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Seedling media posting with permission


Date:    Mon, 10 Mar 1997 22:21:03 EDT
From:    John Lonsdale-1 <John_Lonsdale-1@SBPHRD.COM>
Subject: Seedling media

<<<<<Jim Mc Coy, zone 5, Northwest New Jersey
How soon after germination should seedlings be moved out of a
pure Turface growing medium?  Also, what soil mix do you rec-
comend for growing on?  This is my first time growing plants
from seed and I've been having trouble with the moisture levels
in a peat based mix (either too wet or so dry that the mix would
not take up the water.  I'm looking for an easier way and would
appreciate any help I can get.>>>>>>

I have never used Turface but it seems to work OK for Jim McClements.  I
appreciate that it has excellent water and air holding capacities and seems OK
for germinating many things, especially finer seeds.

Coming from a high alpine background, where poor drainage is the root cause of
all evil (no pun intended) I have a natural suspicion for any technique which
requires leaving pots in standing water, particularly after germination.  The
oxygenation and general quality of standing water is much poorer than fresh
rain water moving down through the pots and away.

If you want to use Turface then I would suggest you move seedlings on as soon
as the cotyledons are well developed - I do this anyway with most alpines
except bulbs which are left for one or usually 2 seasons.  You will do far less
root damage and ensure faster establishment if you move the seedlings very
young, though they obviously need TLC for a while afterwards.  Leaving growing
seedlings in seed pots for too long is a recipe for disaster - no amount of
extra feeding will help much.

I sow (here in the US) onto the surface of a 50:50 mixture of Pro-mix compost
and mid-sized Grani-grit (unsurprisingly, granite grit - very sharp and about
3mm average size).  Seeds are sown directly on a lightly firmed surface and
then covered with 0.5-1cm of pure grit, watered thoroughly then put outside
with full exposure to the elements.  The grit layer is less for primulaceae and
other light sensitive species.  Move the seedlings under protection as soon as
they are up and prick-out asap.  Before pricking out dry the pots out so they
are just moist - you will find the seedlings come out much more easily and with
less damage.  Another often used mixture is peat and sharp sand 2:1 or 1:1.
Take your pick.

I have used this technique for dionysias, androsaces, raoulias, saxes, a huge
range of 'bulbs', woodlanders, primulas, cyclamen etc.  They all get the same
seed mix but obviously they get moved into something slightly different as they
get going - although all of the above ended up in not more than 3 basic mixes
for growing on.  The compost for growing on obviously has to be suited to the
needs of the plants but it is also vital that it suits you as well.  For
example you will grow wonderful dionysias in a compost with 80% grit in it (as
I used) but you will have to be prepared to water it every day, even in plunged
pots and repot once or twice a year, with maybe a supplemental feed or two
before and after flowering.  If you are not around for days or weeks on end you
can reduce the grit but the plants will suffer and you will lose a lot more
over time and the ones you keep will have more botrytis etc.  Even with plants
that will end up in the garden I would use 50% grit whilst they were potted.

Remember to look after the roots first - good roots mean a healthier plant -
poor roots predispose all plants to anything and everything bad.  There should
be classess at all AGS shows for healthy roots.

Hope this helps. John.

Exton, Pennsylvania, Delaware Valley NARGS, Zone 6b, USA.
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