Broccoli Gongga Production Guide

General

In Zimbabwe the best growing climate for growing Broccoli is during the cool weather conditions of winter. During the hot, wet conditions of summer the head sizes tend to be smaller.

Site Selection

Broccoli grows very well in medium-to-medium heavy clay loam with good water holding capacity. It can be grown however in more sandier soils but will require more frequent irrigations and higher fertilizer rates. PH levels should be from 5.8 – 6.5 as Broccoli likes to have an alkaline soil. If ploughing, plough to a depth of 30 – 35cm which will make sure the soil is prepared for good root development, but make sure any old plough pan is broken up. If ripping then discing is preferred, this is also a good way of preparing a tilth. The soil should not be too cloddy, also not to fine. During winter months plant if possible on North facing slopes to achieve better soil warmth.

Spacing

If planting on beds which are at 1.5m centre to centre the in row should be 30cm apart and two rows placed on the bed 50 – 60cm apart. This should give approximately 44,000 plants per hectare.

Fertilizer

Broccoli can be susceptible to hollow stem problems caused by a Boron deficiency. If there is a Boron deficiency in the soil apply Solubor as a foliar spray every 2 weeks at a rate of 10grams/1 litre water. A balanced Basal type fertilizer of High C should be applied before planting. Fertilizer rates of 500kg – 750kg per hectare can be applied. Broccoli requires around 400kg per hectare of Ammonium Nitrate split into 3 applications from 3 weeks up to 6 weeks after transplanting. If the crop is being planted on sandier soils and also during the rainy season extra top dressings might be required after heavy leaching rains. Plantings going into mid-winter should be top dressed with Calcium Nitrate, instead of A.N. as it works quicker in cool soils.

Seedlings

Planting with seedlings is the most practical method. Plant the speedlings as soon as possible after pulling to avoid the tiny hair roots from drying out. Plant the plugs/speedlings into pre irrigated soils in which the field has been brought up to field capacity. After transplanting a light settling in irrigation is required to remove tiny air pockets between the plug and the soil.

Irrigation

Regular water applications during the dry winter months is essential. Overhead irrigation or centre pivot irrigation is the most common followed by flood and more recently drip irrigation which is becoming more affordable. Broccoli like cauliflower, the irrigations must be spot on or “Hollow stem” will occur due to fluctuations of water levels in the soil. Approximately 600mm – 750mm of irrigation should be allowed for to produce a quality Broccoli crop. Therefore planning water usage from Dams, rivers and boreholes can be worked out to match hectares to be planted. As the plant increases in size and leaf area, and the head starts to form, the amount of water required also increases. Irrigation should be planned on a weekly basis and the soil depletion area checked regularly to plan for the next irrigation cycle. The use of an evaporation pan should help with scheduling.

Rotations

In rotation planning do not follow with Broccoli if the previous crop has been a Brassica type i.e. Cabbage, Cauliflower or Rape. Always rotate with a legume or root crop.

Pests

Diseases

Weeds

Chemical Reference