Root_cellars_Vegetable_Storage.pdf

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Vegetable Storage
in Root Cellars
by
Michele Hébert
Extension Faculty, Agriculture & Horticulture
In Alaska, cold winter temperatures and cold
soils all year long, make root cellars a good
method for storing vegetables. Root cellars offer
gardeners a method for storing produce through
the winter or for holding produce until there is
time for canning and freezing. Consumers can
also use root cellars to store produce bought in
bulk from the farmers market or grocery. High
quality, locally-grown vegetables can be avail-
able from the root cellar throughout the winter.
Stored fruits and vegetables are living organisms
and to keep the quality and nutritional value
high, certain storage conditions should be
met. The best conditions for each crop
will vary, but the important require-
ments include temperature, moisture,
and ventilation. To have the best
success using cold storage,
select late-maturing varieties
of vegetables that have
been allowed to grow
late into the fall and
fully mature.
Temperature
During the day, plants make food
through photosynthesis. At night or during
storage, plants respire or use the stored food to
survive and keep alive. To keep produce at the
highest quality, it is important to slow down the
growth and respiration with cool temperatures.
Respiration reduces quality and speeds up with
warmer temperatures. The optimum storage
temperature for most vegetables is between 32°
and 40°F. This temperature can be maintained
by a combination of utilizing insulation on walls
HGA-00331
and ceilings, thermostats, and a heat source when
needed. An adequate heat source can sometimes
be a little as a 100 watt light bulb placed near the
floor. Keep in mind that heat rises and warmer
temperature will be found at the top of the root
cellar. Thermometers can be positioned through-
out the cellar to monitor temperatures.
Humidity
High humidity (between 80 to 95 percent relative
humidity) keeps vegetables from drying out. The
exception to this rule is with cucubits (squash
family) and onions—vegetables
that produce a thick wall. These
vegetables prefer dry stor-
age conditions and tend to
mold when the moisture
is high.
The easiest way to keep the
moisture high is to have a
dirt floor which helps the root
cellar keep a constant moisture
during the winter. If the floor is
concrete or wood it may be neces-
sary to place several pans of water on the
floor. Vegetables are 90% water. The fuller the
root cellar the higher the humidity. That is why
a small, full root cellar will work better than a
larger one.
Ventilation
Ventilation is used to help control the tempera-
ture and humidity. Excess moisture that encour-
ages mold, can be exhausted and the room aired
out when not in use. Be sure the ventilation
system is screened to keep rodents out.
Figure 1. Example blueprint for below floor root cellar.
Harvest and storage
Choose to grow vegetable varieties that are
late maturing or have good storing qualities.
Harvest as late in the season as possible before
a killing or damaging frost. Vegetables should
be harvested in the morning after the dew has
time to dry but before the afternoon heats up the
vegetables. Remove the field heat by cooling in
a cold place.
Produce can be grouped according to storage
requirements into four groups; cold and very
moist, cold and moist, cool and dry, and warm
and dry.
Most vegetables need a cold and very moist
storage condition because of thin skin or leaves.
Thin-skin produce including
beets, kohlrabi,
turnips, carrots, parsnips, radishes, and
cucumbers
are harvested leaving a
1
/
2
inch stem
and stored to retain moisture. This can be done
with packing material or perforated plastic bags.
Layer vegetables in packing materials such as
moist sawdust, sand, and peat moss.
Leafy vegetables such as
celery, Chinese cab-
bage, endive, kale, and cauliflower
should be
lifted out of the garden with roots attached and
replanted in moist packing material. Vegetables
with strong odors such as
cabbage and turnips
are best when individually wrapped in newspaper
to prevent drying out and reducing smells.
Potatoes
and
tomatoes
need a cold, moist stor-
age condition. Potatoes need to be cured in a
warm environment before cold storage. Harvest
potatoes late in the season and store in the dark
at a warm temperature for 7 to 10 days to allow
the potato to dry and develop a thick skin. Then
potatoes should be moved to a cold, dark area.
If potatoes are stored in crates or boxes together
they will share moisture and keep each other
from shriveling. Do not store potatoes above
40°F or they will begin to sprout.
