My stratification method this year

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My stratification method this year

Postby jbergeson » Mon Nov 13, 2017 2:22 pm

Last year I went crazy with bleach and zerotol pre-soaks, as I documented here on the forum.

I concluded that I did way more harm than good.

The year before that I had poor luck doing a warm stratification after sowing in seedling flats.

Opinions seem to differ on warm stratification and mold growth. Don and Larry recommend skipping the warm strat because of increased mold growth, while David Z seems to think the warm stratification helps give more uniform germination. I have communicated with another successful breeder who gives a several month warm stratification in moist Perlite and loves the mold - s/he says it helps break down the pericarp or whatever.

My initial impression last year was that mold growth had little detrimental effect.

This year I bought a bunch of empty tea-bags made of heat-sealable nylon mesh. I put the seeds of each cross into a teabag with a waterproof label and sealed them. I got the seeds wet with a soak (from a few hours to overnight plus) and placed the tea bags in plastic containers surrounded by moist Perlite. A few batches of seed had too many seeds to fit in a teabag so I mixed them with some Perlite and kept them in Ziplocs. Now I plan to give everything about 1 month at room temperature before putting them into the cold stratification.

My rationale for the teabag thing was as follows. Last year I just moistened the seeds and put them in the bag without any medium for moisture. I feel like some of them got too dry, especially if there were just a few seeds in the ziploc. I didn't want to just add some vermiculite to the bags because I couldn't handle the thought of trying to pick out six seeds from a bag of vermiculite or perlite in order to sow them. The other thought is that the teabag technique will allow me to give all the seeds a good leaching en masse between the warm and cold stratifications. I will let water trickle over them overnight or something like that. Can't hurt. It wouldn't have been practical to leach 200+ crosses individually if they were in ziplocs.

The Perlite I picked up at Lowes was Miracle-Gro brand and when I read the fine print there is some fertilizer incorporated into it. Heck, maybe that will help.

I wonder about the pH of the water and medium used for stratification. Would it make a difference? Some people use peat moss, which is acidic. Perlite, I believe, has a higher pH as does my water.

We'll see. Anyways I'm happy that I haven't killed most of my seeds by soaking them in straight bleach this year.
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Re: My stratification method this year

Postby Paul G. Olsen » Mon Nov 13, 2017 4:30 pm

Rose seed germination for cold hardy (Zone 2 - 3) species and rose cultivars in three easy steps.

1. Sow seed in small containers of soil or a soilless potting mix. Keep moist and at room temperature until February (minimum two months warm temperature).
2. Place containers in fridge or cold storage (temperature above freezing - no more than 4 C/ 40 F) for 3 months.
3. Remove containers and place outdoors in May (alternating warm and cold temperatures just above freezing in early spring increases germination) and seed will begin to germinate (some may already have).

This method, although it takes up more space, maximizes the survival of newly germinated seeds because there is no hand transplanting.
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Re: My stratification method this year

Postby rodrigomendes » Wed Nov 15, 2017 4:06 pm

I've been having trouble with stratification too. This year I used vermiculite in ferrero rocher boxes, I even use EM-1 as I see in a paper. But the black mold was the winner in the end, kill the most of my seeds. I keep doing embryo extraction for don't being frustrated. Onde day I will find my way!
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Re: My stratification method this year

Postby hoy127 » Thu Nov 16, 2017 10:39 pm

I used what I think was Paul's recommendation for germinating Spin. seeds - warm stratification followed by extended cold stratification (almost a year) and I now have Spin seedlings germinating! Carnea Plena, Mary Q of S, Doorenbos Selection, Madeline's Choice. Pictured is my one and only previously germinated Spin seedling (out of Doorenbos Selection)
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