Fire & Spice - Growing Hydroponic Chiles
By Dr. Lynette Morgan, Maximum Yield Magazine
Hot chile peppers have become a popular hydroponic crop grown by both
hobbyist and commercial growers all over the world. Much of this
popularity has arisen from an increasing interest in spicy and strongly
flavored ethnic foods, combined with the fact that chiles are one of the
most colorful and rewarding crops to produce. While most people
recognise the fiery nature of chile peppers, many hydroponic growers of
these plants also discover the complex and fascinating flavor profiles
that different chile varieties can produce. Chile pepper fruit provide
not only heat of varying degrees, but also intensive color, flavor,
aroma and texture, making them one of the most versatile small plants
for hydroponic systems.
Chile Fire and Flavor
When eaten with certain foods, hot peppers have the effect of
stimulating saliva and causing the release of endorphins which creates a
sensation of pleasure. Chiles heighten the mouth's sensitivity and as a
result the taste buds perceive the food to be more flavorful than it
actually is, this is why chiles are often used to spice up otherwise
bland and starchy ingredients such as corn and beans. The 'heat'
experienced from eating chiles comes mainly from compounds called
'capsaicinoids', although other pungent compounds have recently been
identified in hot capsicum fruit. The sweet bell peppers contain very
little of these heat producing compounds, although they are similar in
regards to their production requirements. Capsaicinoids are extremely
concentrated and powerful compounds, and even a drop of a solution of 1
part to a million imparts a fiery kick to the taste buds. Of the five
major capsaicioids that have been isolated from chile fruit, each has
its own characterized 'bite' sensation in the mouth. Some capsaicinoids
produce a numbing effect, some burn in the back of the mouth, some on
the centre of the tongue, some burn the lips rather than the tongue and
others are extremely painful at first but then leave behind a warm
sensation.
Capsaicinoids have no flavor or odor - the ability to sense it depends
entirely on the physiological action of the compound (i.e. burning) on
the tongue. The pungency or heat factors are caused by the stimulation
of pain receptors in the mouth. For this reason, human taste panels were
used in 1912 to develop the 'Scoville Organoleptic test' which is still
used today to measure the heat of pepper fruit (expressed in Scoville
heat units). Sweet bell peppers have zero Scoville heat units, the
Anaheim peppers have 1000, while the Jalapeno and Cayenne can range in
heat from 2500 to 25 000 heat units.
The pungency of the fruit of any chile plant is influenced greatly by
the environmental conditions, with the concentrations of capsaicin
increasing with plant stress factors such as drought, high temperatures,
high EC and high salinity. This gives a hydroponic grower great scope
to influence and manipulate the flavor quality and heat of their chile
fruit. Capsaicin concentrations also increase through out the
development of the fruit and are always highest at maturity.
Chile Pepper Varieties
Within the capsicum genus there are over 300 different chile peppers
grown around the world. Most fall within the Capsicum frutescens or the
Capscium annuum species, although others do exist. Chile varieties can
range from the mild Hungarian wax to the explosively hot habanero.
Habanero chiles, the hottest in the world, come in green, yellow, orange
or red and these are used extensively in food preparation in central
America and the Caribbean. Congo peppers and Scotch Bonnets are also
types of habaneros. The yellow Hungarian wax is a large, fleshy chile
with mild to medium heat and a good flavor. Cayenne peppers are long,
thin tapering chiles which change from bright green to intense red at
maturity these are used in many Asian and Indonesian countries and are
also used crushed and powdered in dry form as Cayenne pepper. Jalapeno
peppers are small very hot chilies with dark green fruits, turning red
at maturity - these are popular peppers in Mexico and California for
cooking. Serrano chiles are more popular in Texas and South America to
make savory hot pickles and fiery sauces. Thai hot peppers have a
distinctly hot flavor and are used in many Asian dishes. Tabasco chiles
which are the main ingredient in the famous hot sauce, are used in
Creole cooking. Tabasco chiles have a unique hot, dry, smoky taste and a
distinctive flavor making them a popular choice for many hydroponic
growers. There are many other less commonly grown chile types such as
the Bulgarian carrot chile, large hot cherry, Filus blue, fire cracker
piquin chile, the strangely shaped peter pepper, variegated chiles,
Jamaican hot and rocoto-Manzano chiles to name a few. Most vegetable
seed supplies have a good range of hot chiles to chose from and seed
mixtures containing a range of different varieties are often a good way
to start a chile plant collection and select the best types for a
hydroponic garden.
Growing Hydroponic Chiles
Chile pepper plants are easily raised from seed for hydroponic cropping.
These are best sown into cells of inert media such as oasis or
rockwool, or into small pots for later transplanting into hydroponic
systems. Chiles have a high heat requirement for germination - in the
range 22 - 28 C, with an optimum of 25 C. At 25 C chile seeds will take
about 6 days to show the first signs of germination. Some varieties of
chiles are slow to germinate, but this can be overcome by storing
freshly harvested chile seeds at 24 C for 2 - 3 weeks before sowing.
Slow emergence in chiles can also be prevented by delaying extraction of
the seeds from the fruit for 10 days after the fruit have become fully
ripe. For example, seeds from the Tabasco pepper can have germination
rates increased from 40% to 70% by storage of the seed for three weeks
prior to sowing.
