Re: Tiny tubers (was: seedlings that refuse to develop)

You can expect losses over the first summer, especially if they are
already dormant. The main problem is management of moisture: too much and
the tuber rots, or not enough and it dies from desiccation. I grow
more bulbs than tuberous dicots like these delphiniums, but the
principles for handling the seedlings are similar.

First, the seedlings of geophytes [plants that die down to bulbs,
corms, tubers, etc] are opportunistic, more so than the mature plants.
Even though there are only cotyledons [or, in many cases, one or two true
leaves], the seedling will delay going dormant for some time if it doesn't
experience stress from drying out or excessive heat. The longer they stay
in growth, the larger the storage organ is.  This means better survival
and much less time from seed to bloom.  

I grow hundreds of seed lots every year, so most of my seed goes in flats
of small pots, mostly 4 inches.  This is NOT ideal for subjects like bulbs
[and tubers]. In general these are best left undisturbed for a full year
-- pricking-out will usually cause them to go dormant too soon. Also, for
best growth, most geophytes benefit from more soil than available in small
pots or flats.

So, the best thing is to plant in containers of at least one gallon, with
soil depth of at least 4 inches [10 cm].  Keep watered, and I recommend
using a dilute balanced liquid fertilizer regularly; continue watering
until foliage is yellowing, then wean off.  When foliage is dead, store
the container in a relatively cool place -- I have a room in my basement
that stays at 15-22 C [60-70 F] all year, and the dormant bulbs go there.
Alternatively, grow in large clay pots and plunge to the rim in sand,
water about once a week through the summer.

One of the best systems that I've seen for lots of 50-100 seeds was used
by a friend who grew western American Erythroniums:  These often take up
to 7 or 8 years from seed to bloom, but he was able to get flwering plants
in 3 years or less,  He used styrofoam boxes, obtained from local fish
markets.  He punched drainage holes around the bottom of the box, and
added at least 6 inches [15 cm] of peat-perlite compost.  Seeds were
planted on the surface in early autumn, covered with about 1/8 inch [3 mm]
of crushed granite poultry grit, and left out in the winter.  When
germination ocurred, he moved the open box into a yard with overhead
irrigation, fertilizing 1-2 times weekly in the irrigation.  When leaves
went dormant, the bulblets were already 3 inches down, and he simply let
the box dry out for several days, then put the styro lid on and stored the
box in his garden shed until autumn.  The bulbs were grown to flowering
size without being moved out of the seed boxes.  

*****
If you have a smallish container with tubers [bulbs] already dormant, I'd
suggest [after verifying that that there's life!] slipping the compost
with as little disturbance as possible into a gallon container of the same
compost.  Add a layer of grit or 1/2 inch of compost on top, water lightly
once, then store in a cool place until autumn -- then be sure to put it
outside...

loren russell,corvallis, oregon


On Fri, 26 Apr 2002 susannah@cyber-dyne.com wrote:

> Lauren and Branka --
> Yes, yes!  I dug up one of the dead-looking ones, and there is a little 
> tuber, about the size of a sweet pea seed, but pointed.  Other than that, 
> there's only one root, about an inch long.  I am so grateful for the help 
> of you wise people!  If not for you, I would have just thrown out this 
> whole tray of seedlings.  And now for my next question: What do I do 
> now?  Are they really supposed to be dormant in the summer, or do they 
> think this is winter because I started them in December?  Should I give 
> them a fake winter in the fridge, or let them dry out like summer, or 
> ???  If no one knows, I guess I'll split them up and try different things 
> with different batches.
> Gratefully yours,
> -- Susannah
> 
> 
> 
> Loren Russell wrote:
> ...a few of our native delphiniums, notably the rare D. pavonaceum and D. 
> menziesii [the latter widespread and common] do stop at the cotyledon stage 
> and put their all into building a resting root structure [tuber].
>
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