Re: Seed germination investigation

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First, I checked all the bags to see if they still have seeds in them.  I sow all large seeds in small ziplock bags filled with a damp soilless mix. The iris are kept in a frost-free (but just barely) greenhouse so they experience  temperatures which generally range from 5 C to 25 C.  (about 40 to 70ish F).  As soon as I see a radicle emerge, I plant all the contents of the bag into a pot.  Therefore, if I still have the filled bag, it means not even one seed has germinated.

I dumped out each bag and felt my way through the compost to find the seeds. Quite a few had none left, but sometimes there would be empty skins, like the foetidissima Golden Gobbet seeds.  So,  three packets of gracilipes, two of koreana, one wattii and one odaesanensis, all from the 2004 list, had not been viable seeds and had disappeared.

Some seeds can remain, ungerminated, but still looking good, for several years.

Here are some numbers of remaining good seeds in my ungerminated lots from 2001:

 japonica pallescens (2 seeds remain from the original 9)

'Starting Versilaev' (4 seeds from 5 original)

tetra-sib x laevigata (2 seeds from 4)

unguicularis (2 from 15)

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I thought perhaps the seeds arrived late some years and that was the cause of a lack of germination success.  I was surprised to find out this was not true.

My first seeds were the excess ones - I bought 12 packets from the 2000 list and sowed them when they arrived, in August.  Every packet germinated, including two packets of lactea which I have not succeeded in germinating again. (I bought more lactea from the 2001 and 2002 lists). One lactea took only 3 weeks to germinate, and the other packet took 14 weeks.

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I would expect to get better at germinating iris.  Not so.

 My rate of germination has a downward trend, except for 2001 when I  was most adventuresome:  I bought lots of packets of interspecies hybrids and only a few  of them germinated.  Despite that, the rate of germination from that list was better than the 2004 one.

2000: 12/12 germinated  100%

2001: 10/23   43%

2002: 7/9       78%

2003: 6/8       75%

2004: 7/24      29%

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So, what happened in 2004?  Sunspots, poor pollination resulting in non-viable seeds?  The seeds all looked good - I always make a note if they don't. Did others have poor success then, too?

Next investigation:  did all my 2004 seed choices come from the same area?

 

Diane Whitehead

Victoria, British Columbia, Canada