Stratification-Germination Question from Novice

I’ve dabbled in hybridizing roses (and various other things) since I was a teenager, but have learned so much since becoming a part of this forum a couple of years ago. Thanks to all of you!

I generally stratify my roses seeds in labeled zip-lock bags with a damp paper towel. I put them in as soon as I gather them in the fall, and then start checking for germination a little after the first of the year. I start potting them up individually as I see germination. Germination is now at a standstill. Would you suggest: 1. Removing them from stratification and keeping them (in bags with moisture) at room temperature while continuing to check often for germination. 2. Sowing the seed in flats outdoors or in the greenhouse now that spring has ‘sprung’ here Indiana.

I feel like with choice A I am eliminating wasted space with seeds that were not going to germinate anyway, but perhaps there is something that I am missing. Thanks again!

I don’t know if you are talking about HT crosses, or species crosses, or what class, nor do I understand if you are fluctuating temps (in and out of cooler)… And I should say I am probably at least as green at this as you are (having had virtually no hips to harvest for several years)! But my M.O. was to do about 2 months in cold, and thereafter several days out, a couple weeks back in the fridge, several days out, etc… The fluctuations seemed to stimulate additional germinations. Thereafter, for me, it is akin to deciding when to stop the microwave in which the popcorn is popping… If it has slowed down enough…

(…Either that, or I quit when I learn that, unbeknownst to me, a well-intentioned soul has decided to defrost the fridge I use – that was a definite terminating point, resulting in a flush of germinations getting frozen in the newly uber-efficient, ancient ice box… I’m over it though… Really… All is forgiven… No really… Hardly ever think about it anymore…)

Too funny!

Yes, Kim… I’m sure I too will look back on it one day… :wink:

I did lose a lot of interesting seedlings that year. I was shocked at how many proved viable – all those poor, petrified, icy strings of seedlings with their little faces frozen against the sides of the baggies… The image still haunts me. (Truthfully, I never could have grown so many of them on…)

BTW, I haven’t had much experience with species crosses, but those can take a year or so of the above treatment, as I understand it, particularly for northern species. I would imagine that you can get a rough idea as to how tedious stratification might be based on how cold-hardy, and how heavily dormant a parent species tends to be. I should let others with more experience chime in, however. I’m mostly speculating.

[attachment=0]Rose seedlings April 13 2015.jpg[/attachment]Theodosia, I am curious, how many germinations did you get while the seeds were in the refrigerator? I work with modern HTs and Floribundas, and I never had a single germination during the 45 degree stratification period.

Are you working with older/species roses or modern varieties? Germination rates varies by cultivar if you are planting the entire seed. In my breeding program, some cultivars have less than 5% germination, some almost 30%.

In my NJ location, I collect seeds in early fall, stratify for several months, then sow seeds in January. I sow the seeds of each cross into a 3 inch pot, maximum 10 seeds per pot. I keep my seed flats in a barn studio that ranges from 50 to 55 degrees F. When seedlings show true leaves I transplant them into individual pots and move them under lights.

Germination seems to have ended now, but I will keep the seed flats in the studio for another month or two, then toss them. It gets hot quickly in May so placing the flats outdoors will not work. I may try putting the flats into a fridge at this stage to stratify again. Then place back into the 55 degree studio for a month or two.

Central NJ, zone 7a
Rose seedlings April 13 2015.jpg

Cathy, I’m curious how you accomplish cold stratification prior to sowing. I think it has to be a moist stratification out of the hips.

So far this year I’m having some quite low germination percentages. I usually sow my seeds in November or early December and keep them in cold storage until March. This year I got late and sowed the bulk of my seeds in I think late December or early January and another batch of OP seeds on February 22nd. Some seeds from crosses done on Ann Endt, sown in the early seeding, came up quite thickly and quickly. An entire flat of OP Ann Endt from the later seeding didn’t have any germinations at all after two weeks out in the greenhouse. I would estimate that it had about five or six weeks of cold treatment, which in this case was clearly not enough. I have now put them back into cold storage.

What is really interesting this year is the dramatic effect the pollen parent seems to have upon germination speed and percentage. Of course there are always other unknown variables, such as pollination and hip collection dates, of which I have not kept track. I can’t remember all of the examples here at the computer, but in general Commander Gilette (Basye’s Legacy) pollen seems to really make seeds want to germinate, while the seeds with Petit Pink and Persian Yellow as pollen parent are vastly more reticent to germinate.

I really need a better database system to keep track of this, along with the discipline to actually enter events as they occur.

Jbergeson (what is your first name?) … In Sept and Oct I collect the hips, remove the seeds, soak the seeds in a diluted peroxide solution for a few hours then place them into “Baggies” without paper towels. So the stratification is not totally dry since the seeds are wet going into the bags. I check weekly for signs of mold. In January, after approx. 90 days at 45 degrees F, I sow the seeds. I do not want to fill my refrigerator with flats, so the Baggie approach saves space in the fridge.

Central NJ, zone 7a

Thank you so much for your responses! I so appreciate the wealth of knowledge this forum provides…amazing.

