Nutrition

There will be sufficient nutrients in the bag to feed the plants for the initial few weeks after planting, after which liquid feeding will be required.

The feeding can be given by using the proprietary feeds or made up from straight fertilisers.

During spring growth nitrogen and phosphate demand by the plant is high which maximises shoot, root and flower development.

As growth continues potassium demand increases reaching a peak as harvesting commences.

Following harvest there is a period of regeneration, the plants require nitrogen and phosphate to sustain crown production and also initiate flowers for the next year.

Feeding therefore needs to reflect these different stages. From establishment to the start of flowering a feed giving approximately 120 mg/litre nitrogen, 50 mg/litre phosphate and 150 mg/litre potash should be given. During flowering the potassium content should be increased to 250-300 mg/litre.

For the January crop this is the only feeding required. For the autumn crop extra nitrogen and phosphate should be given during September. Extra feeding is likely to be necessary in February/March for the overwintered crop as nutrient levels in the bag at that time are generally very low.

Proprietary feeds which give nutrients in the correct proportions can be used ie 1:1:2 for early growth followed by 1:1:3 during flowering and 2:1:4 or 3:1:6 during the autumn.

The conductivity of the feed should be monitored regularly After planting conductivity should be 800 us/cm increasing to 1200 us/cm pre-flowering, and to 1500-1700 us/cm between flowering and fruiting. These figures should be added to water supply conductivity.

Periodic nutrient analysis of the feed run-off is recommended.

Leaf tissue samples are a useful means of checking nutritional levels in the plant.