I have been growing Dragon Fruit now for three years, this area is frost prone, and the temperature has dropped to 3 degrees some mornings. The Red variety of Dragon fruit is less tollerant to frost than the White variety.
As a result, the first year, all the Red plants were frosted to grount level and some of the White lost some young tips. To try to prevent this, I sprayed with liquid seaweed during the winter months; I sprayed the plants at the recomended rate each fortnight. At the end of the second winter I had lost about a third of the Red plants to ground level, and the rest had been affected to a lesser degree. None of the White was touched.
As a last effort to be sucessful with growing the Red Dragon fruit, I got some Silica & Potash Liquid Concentrate from Garry and, during the winter months, I mixed liquid seaweed and Silica & Potash at the following rates:-
Liquid Seaweed - 5 Litres
Silica & Potash - 500 mls
Water - 5000 Gallons
I sprayed all the Dragon fruit plants with this mixture weekly, and at the end of the third winter, these are the results:-
White Plants - None Effected
Red Plants - About 30 plants from 500 had some tips frozen; these tips were the new growth that appeared during the late autumn, the rest of the Red plants themselves were not effected by the frosts. We had several mornings with temperatures down to 3 or 4 degrees.
These results are a complete sucess, in comparison to those I received from the first winter. As a bye line, I watered all our fruit trees and vegetable garden with the same water, and, as a result, none of these plants were affected by frost. We picked tomatoes and capsicums all through winter.