This hydroponic technique simply involves replacing the nutrient solution with plain water, and is particularly recommended for fruit crops. Flushing prior to harvesting will remove excess nutrients from within the plant. This will improve the taste, smell and texture of the fruit produced.

In the last week of the plants fruiting period it goes through a final swelling up process. During this time it will stop taking up large amounts of nutrients and will even start to get rid of nutrient elements back in to the nutrient solution. By replacing the nutrient solution with plain water at this very last stage, water absorption and nutrient removal will be encouraged. If a plant is not flushed the fruit produced can have a bitter taste because of the nutrients still left within the plant.

Crops that require processing (such as herbs, which are dried), will also benefit from flushing as reducing the nutrients left in the crop will help in the drying out process.

Flushing can also be beneficial if a nutrient problem has been experienced. Flushing the plant for 24 hours and then putting a fresh nutrient solution into the system will help the plant rid itself of unwanted nutrients.

Flushing solutions can be purchased. These are usually organic formulations containing hormones which assist the removal of nutrients from the plant by encouraging it to draw up more water.

24 HOUR FLUSH

• Remove nutrient solution from the reservoir and clean out the system as much as possible.

• Pour plain water through the system (to flush through unwanted salts etc) and remove.

• Fill reservoir full of plain water/flush solution.

• Test and correct the pH level.

• Leave to circulate for 24 hours.

• Remove plain water/flush solution from reservoir.

• Replace with fresh nutrient solution.

FLUSHING PRIOR TO HARVEST

• In the final week/two weeks slowly reduce the nutrient strength (conductivity level).

• Three to five days before harvest remove the nutrient solution from the reservoir.

• Replace with plain water/nutrient solution.

• Test and correct the pH level.

• Leave to circulate until harvest.

If you have a conductivity meter keep testing the conductivity level of the plain water/flush solution in the reservoir. You will notice that the conductivity level will rise as the plant returns nutrients back into the water.

In some very hard water areas better results may be achieved if you allow the plant to develop to full maturity and then flush for a full week. The water in the reservoir may have to be replaced (with fresh plain water/flush solution) several times in that period.