After germination, temperatures can be reduced to 20 - 25 C to harden
the seedlings off before transplanting into the hydroponic system. Chile
plants are fairly temperature dependent, and good vigorous growth will
only be achieved under warm conditions with high light levels. Generally
night temperatures need to be lower than the day temperature (25 C day/
18 - 20 C night are ideal), for good plant growth. High night
temperatures cause problems with flower and fruit- let drop, although
this is largely dependent on the type of chile being grown. Seedlings
can be given a half strength (EC 0.8 - 1.0) vegetative nutrient solution
from the time of the development of the seedling leaves until a week
before planting out. Full strength nutrient (EC of 2.0) should be given
to seedlings before planting into the hydroponic system to assist with
hardening the plant off. Seedlings raised under artificial lighting only
should be exposed to maximum light levels in the week prior to
transplanting if possible to give the plants time to adjust before
establishment into the hydroponic system. Where chile plants are to be
grown under grow lights only, the smaller, more compact varieties have
been shown to perform well and make the most efficient use of both light
and space.
Most chile plants, like the larger capsicums, are rather slow growing in
the early stages (30% slower than tomato plants in fact), but they can
be kept growing and producing for many months as a perennial crop if
conditions remain warm enough. Chile plants are best pinched or pruned
to create a compact bush shape in hydroponic systems which then does not
require support or further training. Once the plant has become
established in the hydroponic system flowering will occur early on in
the plant's life and most chile varieties will produce large numbers of
flower buds and fruit. While pollinators such as beneficial insects and
bees are not required for fruit set in chiles, the plants do benefit
from pollination assistance - tapping or gently shaking the plants when
in flower will release pollen and promote fruit set.
Once the chile plants have begun to set the first fruit, the nutrient
formula can be gradually changed over to a full strength 'bloom' or
'fruiting' formula to support the development of the fruit. While this
is beneficial, many chile plants have been grown on a standard general
purpose nutrient formula in mixed systems containing salad greens, herbs
and other plants. A good nutrient formula which will support maximum
levels of vegetative and fruiting growth in hydroponic chile plants
would contain the following levels of nutrients:
Nitrogen 302 ppm, Phosphate 103 ppm, potassium 364 ppm, magnesium 96
ppm, calcium 330 ppm, sulphur 174 ppm, iron 4.90 ppm, manganese 1.97
ppm, zinc 0.25 ppm, Boron 0.70 ppm, Copper 0.07 ppm, molybdate 0.05 ppm.
Most varieties of chile plants will produce large numbers of individual
fruits, however the number and size of these depends on the type grown.
The large fruited Hungarian wax, obviously will produce less fruit than a
cultivar such as 'Thai Hot' which has many small (5-10 mm) fruit. The
heat and flavor of hydroponic chile fruit can be influenced by the
grower - chiles grown in warmer conditions produce more 'heat' or fiery
compounds in the fruit flesh than those grown under cooler conditions.
High light also promotes color development in the red and orange
varieties (carotenoid pigments) and this increase in color is associated
with strong flavor. Chile plants grown with inadequate light will have a
more diluted color, flavor and pungency. High levels of potassium are
required to produce firm, crisp fruit flesh and also assist to prolong
the shelf life of the harvested fruit. Potassium also plays a role in
the flavor of the fruit. Running moderately high EC levels in a chile
hydroponic system will have a noticeable effect on the fruit, as will
maintaining a slight moisture stress in media based or flood and drain
systems. Both high EC (above 3.0) and moisture stress, which can be
maintained by allowing the media to dry slightly between irrigation's of
nutrient solution, have the effect of concentrating the flavor and heat
in chile fruit and this technique is well worth the chile connoisseur
experimenting with.
Pests and Diseases
Hydroponic chile plants are prone to much the same pests and plant
diseases as other hydroponic crops. Whitefly, aphids, caterpillars,
mites and thrips can call cause problems on chile plants. Some species
of caterpillars will chew large holes into chile fruit, the heat of the
fruit flesh does not deter these insects since they don't have the same
ability to taste hot compounds as we do. Control of most of these pests
can be obtained with the usual pesticide products - Neem oil is
particularly effective if used on a regular basis and safe to use on
food crops. Soap and oil sprays which smother soft bodied insects are
also another safe option for small numbers of plants.
Chiles are also prone to diseases such as damping off (Pythium),
Botrytis under conditions of high humidity, fusarium, bacterial leaf
spot and soft rot and certain virus diseases Generally growing chile
plants in a warm environment and preventing excessive humidity levels
(above 90%) will prevent many fungal diseases. Keeping the foliage dry
at all times prevents many of the bacterial and fungal pathogens from
become established and preventative sprays of sodium bicarbonate and
silica products will also give a good degree of disease prevention.
Hydroponic chiles are generally a trouble free and highly rewarding crop
to grow. They take up minimal amounts of space and provide the greatest
amount of culinary 'heat' per plant than just about any other crop.
Chile plants are also highly ornamental with a spectacular range of
shapes, sizes and colors making them an essential for any hydroponic
garden.