Carrots are relatively tolerant of a wide variety of temperatures but prefer cooler growing conditions. Carrots are hardy and can be planted as soon as the soil can be prepared.
Carrots require relatively large amounts of moisture and are not tolerant of drought. Prolonged hot weather in the later stages of development may not only retard carrot growth but may result in an undesirable strong flavor and coarseness in the roots. The ideal air temperature for carrots is between 6o°F-70°F.
Carrots thrive in deep well drained, sandy loam soils with a pH of 6.5 to 7.0. Generally, root crops do not grow well in acidic soils. Soil should be loose to a depth of 12″ or more to allow for good root development. Carrots grow downwards and therefore soil preparation is very important. Soils may be formed into a raised bed to obtain optimum drainage, maximum root length and smoothness, and to reduce soil compaction.
Do not add compost or manure to the carrot beds prior to planting unless it is very well decomposed, as too much nitrogen will encourage roughness and branching. Make sure soils are free of debris such as rocks and twigs. Smooth carrot beds before planting.
Carrots are compact vegetables and do not require much space. Carrots benefit from adequate space and when crowded are sure to grow deformed roots. Baby carrots may be provided with a tighter spacing of 0.75 to 2 inches. Thinning to a final spacing of 2 to 4 inches is necessary if carrots are intended to be grown to maturity.
Direct seeded carrots require a well-prepared seedbed with adequate moisture, carrot seeds may be sowed 0.25 to 0.5 inch deep, 0.75″ apart, within 2″ rows spaced16-24 inches apart. Sprinkle the soil with water but do not allow the soil to form a crust before the seedlings emerge. Thin carrots at about 3 weeks to a spacing of between 0.75 to 4 inches depending upon cultivar and root size desired.
Sow carrots as soon as the soil can be worked. Sow a fresh batch of carrots every 3 weeks to provide a continuous supply of fresh carrots. These seeds germinate best in soils around 85°F. Germination will take 6-18 days.
Carrots need an even moisture supply to become well established and to produce good root development. Carrots need at least 1″ of water from rainfall or irrigation each week during the growing season. Always soak the soil thoroughly when watering to also help promote good root development. Watering once a week is often sufficient on most soils. However, very sandy soils may require more frequent watering.
Pest and Disease Control
Diseases that affect carrots include Leaf Spot, Aster Yellow, Storage Rot and Root Knot.
Leaf Spots are caused by the fungi Cercospora carotae and Alternaria dauci and by the bacterium Xanthomanas carotae. Cercospora leaf spots are brown to gray and are more prevalent on young foliage than on old foliage. Alternaria leaf spots are generally dark brown to black and are more prevalent on older foliage than on young foliage. Xanthomonas leaf spots are similar to Alternaria leaf spots but the two cannot be distinguished without microscopic examination. Yellow margins may be present around spots caused by each organism.
The fungi and bacteria are seed- and soil-borne. Cercospora and spores are spread by wind. Xanthomonas cells and also the fungus spores are spread in splashing and running water, wind-blown soil, and on implements. Cercospora and Alternaria can infect leaves only when they are wet. Xanthamonas can infect leaves when the relative humidity is high (90 to 100%) for a 2- to 3-day period.
Carrots infected with Root Knot may have forked roots and irregular round galls and spindle-shaped enlargements on the tap and side roots. These symptoms are caused by the same kind of root knot nematode (microscopic worm) that causes root galling on tomatoes, cucurbits, lettuce, and other vegetable crops. Several species of the root knot nematode (Meloidogyne spp.) may be involved.
Aster Yellow disease on carrots is caused by a mycoplasma, is characterized by production of yellowish dwarfed leaves, usually arranged in a tight rosette. Older leaves may develop reddish margins. The root at the crown bulges up into a cone and hair-like roots develop on the taproot. The mycoplasma is spread by leafhoppers.
Carrots Storage Rots are caused by fungi and bacteria. Soil moisture conditions and mechanical injury affect incidence of rot. More rot develop in stored carrots from poorly drained than from well-drained soil. Carrots mechanically injured during harvest and during preparation for storage were more likely to develop rot. High relative humidity, a requirement for long-term storage, do not result in excessive rot in carrots cooled promptly after harvest.
Carrot Rust flies are 1/5 inch flies in size, slender, shiny, metallic blue-black with lighter head, legs, and wings. The larvae or maggots are white and legless, and are often found in the root of the host plant. This pest has been widely reported as a pest from muckland areas where carrots and celery are grown, but has not generally been a serious problem in carrots grown in the mineral soils in upland areas. This pest attacks several host plants including carrots, parsnips, celery, parsley, celeriac, fennel, dill, caraway, and coriander.
The larvae mine in the roots, causing holes that are subject to rot by secondary organisms. Heavy maggot feeding is indicated by drooping, discolored foliage.
Harvesting carrots early may help to avoid second-generation damage. Seeding may be delayed until after the first-generation flies have passed, and harvest may be done before second-generation flies appear. Other cultural controls include deep plowing, rotation of crops, and destruction of wild hosts (Queen Anne’s Lace, wild parsnips, etc.)
An insecticide may be applied as a drench in furrow at planting to control first-generation larvae. Do not apply an insecticide that will not be compatible with planned rotational crops.
Harvesting and Storage
Carrots are easy to harvest. Simply pull up the plant by the tops, the foliage. Carrots are usually harvested when the roots are 0.75″ to 1-1/2″ in diameter at the upper end, but can be harvested when the crops reach a usable size. For baby carrots, harvest the roots when they reach finger size and 4-5″ length.
Carrots destined for storage must be handled carefully during and after harvest to avoid bruising, cutting and breakage.
Carrots harvested and handled in hot weather are more likely to decay and require extra care to prevent wilting. Wash carrots if they are harvested under wet conditions and are to be stored. Many potential decay-causing organisms are removed by washing. Also, clean, washed carrots allow freer air circulation.
Prompt cooling to 40°F or below after harvest is essential for extended storage. Poorly pre-cooled roots decay more rapidly. Ideal storage for carrots is 32°F and 99% relative humidity.
Mature carrots are well adapted for storage and are stored in large quantities during the fall and winter. Mature topped carrots can be stored 7 to 9 months at 32°F-34°F with a very high relative humidity, 98%-ioo%.
Carrots should not be stored with vegetables and fruits that give off ethylene gas such as apples and pears. Some surface browning or oxidative discoloration often develops in stored carrots.
Return on Investment
Cash overhead costs in growing carrots include land rent, property taxes, insurance, employee wages, and office expenses. Operation cash costs include equipment and its maintenance, labor, seeds, fertilizers and pesticides.
Carrots may be marketed fresh or processed. Profitability may differ on how portions of the crop are marketed.
The highest profit from carrots may be obtained from a harvest in June.
Where to get seedlings:
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Author: Carmela Abaygay, Marid Digest, photo from www.freedigitalphotos.net