I generally clean my seeds as soon as I collect them in the fall and space them on damp paper towels. Then I roll the towel and seed and slip into a labeled zip-lock bag placing it on the bottom shelf of our refrigerator (my wife is so patient with me!). I start checking for germination about the first of the year, but it generally does not start until late February or March. One goal is to delay it as long as possible, because I don’t want to mess with a bunch of seedlings inside under lights. The hope is to have them germinating about the time my small greenhouse (mainly solar heated) is up and going. I check the seeds about every week, carefully pick out the ones that have started to germinate and put them in small pots for further growth and observation. This year the rate of germination, while in the refrigerator has gone from zero to almost 100 percent with one variety. Sadly, the one that is at 100 percent is from some unidentified hips that were actually here in a drawer. I collected them somewhere and, sadly, did not label them. Whatever they are, they germinate like weeds.

As to what I am working with, that is a good question. It is pretty eclectic, including species (arkansana, palustris), old garden roses (gallicas, rugosa), a few hybrid teas, some buck roses, and a few modern shrub types. I’ll be honest, most of my crosses are not done with any kind of scientific thinking other than, “I wonder…what would happen if…” My worst rose is actually a seedling from the first cross I ever made years ago. It is a sickly pink, very brittle branches, growing straight up like an exclamation point, dies to the ground every winter, BUT I just couldn’t bear to cull my first “baby.”

Theodosia, I recommend that you label your crosses when you make them. You can buy plastic labels with a hole that the label slips through, or use a “Sharpie” on pieces of a milk carton, tied with string or plastic ties to the stem where the hip is. Write the name of the seed rose first, then the name of the pollen rose. When you collect the hip and harvest the seeds, include the label in the zip-lock bag. Knowing what cross you made is an important step in evaluating the success of your hybridizing program, including the germination rates of different crosses.

I wish you the greatest of success!

Central NJ, zone 7a

Most roses will germinate in the cold, even 40 F, but it takes a couple months longer than if taken out at the exactly optimum cold stratification time. I believe that Semeniuk published that. Check my review. This past year I held most of my rose hips cold until mid-Nov, then shelled them out, put them with vermiculite and nitrate and stuck them back in the refrigerator. From some lots I have as much as 75 % germinated. Even with Rainbow K.O. I’ve hit over 70 % already with the peak in Feb/March. ON the other hand Rosa pomifera and R canina show almost no signs yet. It may be July before they emerge. The HTs and complicated mixtures take after their parents. Last year I had from 0 to 80 % with a median of 42 % germ in 1 yr at 40 F. I gave up after that long, for practical reasons.

“I recommend that you label your crosses when you make them. You can buy plastic labels with a hole that the label slips through, or use a “Sharpie” on pieces of a milk carton, tied with string or plastic ties to the stem where the hip is. Write the name of the seed rose first, then the name of the pollen rose,” Cathy

I started using sharpies on plastic labels, but found that some of them faded completely out before harvest (This was actually on some hemerocallis crosses). Since then, I have been cutting small metal tags from recycled aluminum cans. I “etch” them with a pencil or nail and use a paper punch to put a hole in one end. I use the same kind of tag for the roses once they germinate, and in the trial area of my garden. What I am not doing as carefully as I should is keeping records of results from particular crosses. The seed that has had nearly 100 percent generation was not from a cross, though. I often pick up open-pollinated hips while walking (asking permission if it is not on public property). That was the case with these. I stuck them in my pocket, and then into a drawer, where they were forgotten for a long time. After several months of stratification, they came up like radish seeds!

“This past year I held most of my rose hips cold until mid-Nov, then shelled them out, put them with vermiculite and nitrate and stuck them back in the refrigerator.” Larry

I’ve never tried the nitrate, but could so next time, because I have some I use for germinating difficult capsicum species. I think it is interesting that the pollen parent can influence germination too.

Once again, thanks to all!

Unfortunately, there is no such thing as a “permanent ink marker”, not even Sharpies. They simply wash off or fade with UV and the other elements. #2 pencil on a non smooth plastic label will remain legible seemingly forever. I have to erase them when reusing labels, sometimes with some dirt added to the eraser to completely eliminate what had previously been written on the tag. Etched or embossed metal labels are also extremely durable, but where direct sun and heat are extreme, anything metal tied around a cane, even very loosely, appears to eventually damage it. As long as some critter doesn’t remove the tag from the pot, which I’ve known some dogs to do and desert rats in the old Newhall garden did with regularity, pencil on a non-smooth plastic label will keep the plant identified for many, many years.

There are “paint” pens that look like “ink” pens, but they do last for many seasons. They are normally available at craft stores. Apparently they are available as both oil and water based. I use(d) the oil based ones.

As a general rule, dyes will fade, and pigments tend to be more durable (though some “pigments” are actually dyed particulates.) Graphite is a pigment, and a pencil is always easy to write with, though, as Kim says, plastic tags can break or be removed by critters. For more permanent plant labels, I cut aluminum tins (from store-bought pies or rolls) into strips, emboss them too, and tie them to a stem.

Always a good idea to at least keep your hips in a labeled envelope, IMO. Just save the blasted SASE from all the credit card offers and solicitations, and you’ve got a heckuva supply of free envelopes…