Maximum Yield Australia/New Zealand 2020 September/October | Page 47

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Like most fruiting crops,
dragon fruit requires higher ratios
of nitrogen in the vegetative stages
of growth and increased potassium
when in fruit.”
Fragrant dragon fruit blossoms last only a single night.
Water and Nutrient Requirements
Like most fruiting crops, dragon fruit requires higher ratios
of nitrogen in the vegetative stages of growth and increased
potassium when in fruit. Since a number of relatively large
fruit are produced in a short time frame on each plant under
optimal growing conditions, sufficient potassium needs to
be supplied to maintain fruit yields and quality. Pitaya do
not require the same high EC that may be applied to crops
such as tomatoes to maintain fruit quality. EC levels
in the range of 1.0 for young plants up to 1.4
(with a pH of 5.8–6.0) are suitable for longterm
production. EC levels should be
measured in the drainage or leachate
solution draining from each growing
container to ensure EC is not climbing
during warm growing condition as
plants are sensitive to salinity damage.
Under optimal temperatures, mature
plants can use as much as three to five
litres of water per day or as little as
2.2 litres under cool growing conditions.
This process involves physically removing the anthers
from one flower and touching them to the stigma of another
flower at the time of opening. Alternatively, the pollen can be
collected using a small brush and used to pollinate several
different flowers. Once pollination has been successfully
completed, fruit development is rapid and harvest typically
occurs 28 to 30 days after the flower closes. Once fruit have
fully expanded and have a good level of skin colouration,
harvesting can occur. However, leaving the fruit on the plant
for an additional 10 to 15 days has been shown to improve brix
(sugar levels) in many cultivars. Brix levels for dragon fruit
are usually between 12 to 13 percent but can be as high as
20 percent in the red-fleshed varieties. Once harvested, fruit
can be stored for up four weeks at temperatures of 6-10°C with
a relative humidity of 90 to 95 percent to prevent desiccation.
Dragon fruit are a fascinating and attractive plant with
fragrant night blooming flowers and exotic fruit. They are also
a crop with good potential for the well-controlled irrigation
and nutrition that hydroponic methods can provide. Through
use of artificial lighting, day-length extension, and careful
selection of growing substrates, pitaya are likely to become
a popular greenhouse and indoor garden specimen.
Flowering, Pollination, and Fruit Set
Under indoor or greenhouse cultivation, dragon
fruit can be manipulated to increase the length of
the flowering and fruiting period. Being a long-day
plant, control over flowering with use of artificial lighting
is possible and can increase yields and productivity
significantly. While day length can be extended with the use
of lighting, it is also possible to induce flowering by using a
night break by providing a low level of light between 11 p.m.
and 2 a.m., similar to commercial cultivation in Taiwan.
Pitaya are night bloomers and fragrant flowers are only
viable for one to two nights with petals opening in the
evening and wilting by daybreak. In their native environment,
moths and bats pollinate the flowers, however, many
commercially available cultivars are now self compatible and
do not require cross pollination. Hand pollination, however,
can help give higher levels of fruit set and greater fruit weight.
Maximum Yield
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