Norton wrote
> I have been germinating begonias from seed. The species I?m growing are
> Begonia geraniifolia and Begonia octopetala, both grow in any of the
> "Lomas" of Peru near the coast and in some parts of the Andes in more
> elevated areas. There is not much information about them. They are tuberous
> begonias and the tubers are very superficial.
>
> They took a month to germinate and I?ve seen them get bigger in the main
> leaf, but on the first three months the tuber has only gotten as big as a
> quinoa seed.
>
> >Is this normal? Do they need more light maybe? How can I make them grow a
> bit faster?
>
> > I read on the internet that when they have 3 leaves you can start giving
> them one drop of fertilizer( fish emulsion) directly to the tuber, once
> every 2 weeks to help them develop , is this true?
>
I haven't grown these, but this is how I would think about them:
If prehistoric Peruvians grew them as a food crop, they are probably very
easy to grow. If they don't seem that way I would think I'm doing something
wrong. Maybe you can research food growing technology of the ancients?
In general, things from winter-rainfall areas grow fastest when they get
plenty of water and as much light as they can tolerate without getting too
hot.
Next is only a suspicion I have: I think a lot of these plants live along
with cyanobacteria that fix nitrogen for them. There is no other source of
nitrogen for these plants, and they grow much faster in real soil in a real
winter rainfall situation than they do in a pot of sand on a windowsill.
So, despite constant admonitions from people not to fertilize
winter-rainfall plants, I do so heavily! With ammonium sulfate! I put a
spoonful / 15ml of powder in 3.78 liters of water (1 gallon.) I use this as
often as I have time to do so. I would fertilize all my winter bulbs with
this at every watering but I have that pesky need to work. Be careful with
solute load in water. I don't know whether lomas vegetation plants can grow
with high total dissolved solids in their water. Too much fertilizer may
cause osmotic damage ("burning") but I don't know.
Begonias grow like weeds so long as temperature be appropriate and water
available. I would expect a lot of winter-growing things to become dormant
if they dry out even once.
I would seek out experienced tuberous begonia growers to find out when
other kinds begin forming tubers from seed. I have no idea; I've only grown
non-tuberous begonias from seed. A wild guess for a plant with an
unpredictable rainfall pattern is that it would produce as much vegetative
growth as possible after seeds sprout, in order to take advantage of
photosynthesis, to make as much sugar as possible while water is available,
and then it would form tubers later, in response to a day length signal or
the first hint of reduced water availabilty. But as always, a beautiful
hypothesis can be slain by an ugly fact.
Leo Martin
Zone 9?
Phoenix Arizona USA