RE: HYB: Daylight Independent

I do wonder if what you are seeing with Romantic Evening is delayed bloom. You may wish to check the rhizomes in spring, perhaps some digital pics, and then see what reblooms later. This would be useful information. The reblooming seedlings would suggest some genetics are there. The lack of consistence would suggest to me tht perhaps it is not the same as other reblooming biology. 

To get a good rebloomer we need several factors.
1) extra vigour , particularly so plant can still survive after blooming rhizomes are killed by frost. This means no so much hardiness as lots of increase. 2) Shorter maturity time for rhizomes. This means that an increase can mature to bloom size faster then average. 3) Doesn't need winter estivation to set incipient bloom stalk. Could possibly set bloom stalk with cool evenings or not even need estivation 4)Early spring bloom may be an additional factor or a reflection of item #2, that is earlier maturity or faster growth. 5) Smaller trigger size for rhizome. This is a term I use to indicate size of the rhizome needed to trigger a bloom stalk and support it. Some of the Schreiner's iris need to nave large rhizomes before they bloom and a number of them don't bloom in cooler climates as there just is not the time to produce size needed in the growing season available. The AB Walker Ross for instance can set up a bloom stalk on a rhizome that in only 1" in diameter. 
6) Lesser dependence on cool evenings to develop bloom stalks.
These are just some things off the top of my head. Others can add to this list.
Forever Blue seems to have all these factors plus it is daylight neutral, like the everbearing strawberries. You have repeat raspberries and strawberries, that produce two crops a year and the Daylight Neural strawberries that produce a small crop but continuously throughout the year. Most rebloomers are like the fall bearing Raspberries, and have two seasons. Sometimes these seasons can come early, but still two seasons.
I have kept soil temperature here for several years and can go back and look at t he data. I also have some rebloomers planted in an unheated greenhouse, and the temperature there is much higher then outside, getting over 40 C (105 F) on many days. Still, rebloom is better there and sooner then on the same plant outside. The plants in greenhouse do get a larger temperature differential between day and night temperatures. I have noted a correlation between ground temperatures and bloom time of Spuria Iris. 

Chuck Chapman

Date: Sun, 17 Feb 2008 20:21:51 -0800 (PST)
From: Robin Shadlow <rshadlow@yahoo.com>
Subject: Re: [iris] RE: HYB: Daylight Independent
I know that Romantic Evening rebloomed for the Jedlickas in western NE. Their peak is usually the first part of June, so the July rebloom report would be less than 60 days. I haven't counted the number of days, but have had 2 or 3 Romantic Evening seedlings bloom in the summer. But certainly Romantic Evening is an extremely sporadic rebloomer and unless it can be enhanced to become much more dependable, it may not be all that useful. I just may have to try some Forever Blue pollen on the Pink Attraction x Romantic Evening seedling that bloomed last July.
Mike Lockatell has mentioned to me that soil temperature is significant as well as cool nights to trigger rebloom. It would be interesting to see if we can determine a preferred soil temperature for the rebloomers which are daylight dependent.
What I really hope is that you did some sib crosses with your Forever Blue x Immortality seedlings Chuck. If we could get some seedlings that had both the daylight independent genetics from Forever Blue and Immortality's trigger, we could REALLY make it hard for the growers to have enough unbloomed rhizomes to fill orders : ) 

 Robin Shadlow
 zone 5 NE







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