Compared to cuttings, seeds are relatively quick to plant and are less
likely to carry pests and disease.
Collecting seeds:
As with cuttings, seeds should be collected from a plant that has been well
maintained, has favourable characteristics (e.g. yield, visual appeal) and
is free of disease. Seeds should be collected when mature. Seeds that are
immature will not germinate when planted. Immature seeds are soft and
generally paler in colour compared with mature seeds of the species.
Seed storage:
It is important to note that a seed is living. To suppress germination but
maintain the seed in a dormant state, storage conditions should be
maintained as follows:
+ Cool
(2-8oC
/ 36-46oF).
+ Dry
conditions with limited oxygen supply – via screw topped glass jar.
+
Darkness.
Medium:
The choice of growing medium is essential. It should
provide high oxygen and water levels, and good drainage.
Disease:
Sterilization of hardware and media before and during the propagation
process is paramount. Maintaining adequate ventilation is also essential
for minimizing the threat of disease outbreak.
PROCEDURE
Step 1.
Thoroughly wash (i.e. sterilize) all hardware and areas that are likely to
contact seedlings and cause disease contamination.
Step 2. To
increase the success rate of seedlings, use a ‘heat mat’ and ‘propagation
lid’ (vents closed) to maintain root and air temperature at 20-25oC (68-77oF) and
relative humidity at ~80% (Fig 4.2). Note that cool conditions delay the germination
of most seeds making them more susceptible to fungal attack.
Step 3.
Pre-soak medium with TwinTech Fertilizer. This ensures excess alkalinity is
removed (lowers the pH) and the medium is bedded down. Allow
to drain.
Step 4.
Option 1.
It can be
beneficial to pre-germinate seeds prior to planting in the medium. To
do this, place them between moist tissue on a plate. Cover this with
an up-turned plate (i.e. seeds must be kept in dark). Check every few
days, ensuring that the tissue does not become dry – sprinkle with water as
necessary. Once the root (i.e. radical) becomes exposed, place upright
(root pointing downwards) in medium ~2-5mm (1/8 inch) below the surface.
Option 2.
Sow seeds at a depth equal to 2 ˝ times their diameter. Cover the seed with
medium and gently tamp down.
Step 5.
Immediately after planting, lightly re-water using water or dilute nutrient
mix (e.g. use a combination of TwinTech Fertilizer and
TwinTech Plus; EC
~0.8mS). Continue to water the medium as required, typically every 2
or 3 days. Ensure to maintain root and air temperature at 20-25oC
(68-77oF) and relative humidity at ~80%. Diligently remove any dead
leaves or seedlings - these are an ideal host for fungi.
Note:
Some plant varieties (or mediums) may require little or no nutrient until
the first few 'true' leaves appear (Fig 4.8b). Hence if the success rate is poor, try
feeding with water containing just TwinTech Plus.
Step 6.
Remove the ‘propagation lid’ once the first shoot appears (Fig 4.8a). Continued high
humidity and poor ventilation will encourage fungal diseases.
Step 7.
Light is not required during the actual germination process. However,
once the first shoot (‘plumule’) begins to appear (Fig 4.8a) the seedlings
need good light to begin photosynthesizing and prevent the plumule from
becoming spindly or ‘etiolating’. Use low intensity lighting for the
first few weeks of growth. Preferably use cool white fluorescent
lights and position ~10cm (4 inches) above the plants.
Step 8.
Gradually expose the seedlings to their proposed environment - depending on
the plant variety this may take only a few days or many months. As such,
begin to gradually increase light intensity and nutrient strength (to EC
~1.2mS). Ensure these changes are gradual as a sudden change might kill
them.
Step 9.
Healthy seedlings grow quickly and therefore it is essential to transplant
them into a bigger system (or container) that provides adequate room for
further root and shoot growth. Do this only after a minimum of 2 ‘true
leaves’ have formed (Fig 4.8b). If the seedling is left in its current position for
too long the roots may grow long enough to become
tangled.
