Climate requirements of carrots
Carrots is a cold weather crop. The ideal growing season is from early autumn to late spring. Carrots can be grown throughout the year if summers are not too hot like the lowveld in South Africa. Although heavy frost damage leaves, it does not affect the root, so the carrot itself stays marketable. Expect longer sow to harvest periods during winter than in summer. Leaving the crop for too long in the field before spring, can cause the plant to bolt. Select the right variety for each season by continuously testing new varieties.
The colour, form and quality of the carrot is influenced by temperature and soil moisture. A good effective irrigation system is essential for carrot farming. Dry spots in a field will result in lower total yield. Carrots take on average 3-3½ months to mature. A grower can expect more cracked and forked carrots during summer but they can be used for processing or dicing.
The ideal average temperature for carrots is between 15°C and 20°C. Night temperatures should be as close to 15°C as possible and day temperatures about 20°C. New carrot varieties can tolerate more extreme temperatures but they are expensive, but they increase the growing season. Poor colour will develop if day temperatures are below 15°C and above 30°C.
Soil requirements for good carrot growth
Soil moisture affects the colour and shape of carrots. Dry soils cause long thin carrots while too wet soils yield light coloured fat short carrots. The surface of grade A carrots are smooth with little hair or side roots. Growing carrots in high temperatures combined with wet and dry spells, causes a rough appearance which reduces marketability. If you have to grow carrots during summer test as many heat tolerant varieties you can and make sure you have a good irrigation system to cool them of during the hottest time of the day. Good quality carrots have a thin core or xylem. Expect thicker cores during summer with slightly more bitter taste.
The best carrots are grown in a loose, well drained sandy loam or loamy soil. This does not mean that carrots cannot be grown in turf soils. It all comes down to soil preparation and irrigation. pH should be between 6.0 and 6.7, which is ideal. Avoid soils with high organic content which will cause excessive side shoots and leaf growth. Organic material causes rough or coarse carrots which reduces their marketability. Avoid soils with pH lower than 5 which will reduce quality significantly. Brack soils are also a problem so management and variety must be tip-top. Growing carrots in brack soils is more of an art than basic farming.
Soil Preparation for carrots
Carrot seed are small and are sown directly into the soil. Soil preparation is extremely important to obtain a good even stand. Uneven soils with clods will result in uneven growth and high variation in carrot size. Use a light roller to even out the seedbed before planting. The soil must be damp enough to ensure proper and even germination. Sprinkler and pivot irrigation provide the highest yields. Although flood irrigation is cheap, it cannot achieve the same yields as sprinkler irrigation. Control eelworm with fumigation in infected soils.
Some diseases of carrots are transmitted in the soil. An effective rotational cropping system is therefore of great importance in eliminating disease problems. Carrots fit particularly well into a rotational cropping system with cabbage, cauliflower, lettuce, beans, peas and tomatoes. Allow enough time for any compost or kraal manure to decompose before planting carrots.
Don’t plant carrots more than once every 3-4 years on the same land.
We all know that an accurate fertilizer recommendation is not possible with a soil analysis but every growing wants to know what the average recommendation is. In general, apply 900-1100 kg 2:3:4(24) composite fertilizer before planting time. After 8 weeks apply 100-200 kg/ha LAN as top dressing. Do not apply any compost or kraal manure as it causes crooked and hairy carrots.
Carrots are sensitive to boron deficiency but that is mostly in very sandy soils. Apply 10-20 kg/ha Borax powder before planting on B deficient soils. Although carrots are tolerant to high B levels, the next crop may not be, so be careful when adding Borax to the soil.
Carrots remove 4kg N, 0.6kg P and 4.6kg K per ton produced. A more detailed fertilizer program can be viewed in the article Carrot Fertilizer Application Tables According to Soil Types.
Carrots are sensitive to Boron deficiency. Apply 10-20 kg/ha commercial Borax powder before the season starts. Carrots are very tolerant to high B concentrations in the soil.
Sowing time table for carrots in South Africa
In some areas carrots can be planted throughout the year. Low germination is the result of high temperatures during early season due to damping off. As a general rule the following time table can be followed in South Africa:
(Heavy frost in winter and cool summers)
|Gauteng, Mpumalanga, North West and Free State||Late August to mid March|
(Light frost in winter)
|Gauteng, Northern Province, North West, Mpumalanga and Kwazulu Natal||August to mid-April|
|Lowveld- South||Northern Province, Mpumalanga and Kwazulu Natal||February to April; July to August|
|Lowveld – North
(Very hot summers and frost free winters)
|Northern Province, Mpumalanga and Kwazulu Natal||March to early August|
|Free State and Northern Cape||All||August-October; End January-March|
|Kwazulu Natal||Midlands and coastal regions||July-April|
(Winter rainfall area)
|All||August – end March.
High rainfall areas before end February
Carrots are sensitive to soil born and transferred diseases. A proper crop rotation system is essential to prevent significant losses. Ideal rotation crops are peas, beans, cabbage, cauliflower, lettuce and tomatoes. Make sure the organic material used in the previous crop is decomposed before sowing carrots. Remember too much organic material cause hairy roots and a bitter taste.