Babiana rubrocyanea

Michael Mace michaelcmace@gmail.com
Tue, 13 Jan 2015 09:55:30 PST
Hi, Makiko.

Thanks for answering my questions. I will give you some ideas below on what
might be wrong, but first I should tell you that I am not a botanist or
scientist. I can guess about what's happening, but I don't know for sure.

One possibility to think about is frost. LA had some cold weather at the end
of December. Is it possible that your plants froze? One way to check that
would be to look for damage on other tender plants nearby. For example, if
the citrus trees in your neighborhood have been damaged by frost, it may
have been cold enough to hurt the Babianas. However, usually a freeze like
that would cause the whole seedling to wither all at once. So I suspect
that's not it.

When leaves on a bulb die back from the tip, I usually suspect that
something has damaged the roots. When the plant is healthy, I think the
roots and leaves grow at the same time and are in balance with each other.
If the roots are damaged, the plant can't support all of the leaves, and
some of them die back, starting at the tips of the older leaves.

The difficulty is that roots can be damaged by several things. The soil
could be too waterlogged, or it could be too dry. There may also be a fungus
at work damaging the roots. All of those problems could look the same in
terms of what they do to the leaves.

Are the dying plants in your plastic pots, or the terra cotta ones, or in
both types of pots? I ask because terra cotta pots dry out much faster than
plastic ones. Especially in SoCal, even a large terra cotta pot could get
too dry. On the other hand, if you're using black plastic pots and the sides
of the pots are in the sun, the pots could be getting too hot during the
day. In that case the plants will get cooked.

But usually the thing to look at is the soil. You said you're using mostly
decomposed granite, which I think would usually be very well aerated. But if
it has a lot of fines (dust) in it, air might not be getting to the plant
roots and they will suffocate. This is the most common problem for bulb
growers.

When you water the pots, how quickly does the water drain through them? Does
the water disappear immediately and run out the holes on the bottom, or does
it form a pond on top of the pot and gradually drain through? The longer it
takes for the water to run through, the more likely that your soil is too
compact and the plants are drowning. If this is the case, I would water less
often (once a week should be enough), and also treat the pots one time with
a fungicide (get one that you can mix with water, and use it in the next
watering).

If water drains through the pots very quickly, then aeration is probably not
your problem. I'd suspect that maybe the plants got too dry at some time
(which would kill the roots fast), or that one of the other problems I
listed above was the cause. In this case, keep the sides of the pots out of
direct sun and water them more often.

If your Babiana rubrocyanea do not survive, feel free to send me an e-mail
this summer, and I'll send you a few bulbs of them. They grow well here in
San Jose, so they can also do well in Los Angeles once we get the soil,
water, and temperature right.

Good luck,

Mike
San Jose, CA





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