Hardening off alder seedlings
 

Since January I have been growing alder seedlings under light - and
all the time awaiting the gentle touch of a policeman on my shoulder
concerned about my electricity bills! The plan is to grow them up to a
size where they could be grafted onto the cone-bearing spurs of adult
trees.

I have started to reduce the lighting from 24 hrs to something nearer
12 hrs. The temperature inside the light box is about 22 °C. The
seedlings are now about 20 cms high and about 3 leaf pairs down from
the top the stems are about 2 mm across. The seedlings are growing
individually in a seed-tray with cells 4 x 4 cm x 8 cm deep.

Obviously I now have to think about hardening them off to survive
outdoors. Any suggestions? I remember my mother used to use cloches in
such circumstances, but she's long dead now. Would they be of use?

Michael Bell

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Hardening off alder seedlings
 

In message
Chris Hogg wrote:

On Sun, 10 Apr 2011 10:49:39 +0100, Michael Bell
wrote:

Since January I have been growing alder seedlings under light - and
all the time awaiting the gentle touch of a policeman on my shoulder
concerned about my electricity bills! The plan is to grow them up to a
size where they could be grafted onto the cone-bearing spurs of adult
trees.

I have started to reduce the lighting from 24 hrs to something nearer
12 hrs. The temperature inside the light box is about 22 °C. The
seedlings are now about 20 cms high and about 3 leaf pairs down from
the top the stems are about 2 mm across. The seedlings are growing
individually in a seed-tray with cells 4 x 4 cm x 8 cm deep.

Obviously I now have to think about hardening them off to survive
outdoors. Any suggestions? I remember my mother used to use cloches in
such circumstances, but she's long dead now. Would they be of use?

Michael Bell

One of the first things they'll need to get used to is proper
daylight, otherwise they'll burn up. Even daylight filtered through
glass isn't the same as natural daylight. I would start by putting
them outside for say an hour at a time, not in direct sun, to get them
used to the UV etc. Gradually increase the time outside until they're
out all day. You can then try leaving them out on mild nights as well,
until you eventually leave them out all the time.

I left them out all this afternoon (VERY bright sunlight) under a
plastic cloche and looked for signs of leaf droop, but there were
none. I took them in tonight.

I'll try them for an hour or so in the open without the cloche, is it
OK to look out for the leaves starting to droop and covering them
again if they droop.

I doubt if we'll have frost again (I live in Newcastle on Tyne, 10
miles from the sea) at what temperature are they at risk overnight?

Regards

Michael Bell

--

Hardening off alder seedlings
 

In message
Chris Hogg wrote:

On Sun, 10 Apr 2011 21:45:02 +0100, Michael Bell
wrote:

In message
Chris Hogg wrote:

On Sun, 10 Apr 2011 10:49:39 +0100, Michael Bell
wrote:



One of the first things they'll need to get used to is proper
daylight, otherwise they'll burn up. Even daylight filtered through
glass isn't the same as natural daylight. I would start by putting
them outside for say an hour at a time, not in direct sun, to get them
used to the UV etc. Gradually increase the time outside until they're
out all day. You can then try leaving them out on mild nights as well,
until you eventually leave them out all the time.

I left them out all this afternoon (VERY bright sunlight) under a
plastic cloche and looked for signs of leaf droop, but there were
none. I took them in tonight.

I'll try them for an hour or so in the open without the cloche, is it
OK to look out for the leaves starting to droop and covering them
again if they droop.

I doubt if we'll have frost again (I live in Newcastle on Tyne, 10
miles from the sea) at what temperature are they at risk overnight?

Regards

Michael Bell

It's not leaf droop that you'll see, in fact you probably wouldn't see
anything immediately. It's like sunburn, it doesn't show up straight
away, but over a period of few days the leaves may go brown and
shrivel. I'm no expert at alder seedlings, and they should be fairly
tough, but as you've invested a lot of time and effort in them, I'd
treat them gently and with caution. Keep them out of direct sun, and
bring them in at night for a few days and if frost is forecast.

I gave my seedlings 4 hours of full sunshine yesterday (and it was a
blazing hot day) and today is overcast with a little drizzle, so I
don't think I am risking them too much. Thanks for your input.

Michael Bell

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