Growing conditions
Climate
Cabbage is a cool season crop. The optimum temperature range for cabbage production is 15 to 20°C. Above 25°C growth stops. The minimum temperature is 0°C (freezing), but cold hardened plants can tolerate temperatures as low as -10°C. Young plants less than six millimeters in diameter can tolerate both colder and warmer temperatures than older plants. These young plants are said to be in the juvenile phase of growth. Plants which have matured past the juvenile phase will flower if temperatures are less than 10°C for five to six weeks. This is a response to temperature, and daylength is not involved.
Poor environmental conditions during growth can lead to quality problems when the cabbage is harvested. High temperatures and low moisture can cause small plants which give low yield. These conditions can also lead to long stems in the head and can cause the outer leaves to drop. Cold temperature during growth can also lead to long stems in the heads and bolting, or flower stalk formation.
Soil, Nutrition, and Irrigation
Cabbage can be grown on a wide range of soils, but the crop is sensitive to soil acidity. The optimum pH is six to 6.5, and at pH's greater than seven the disease club root can be present. Cabbage is a heavy user of nitrogen and potassium and requires frequent side-dressing. Cabbage is considered a hard crop on the land, and many growers will rotate to other crops that do not have such high fertility requirements. Cabbage is grown on mineral, sand and muck soils.
On sandy soil where there is a high water table, cabbage is irrigated by sub-surface irrigation. On deeper sands it is a perfect crop for drip irrigation since fertigation can be used. In many new fields where cabbage is grown on sandy soil, plastic mulch is being used to prevent wind damage from blowing sand particles. This will increase the use of drip irrigation. Regardless of the method used, cabbage requires about one inch of water per week. The supply of water should be even throughout the growing season to prevent cracking of the heads.
Establishing the Crop
In Florida 90 percent of the cabbage crop is transplanted. In the Fall four-to-five-week-old plants are used, while in the Winter six-to-eight-week-old plants are used. Recent research showed that transplant age and the size of the transplant cell are critical factors in determining cabbage tolerance of pre-emergence herbicides.
Many cabbage transplants are grown outdoors in open beds. Nationwide, and in all crops, there has been a trend to direct seeding, rather than transplanting. The benefits of direct seeding are:
- avoids intensive labor needed to raise transplants
- growers often have trouble obtaining high quality transplants due to disease problems
- supply often is a problem when grower wants to put transplants in the field.
The drawbacks of direct seeding are:
- stands are often uneven and plants are not at same stage of maturity
- labor is needed for thinning
- the cost of hybrid seed
When growing cabbage transplants outdoors in Florida, the biggest production problem is black rot. This is a disease caused by the bacterium Xanthomonas campestris, and is also called black spot or black leg. It attacks all cole crops and good sanitation of the transplant operation is essential to produce disease free plants. These practices include:
- use clean flats
- do not move contaminated soil
- use disease free seed
- buy certified transplants
- fumigate or rotate transplants beds
- destroy diseased plants and crop residue after harvest
- irrigate from a well, not an open ditch
- eliminate cruciferous weeds
- do not mow plants to harden
- do not wet plants
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