the floor with a insulating cover over them.
If you have a large ‘pile’ of cannas for storage you need to be aware to the fact
that they will create heat within the center of the pile. Not a fire hazard, but you
often get a heat build-up and this will cause premature sprouting and growth.
You may need to check the ‘pile’ from time to time and rearrange the clumps.
Regards, Kent
