Maximum Yield Australia/New Zealand March/April 2019 | Page 44

Left: Manual pollination of citrus flowers is required in an indoor garden;
paint brushes can be used to distribute pollen. Top: Citrus often set many
more fruitlets than can be carried to maturity. Bottom: Lemons are well
suited to container or hydroponic production.
“A light level similar to that provided for fruiting tomato
and capsicum plants is ideal, provided citrus trees are not
overcrowded and kept pruned for maximum light interception.”
Tips for Indoor Cultivation
Apart from good light and sufficient warmth, citrus benefit
from some gentle air flow through the foliage. This helps
remove any stale air and excess humidity and reduces the
disease risk to the plants. One of the most vital aspects of
growing fruiting citrus indoors is pollination which is essen-
tial for fruit set. Outdoors, bees and other insects carry out the
pollen transfer role with great efficiency, however, indoors this
needs to be done manually. The process is relatively simple
as citrus don’t need to be cross pollinated. A small paint brush
can be used to collect the yellow pollen grains from within a
citrus flower; these are then brushed off into the stigma (found
at the top of the long column in the middle of the flower). The
stigma becomes sticky when receptive to pollen, allowing the
brushed-on pollen grains to adhere and stay in place.
This process can be carried out a few times a week when
citrus trees are in flower and is usually highly successful. It is
normal for many types of citrus to produce masses of highly
fragrant flowers, far more than the tree could ever support as
fruit. For this reason, it’s not usual to see the excess flowers
or tiny fruitlets drop from the tree — this is just a natural
self-pruning process which thins fruit to only those which the
tree can support through to maturity. Young trees may only be
able to carry a small handful of fruit in the first season and
fruit loading will increase with the age and size of the tree.
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Maximum Yield
Harvesting Hydroponic Citrus
Harvesting citrus fruit is relatively simple — it’s best to cut
these from the tree rather then pull them off as this often
snaps branches or causes fruit damage. Lemons and limes,
once mature, can be left on the tree for a considerable
length of time, often months, before harvest and this is
often used as a way to store excess fruit until it’s required.
However, retaining a high fruit load can delay flowering
and the next crop of young fruit, so prompt removal is often
a better option. Excess citrus fruit and even k-lime leaves
can be stored in the freezer until required or processed into
juice, jellies, marmalade, or syrups.
Whether it’s the new and exotic Australian finger lime or
a common everyday lemon tree, hydroponic citrus fruits
are a valuable addition to any indoor garden. Fragrant
flowers, glossy deep green foliage, and bright decorative
fruit make these ideal productive specimens well suited
to hydroponic systems.