rhododendron seed starting

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RickR
Title: Moderator
Joined: 2009-09-21

A wealth of other info on that site, too.  Thanks for sharing it.

And welcome to the forum, Bill!

Rick Rodich    zone 4a.    Annual precipitation ~24 inches
near Minneapolis, Minnesota, USA

Tingley
Title: Member
Joined: 2013-01-07

I have a question about Rhododendron seed longevity. Since my efforts to find plants of Rhododendron augustinii for sale in Nova Scotia have been fruitless, I went looking for seed sources. Van Dusen Botanical Garden in Vancouver, BC has packets for sale, but they were collected in January of 2009. R. augustinii is high on my wishlist, so I am tempted to order a packet anyway, but wonder if the seed would simply be dead at this late date. Does anyone have any advice, or a source of fresh seed I could contact?

Southwest Nova Scotia, zone 6b or thereabouts

Diane Whitehead
Title: Member
Joined: 2009-12-11

Gordon,

I have about four clones of augustinii.  I don't think I got them all deadheaded so there ought to be seeds for you.  Or, since you're in Canada, I could just mail you a batch of cuttings.

Diane
Victoria

Tingley
Title: Member
Joined: 2013-01-07

Thank you Diane, I am looking forward to germinating seed from your plants, and possibly attempting cuttings as well! Hopefully a few plants will come of all this... love seeing new plants work their way into the landscape. Last years' seedlings were Digitalis obscura and Kniphofia triangularis. A few Enkianthus sp. seedlings have germinated, along with Poncirus trifoliata.

Southwest Nova Scotia, zone 6b or thereabouts

Gene Mirro
Title: Guest
Joined: 2010-02-25

Gordon, if van Dusen stored their seed in the freezer, it will be as good as the day they froze it.  If they stored it in the fridge, it might still give some germination.  If they stored it at room temperature, it will give very poor germination, if any.

See http://nargs.org/smf/index.php?topic=635.0 for my method of growing Epigaea repens.  I now grow Azaleas, Rhodies and Oxydendrum arboreum using exactly the same method.  It's very similar to Todd's method, except my mix is a lot "dirtier".  The plastic bags can be replaced by transparent propagation domes if you are using 10" x 20" flats.  I really like the 4" tall domes made by NGW, model number 726239: http://www.sunlightsupply.com/p-11762-ngw-propagation-domes.aspx .  Ignore the part number in the photo; it's a typo.

The method with the plastic bags and fluorescents is so bulletproof that I am now growing almost everything that way.  I don't see any damping off using this method; I can't explain it.  But keep a close watch for fungus gnats.  For some interesting control methods, google "fungus gnats kill".

I like to start fertilizing with dilute soluble fertilizer as soon as a good stand of seedlings is up.  Make sure to water the fertilizer into the mix thoroughly with a gentle spray of water.  If you don't fertilize, the plants will grow very slowly.

For a very detailed description of growing Haberlea and Ramonda using this method, see here:  
http://www.srgc.net/forum/index.php?topic=71.msg722#msg722
See also http://nargs.org/images/stories/plants/Gentianopsis.pdf  and
http://nargs.org/nargswiki/tiki-index.php?page=Physoplexis-Phyteuma

SW Washington state, 600 ft. altitude

Peter George
Title: Member
Joined: 2009-09-03

How does one sterilize peat moss? I'm serious.

Peter George, Petersham, MA (north central MA, close to the NH/VT borders), zones 5b and 6 around the property.

Jeddeloh
Title: Member
Joined: 2010-05-02

I sterilize peat pellets for fern spore sowing by putting them in a heat proof plastic container (like a plastic shoebox), pouring boiling water in, and slapping the lid on.  The steam seems to do a good job of sterilizing it.  When it's cool I peel back the plastic mesh and sow my spores. I imagine you could just pack moist peat moss into any heat proof container  and nuke it for several minutes until it's good and steamy.

I think it might work to sow rhododendron seeds onto peat pellets the same way.  When I pour the boiling water in I try to avoid pouring it directly onto the pellets since that can wash out the peat.

My favorite plastic boxes for this venture are the clear plastic accessory boxes from The Container Store.  They hold 9 pellets which is enough for me of anything.

Good luck.

Jan

Jan Jeddeloh, Portland, Oregon, USA, Zone 8.  Rainy winters (40 inches or 1 meter) and pleasant dry summers which don't start until July most years!

RickR
Title: Moderator
Joined: 2009-09-21

Using boiling water pasteurizes, and has always been my choice if I need to do it.

But in view of your "I'm serious" comment, the medium's temperature must be raised above the boiling point to be considered sterile.  Using a pressure cooker, or in an oven in a covered but not sealed pan would be good methods.  :)

Rick Rodich    zone 4a.    Annual precipitation ~24 inches
near Minneapolis, Minnesota, USA

externmed
Title: Guest
Joined: 2010-03-01

Just to make things a bit complicated: I had 2 identical  pots of Rhododendron maximum (supposedly from the one red (chimeric?) plant still lingering in the Appalachian Mountains.  One pot I placed under a bright fluorescent plant light at 67F, the other I temporarily forgot in an unlighted 62F room.  Got rapid complete germination in the unlighted pot and slower 20% germination in the warmer bright light plant.  Transferred the lighted plant to the unlighted room and got, eventually, good germination.
These were special fluorescents that are two are 3 times brighter and also warmer than standard bulbs.  I don't know if standard 40 watt 4 foot fluorescents would have seemingly yielded poorer germination as well.
Charles S  MA USA
(one seedling has reddish stems-so far) 

NE Massachusetts (New England) USA  zone 6 (5B to 6B)

gardens visited, photographs:  www.flickr.com/photos/wildmeadow

RickR
Title: Moderator
Joined: 2009-09-21

That's interesting and useful.

My thermometer, placed 6 inches under the lights with the plants reads about 5 degrees F warmer than not under the lights.

67F is which?

Rick Rodich    zone 4a.    Annual precipitation ~24 inches
near Minneapolis, Minnesota, USA

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