Maximum Yield Australia/New Zealand March/April 2019 | Page 37

Once sprouted, the plant goes from one extreme to the other;
from its most durable stage to its most vulnerable.
Starting Seedlings
Seedlings can wither and die in a matter of hours without
proper moisture. They don’t have an extensive enough root
system to reach very far within the growing medium to take
advantage of large containers, and as such are frequently
started in smaller containers, then transplanted as they
increase in size. Nursery pots sized to fit 1020 trays are a
common choice, as are plastic beverage cups.
Seedlings planted directly outdoors should be well marked
and protected from flooding or other traumata. Markers or
garden maps can be helpful in ensuring each mature plant
can be identified if multiple varieties of the same type of
plant are grown. While it can be obvious to visually tell the
difference between a squash sprout and a tomato sprout,
telling the difference between similar tomato varieties can
be difficult before fruit set, so keeping a record is handy.
Dos and Don’ts for Pre-Veg Seedlings
• Overwatering can be as detrimental as giving too little
water. Aside from the potential to drown the plants if kept
in stagnant water, an abundance of moisture or humidity
can lead to a fatal fungal infection known as “damping
off,” which is generally considered untreatable once
infected.
• Seedlings require light to grow, but high-intensity
discharge lighting can be detrimental. Of particular risk
is heat damage, which can not only overheat the plant
directly, but can cause indirect damage by drying out the
grow medium.
• Their small size means they are more susceptible to
physical attacks and mishaps than established plants.
Even a single insect bite that would go practically
unnoticed on a larger plant can put an end to a tender
seedling.
• Errors in nutrient solutions are magnified when dealing
with seedlings. Nutrient solutions for seedlings should
be kept mild and simple. They are not tolerant of
overfeeding and are particularly susceptible to nutrient
burn and negative reactions from intense additives.
“
Seeds
sprout when environmental
conditions are favourable and
moisture enters through small holes
in the seed coat called micropyles.”
• Particularly in the case of moving indoor-grown
seedlings to the outdoors, hardening off can help reduce
the stress from a change of environments. One approach
to hardening plants is taking them outside during the
mildest part of the day for an hour for the first day, and
for an additional hour each consecutive day (two hours
on the second day, three hours the third day, etc.) for a
week to 10 days. By giving the plants time to acclimatise
from their (hopefully) idyllic indoor conditions to
the harsher realities of outdoor life, the shock of the
experience can be mitigated and the stress reduced.
Hardening off is generally not required when moving to
a milder environment, so outdoor plants can be moved
indoors (after a quarantine period) with relative safety.
• Similar to hardening off, if the seedling will be grown
under harsher high-intensity discharge indoor lighting, it
is less stressful to gradually increase the intensity over a
period of time than making a harsh transition to the new
environmental conditions. This can be accomplished by
first moving to the periphery of the lit area for a few days
before placing directly under the lighting fixtures.
It behooves a gardener to take particularly good care of
their seedlings, as they are the tender starts to robust
mature plants. Healthy seedlings enjoy a more vigorous
growth spurt from transitioning into adulthood, whereas
sickly starts can take additional time to recover from their
retarded development before maturing.
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