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University
of Rhode Island GreenShare Factsheets
Root
Crops
Beets, carrots, parsnips, radishes, turnips and rutabagas
are all commonly known as root crops. These vegetables offer
a prolonged harvest season and, for the most part, a long storage
life. They also produce a large amount of food in a small amount
of space.
Root crops require a soil pH between 6.0 and 6.5. Have
your soil tested by the Cooperative Extension service (see
our GreenShare Factsheet on soil testing for
more information) and follow the recommendations given. Strongly
acid soils should be limed according to test results. Lime
(if needed) is most effective when mixed thoroughly into the
soil in the fall.
In addition to organic matter and lime, broadcast 1-1/2
pounds of 10-10-10 fertilizer per 100 square feet just prior
to planting your seeds.
It is also a good idea to sidedress the plants with the
same amount of fertilizer when the plants have reached about
one-third their growth. To prevent burning the roots, however,
apply the fertilizer three to four inches away from plants.
Root Crops grow best in well-drained, loose soil. Drainage
is important because these crops are among the earliest planted
and the latest harvested. If the soil is have (clay) you might
want to build a raised bed four to five inches high and 12
to 24 inches wide. Raised beds will help to reduce soil compaction,
permit easier digging and will allow carrots and parsnips to
attain greater length and be smoother in shape. Add sand and
organic matter, such as manure, to heavy soils to improve drainage.
The following steps may be used to prepare soil prior
to planting in the spring:
- Apply two to three bushels of well-rotted manure or
compost per 100 square feet. (If carrots are to be grown,
apply the organic matter in the fall prior to planting in
the spring.)
- Apply recommended amounts of lime.
- Rototill everything into the soil
- Broadcast recommended amounts of fertilizer just prior
to planting seeds and work into the soil.
Note: Using organic matter or manure that is not well-composed as a fertilizer
for carrots can cause the roots to become rough and branched.
Natural fertilizers can be very effective
when the right choice is made from the many types available.
See our GreenShare
Factsheet on Fertilizing Vegetable
Garden Soils for more detailed information.
Root crops will not do well in a dry seedbed. The seedbed
must be kept moist during the germination period. Therefore,
you may need to sprinkle the bed with water every day until
seeds have germinated. Some gardeners place a clear plastic
sheet over the row after the seeds have been planted and watered.
This warms the soil and conserves moisture. The sheet should
be removed as soon as seedlings emerge. This procedure is especially
useful for root crops such as carrots and parsnips which have
a long germination period.
Shallow cultivation (one to two inches deep) when weeds
are small is best. Pull weeds when they are small, because
as they get larger they compete with root crops for water and
mineral nutrition.
Once seedlings are up, a mulch material such as compost
or straw can be used to suppress weeds and conserve moisture.
Only mulch a moist, warm soil.
Some major insect pests include root
maggots on turnip, rutabaga and radish, leafminers on beets
and carrot rust flies on carrots and parsnips.
Root crops should not be put in storage until late fall.
These crops withstand autumn frosts and are better off in the
garden until nights are cold enough to permit proper storage
temperatures. Dig root crops when the soil is dry and prepare
them for storage. Cut the plant tops about 1/2 inch above the
crown and do not wash until needed.
Root crops keep best between 32 and 40 degrees F. They
require high humidity to keep from shriveling.
Turnips and rutabagas give off odors; do not store them
in your basement or home cellar. You may store them with other
root crops in an outdoor cellar or pit. All other root crops
can be stored in your home cellar if it is cool enough. Root
crops keep their crispness longer when bedded in layers of
moist sand, peat or sphagnum moss.
Beets (Beta vulgaris):
- See GreenShare Factsheet on Beets for
detailed information
Carrots (Daucus carota):
- See GreenShare Factsheet on Carrots for
detailed information
Parsnips (Pastinaca sativa):
- Varieties: Hollow Crown, Model, All America
- Seeding: Sow parsnip seeds 1/2-inch deep at
a rate of 1/2-ounce per 100 feet of row. Since parsnips are
slow to germinate (approximately two weeks), quick germinating
radish seeds can be sown along with the parsnips. The radishes
will mark the rows and permit earlier cultivation. Note:
if your garden soil is heavy, cover the seeds with sand,
vermiculite or fine peat rather than soil.
As soon as plants reach a height of two to three inches, they should be thinned
to stand two to three inches apart. Since parsnips require a long growing
season, there is only one seeding which should be made as early in the spring
as the ground can be worked.
- Harvesting: More than almost any other vegetable,
parsnips are improved by cold or even freezing. The roots
can be left in the ground until late fall or on through the
winter. I f left over winter, they should be covered with
a mulch to prevent alternate freezing and thawing and deterioration
of the root. They should also be harvested early in the spring
before new growth starts.
Radishes (Raphaus sativas):
- Varieties:
Round--Cherry Belle (red), Comet (red), Scarlet
Prince (red), Sparkler (red/white), Giant White Globe (white),
Round Black Spanish (black)
Oval--Early Scarlet Globe (red), Cavalier (red)
Turnip-Shaped – Scarlet Turnip White-Tipped (red/white)
Oblong--French Breakfast (red/white), Chinese rose Winter (red)
- Seeding: Sow seeds 1/3-inch deep at a rate of
one-ounce per 60 feet of row. Radishes will germinate in
four to five days. Thin seedlings shortly after emergence
to avoid disturbing the root system of radish plants left
in the garden. For a continuous supply, make plantings every
10 days during the early spring and again starting in August.
Radishes grown during midsummer produce woody and pithy roots.
- Harvesting: Radishes can be harvested at any
stage.
Turnips (Brassica rapa):
- Varieties: Purple Top White Globe (white-fleshed),
Snowball (white-fleshed), Aberdeen (yellow-fleshed)
For greens: Shogoin, Seven Top
- Seeding: Sow seeds 1/2-inch deep in rows 15-inches
apart at a rate of 1/2-ounce per 100 feet of row. After the
plants become established, thin plants three to five inches
apart. Plant turnips in early spring, then again in summer
for a fall crop. In hot weather, the roots are often strong
or bitter in flavor and become pithy when they reach maximum
size.
- Harvesting: Turnips reach a good size and are
ready to harvest in 60 to 80 days.
Rutabagas (Brassica campestris var. napobrassica):
- Varieties: American Purple Top Laurentian
- Seeding: Plant rutabaga seeds from mid-June
until July for fall harvest. Sow seeds 1/2-inch deep in rows
24-inches apart at a rate of 1/2-ounce per 100 feet of row.
Thin seedlings to a spacing of six to eight inches.
- Harvesting: The roots should be allowed to reach
full maturity before they are pulled, usually in late September
and October, in order to be sweet and of peak quality. They
do not become pithy if overmature as turnips do.
Adapted from the University of Massachusetts Cooperative Extension Service,
2001
Pesticides
are poisonous! Read and follow all safety precautions on labels.
Handle carefully and store in original containers out of reach
of children, pets or livestock. Dispose of empty containers
immediately, in a safe manner and place. Pesticides should never
be stored with foods or in areas where people eat.
When trade names are used for identification, no product endorsement
is implied, nor is discrimination intended against similar materials.
Be sure that the pesticide you intend to use is registered for
the state of use.
The user of this information assumes all risk for personal injury
or property damage.
For more
information, call the URI CE Gardening and Food Safety Hotline
at 1-800-448-1011 or (401)874-2929 from outside Rhode Island;
Monday-Thursday between 9 am and 2 pm.
University
of Rhode Island Cooperative Extension provides equal program
opportunities.
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