Carrots
Carrots – Dancus carota sativus
Umbelliferae Family
Carrots are a cool season crop best grown in temperatures between
60-65F. If planted early they will produce a spring crop before
temperatures get warm enough to reduce the flavor. In Las Cruces
we can get two plantings a year, with roots from the late summer
planting holding “in ground” well into winter.
Timing
Recommended planting time for spring Carrots is Jan 15 –
March 1. For fall and winter growing, August is recommended for
planting. Timing in spring is critical because carrots loose flavor
when soil temperatures exceed 65-70°F - mulch carrots heavily
in late spring to reduce soil temperatures. When planting in August,
shading the soil surface will increase germination since carrot
seed will not germinate at temperatures above 95°F. Shade and/or
mulch will help keep the seed bed damp for the 2 weeks needed to
germinate seed.
Planting and Growing
If planting in rows, sow seed on ¼” spacing. Thin
to 2” apart when carrots are a two inches tall. If planting
on a grid in wide beds, plant in rows within the wide bed. Space
between bed rows should be at least 6-8 inches.
Sow seeds ¼ inch deep in loose soil that has been amended
with well-aged compost. Do not add manure or high nitrogen organic
fertilizers to the carrot bed - high nitrogen content cause excessive
top growth and hairy roots. Adding calcium and some high phosphorous
organic fertilizer (soft rock phosphate) to our soils is also advisable
to insure an adequate available supply. For calcium, adding gypsum
is the most cost effective option.
Carrot requires even watering with adequate soil water always available.
Avoid drought stress and soggy soils. Water frequently (daily if
needed) until germination is complete. The critical periods for
water are during stand development and root growth. Drought stress
during these times will cause roots to be course, cracked or have
an off taste. During the root growth period be sure to water to
a depth of at least 6 inches.
Improving Germination
Sowing radish seeds in the carrot row makes for good companion
planting. Radish seed will germinate in 3-4 days marking the rows,
breaking the soil crust and providing some shade as they leaf out.
Harvest the radishes as space is needed for carrot thinning.
Mixing carrot seed with sand before sowing is one way to get more
even seed spacing and reduce thinning later in the season. If you
cover the seeds with a potting mix instead of soil, you will increase
the germination rate by reducing crusting and increasing moisture
content in the seedbed.
In spring, harvest carrots 65-75 days after planting (depending
on variety) and before mid April. For summer/fall carrots, timing
the harvest is not as critical, since soil and air temperatures
are cooling down. In winter, carrots can be stored in the ground
and harvested as needed.
Problems
Hairy Roots – excess nitrogen in the soil
Forked Roots – compacted or cloddy soils
Split Roots – uneven watering
Tough Roots and Low Sugar – high soil temperatures (above
70F)
Diseases – few here and generally not damaging
Insect Pests
Black Swallowtail Butterfly larvae will feed on the foliage
Root-knot nematodes are a serious problem for carrots
Wireworms (the larvae of Click Beetles) can damage roots, if abundant
Leafhoppers that transmit the carrot yellows disease can also be
problematic
History
Their ancestry dates back thousands of years to Afghanistan where
the wild ancestors are still found today. Original cultivation was
probably for seeds and foliage for medicinal use. They were grown
in ancient Rome and early Europe but not in the orange color form.
Breeders in the Netherlands developed orange colored carrots during
the 17th century.
You can still plant carrots in March, but it best to use short
season varieties this spring and wait until August to plant the
longer season and storage types.
Good Gardening and Good Eating,
Darrol Shillingburg
Doña Ana Extension Master Gardener
March 2011
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