Sowing Rhododendron - looking for advice from expert growers?

[Corrado & Rina]

Dear all,

From the seed exchange I got some very interesting Rhododendrons, and I would now like to sow them as soon as possible.

I have no experience of growing Rhododendrons from seed. Anyone who can help with sound advice?

I have seeds of the following:

Rhododendron charitopes tsangpoense
Rhododendron hirsutum
Rhododendron pumilum
Rhododendron saluenense

Best,

Corrado

[Maggi Young]

See this thread : http://www.srgc.net/forum/index.php?topic=12675.0

[Maggi Young]

Rhododendron charitopes tsangpoense
Rhododendron hirsutum
Rhododendron pumilum
Rhododendron saluenense

   Great choices, by the way!  Those are all seriously attractive rhodos.

[Corrado & Rina]

   Great choices, by the way!  Those are all seriously attractive rhodos.

Thanks a lot Maggie! Still looking for ferrugineum and sinogrande ....

I looked at your recommendations and at most of the tests on sowing, but they seem to suggest slightly different things ..., but I am not sure I found an answer to all my questions.

1) Do we need to give them a cool period in the fridge first?
2) Do you need to scarify them?
3) Do you need to pre soak?
4) Can we use peat free compost made of very fine pine bark wit a PH of 5.5 or is it better to add sharp sand (we have gone peat free)?
5) Do you cover them or surface sow?
6) How wet do you normally keep them?
7) How warm do you keep them?
Do you need to cycle them (warm by day cold by night)?
 
Best,

Corrado

[Maggi Young]

Rhodos prefer compost that is on the acid side of neutral.  How you accomplish that is  up to you. We use our own leaf mould  in a our  mix with gives a naturally slightly acid mix since we stopped bothering  to sow on sphagnum moss.
Sow the  seed  near the surface, cover very lightly with gravel and set outside somewhere where  the pots can remain undisturbed- covering with chicken wire to prevent disturbance by birds  if you do use moss.
 Then just sit back and wait for them to grow. All the effort that is put in by those growing in less favourable climates, where pots need to be indoors,  with lights etc are not needed in the UK.   We sit all seed pots out on a sand area that is quite protected from too much wind  and let nature take its course - it will work!

[GordonT]

Here is a Rhododendron seed sowing guide put together by Bill Wilgenhof and Sharon Bryson of the Atlantic Rhododendron and Horticultural Society here in Nova Scotia. http://www.willowgarden.net/page2/ARrhodosfromseedeasyway.htm

[Maggi Young]

Fine advice in that article for those conditions - but our very simple methods are very effective in the UK.

[Corrado & Rina]

Fine advice in that article for those conditions - but our very simple methods are very effective in the UK.

Let's see if I got that right:







One case like ARS to see how it goes



For compost I used fine bark for seed with PH 5.5 and covered with aquarium grade grit.

What do you think?

Best,

Corrado

[Maggi Young]

 I would want the pots  sitting on sand and  in a flat seed tray like that that is even more important to give a level of protection from severe frost.  On a wire shelf like that the tray will be much too liable to drying out and freezing. On sand,  tucked near the foot of a shrub, perhaps, where it  will still get  rained on  while gaining a little protection would be much better than how you show.

If you look in any of Ian's Bulb Logs where he shows  seed frames, you'll get a better idea of how we do it.  Our seed frames are to the west of the house and are in an enclosed area ) where they are open to the elements  (they  can be covered over if there is prolonged wet weather  but this hardly ever happens even here in Aberdeen !)

[Corrado & Rina]

I would want the pots  sitting on sand and  in a flat seed tray like that that is even more important to give a level of protection from severe frost.  On a wire shelf like that the tray will be much too liable to drying out and freezing. On sand,  tucked near the foot of a shrub, perhaps, where it  will still get  rained on  while gaining a little protection would be much better than how you show.

If you look in any of Ian's Bulb Logs where he shows  seed frames, you'll get a better idea of how we do it.  Our seed frames are to the west of the house and are in an enclosed area ) where they are open to the elements  (they  can be covered over if there is prolonged wet weather  but this hardly ever happens even here in Aberdeen !)

Will do .... what is the germination time in UK in these conditions?

Regards

Corrado

[Maggi Young]

That I don't know - we don't keep such records        Someone else is bound to though !

[johnw]

1) Do we need to give them a cool period in the fridge first? - No
2) Do you need to scarify them? - No
3) Do you need to pre soak? - No
4) Can we use peat free compost made of very fine pine bark wit a PH of 5.5 or is it better to add sharp sand (we have gone peat free)? - I use finely chopped live green sphagnum moss, second best sterlized pure coarse peat.
5) Do you cover them or surface sow?  - surface sow, they light to germinate
6) How wet do you normally keep them?  - moisten medium, sow, mist, place in a plastic bag under lights, ,mist if surface appears at point of getting dry.
7) How warm do you keep them? - +20c
Do you need to cycle them (warm by day cold by night)? - No

They will germinate in 3 weeks, at the second true leaf transplant into an acid mix and graaaaaaaaaaaaadually acclimatize to the real world after fully established and growing.

As soon as pumilum germinates reduce temp to 15c, eventually it will want a good portion of pumice in the mix. It can be very tricky.

john

[Maggi Young]

I love this - we don't keep our house to 20c for us, never mind produce that much heat for plants! 

Diffr'nt strokes, eh? !!

[Corrado & Rina]

1) Do we need to give them a cool period in the fridge first? - No
2) Do you need to scarify them? - No
3) Do you need to pre soak? - No
4) Can we use peat free compost made of very fine pine bark wit a PH of 5.5 or is it better to add sharp sand (we have gone peat free)? - I use finely chopped live green sphagnum moss, second best sterlized pure coarse peat.
5) Do you cover them or surface sow?  - surface sow, they light to germinate
6) How wet do you normally keep them?  - moisten medium, sow, mist, place in a plastic bag under lights, ,mist if surface appears at point of getting dry.
7) How warm do you keep them? - +20c
Do you need to cycle them (warm by day cold by night)? - No

They will germinate in 3 weeks, at the second true leaf transplant into an acid mix and graaaaaaaaaaaaadually acclimatize to the real world after fully established and growing.

As soon as pumilum germinates reduce temp to 15c, eventually it will want a good portion of pumice in the mix. It can be very tricky.

john

Thank you John, very interesting. I am going to put together a proper fact sheet, when this discussion finishes.

Why don't you put them into a propagator instead of plastic bag? Maybe even with some sort of low heat from the bottom?

Regards

Corrado

[johnw]

Thank you John, very interesting. I am going to put together a proper fact sheet, when this discussion finishes.

Why don't you put them into a propagator instead of plastic bag? Maybe even with some sort of low heat from the bottom?  Regards Corrado 

I'd set the plastic bagged pot on bottom heat but only de-bagged if a mist system were running.  Once those roots get dry i's the end. 

18c is ok too and even 10-15c - just means germination will be slower in Scottish abodes.