Tomatoes are harvested leaving a short stem
attached. Place tomatoes one layer deep in a
shallow box and cover with newspaper to keep
them from drying out.
Onions,
like potatoes are cured for several
weeks after harvest. This allows the skin to
become papery and roots to shrivel. Onions are
best stored in a cool dry location with good air
circulation. Onions are often braided or put in a
mesh bag and hung from the ceiling of the root
cellar.
Winter squash and pumpkins
are best stored
in a dry warm spot such as the corner of a room
indoors. Cut as late as possible before a frost,
leaving a 2 inch long stem. The more mature, the
thicker the skin and more resistant to decay and
drying out the vegetables will be. If stored in a
moist location, squash will quickly mold.
Building a root cellar
A root cellar should be cold, dark, and damp and
be in a convenient location. It is easier to con-
trol temperature and humidity in a small cellar.
Most families can get by with an area 4 x 6 feet
in size. The most convenient locations may be
a walled off part of a basement or garage area
containing a window for ventilation. A com-
mon location in rural Alaska is in the floor of the
kitchen. With an inside installation be sure to put
a vapor barrier towards the inside of the root cel-
lar protecting the rest of the house from excess
moisture and rot.
In both attached and separate structures select
wood designed for direct burial for the walls
and floor. Check with supplier to be sure that the
wood treatment is not toxic in this application.
Uninsulated masonry walls will conduct the cool
ground temperature into your root cellar and are
very durable. Water drainage is important for
keeping out surface water in the spring and dur-
ing summer rains. Insulate above-ground walls
to protect from cold temperatures in winter and
warm temperatures in summer. Be aware that sea-
sonal frost can extend over 4 feet deep seasonally
into the soil. Keep this in mind being sure to have
the insulation extend below the frost line.
Figure 2. A well-insulated room in the basement can provide good, cool, moist storage for vegetables.
Storage Time and Temperature for Some
Vegetables Grown in Alaska
Vegetables
Temp F.
% Humidity
Storage Time
Comments
Beets
Brussels Sprouts
Cabbage
Carrots
Cauliflower
Celery
Chinese cabbage
Cucumbers
Kohlrabi
Onions
Parsnip
Potatoes
Squash
Tomatoes
Turnips
Small Fruits
32°
32°
38°
32°
32°
32°
32°
50°
38°
32°
32°
38°
60°
60°
38°
32°
90-95
90-95
90-95
90-95
85-90
90-95
90-95
85-90
90-95
55-60
90-95
85-90
55-60
55-60
90-95
85-90
3 Months
4 Weeks
4 Months
5 Months
3 Weeks
4 Months
2 Months
3 Weeks
3 Months
8 Months
6 Months
8 Months
3 Months
8 Weeks
3 Months
7 Days
Leave 1” stem.
Wrap to avoid drying
Late maturing varieties **
Top leaving
1
/
4
” stem *
Wrap in leaves *
Dig with roots ***
Dig with roots ***
Waxed or moist packing *
Trim leaves *
Dry for two weeks.
Top leaving
1
/
4
” stem *
Pack in boxes unwashed.
Winter types, leave 2” stem
Single layer in covered boxes
Waxed or moist packing *
*
Pack in moistened sawdust or sand.
** Wrap in clean newspaper.
*** Replant in moist sand.
This publication replaces Storing Vegetables in Root Cellars and Basements in Alaska, written in April 1982 by Ray
Morgan, Extension Community Development Agent. This major revision was written by Michele Hébert, Extension
Land Resources Agent, Tanana District in March 1999.
Visit the Cooperative Extension Service website at
www.uaf.edu/ces
1-877-520-5211
356/4-82/ORM-MH/1000
Reprinted September 2008
America's Arctic University
The University of Alaska Fairbanks Cooperative Extension Service programs are available to all, without regard to race, color, age, sex,
creed, national origin, or disability and in accordance with all applicable federal laws. Provided in furtherance of Cooperative Extension
work, acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture, Peter Pinney, Interim Director, Cooperative
Extension Service, University of Alaska Fairbanks.
The University of Alaska Fairbanks is an affirmative action/equal opportunity employer and educational institution.

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