Stratification of seeds, prepping them for planting, planting

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mnemko
Posts: 67
Joined: Wed Feb 21, 2018 7:36 pm

Stratification of seeds, prepping them for planting, planting

Post: # 73517Post mnemko
Mon Nov 22, 2021 1:15 pm

Someone from India emailed me to say he's started to hybridize roses and asked me what to do with the hips. Here was my response. I'm curious if you agree with all this or would like to offer a suggested change:

The standard advice in the U.S at least is to try to simulate winter: Harvest seeds in late fall (November or December) (when the hips start to turn orange, or by mid December no matter what the hips’ color is. Store the hips in plastic baggies, one per cross—label the baggie with the cross’s name) in the fridge for 4 to 6 weeks.

Then, on a nice-weather day in December or January or perhaps February, take one baggie (that is, one cross) out of the fridge and use a knife to cut a ring around each hip—Don’t worry about cutting the seeds. They’re too hard to be cut with a knife.

Then, with your fingers, pull out the seeds and put all the seeds from that one cross in a small cup of water so they don’t dry out. They’re very sensitive to drying out.

When all the seeds from that cross have been removed and cleaned (remove any hip material from the seeds), rinse them in a tea strainer. Then put the strainer with the seeds in cup that contains a solution of 1 part Clorox bleach to 10 parts water for 10 seconds.

Repeat the process with each baggie (each cross.)

Then, immediately plant the seeds in a light soil mix. You can use a commercial one such as the one I use:


or make your own: https://www.gardenbetty.com/how-to-make ... tting-mix/

Germination rate varies with the cross and the climate but averages 10 to 35%. So put 2 to 3 seeds in a plastic “rose pot”: 2”-wide x 3” deep plastic pot.


Put the pots in a shaded location until they germinate. Cover them in clear plastic to keep them from drying out. Water whenever the top of the soil becomes lighter colored.

As soon as they germinate, move them into a part-day sun location and when they have 2 or 3 pairs of true leaves (not the first pair—those are false leaves) move them to a full-sun location.

By April or May or maybe June depending on your climate, you will have your first flush of blooms. Be ruthless and toss out any that have disease, an ugly flower, one with fewer than 10 petals, or weak plant growth. Every week or so, put a gold plastic toothpick next to very good ones, a silver toothpick next to good ones.


Your goal at the end of the season should be to have one to six roses you’d like to evaluate for another year.

Feel free to ask me other questions.
Marty Nemko
mnemko@comcast.net
510-655-2777

MidAtlas
Posts: 113
Joined: Mon Jan 28, 2013 8:49 pm

Re: Stratification of seeds, prepping them for planting, planting

Post: # 73520Post MidAtlas
Tue Nov 23, 2021 12:11 am

Following those instructions, stratification probably wouldn't actually start inside the hips under refrigeration unless the flesh begins to break down and provide moisture--the process requires a combination of chilly temperatures and moisture for an extended period. The achenes may instead be removed from the hips soon after harvest and then placed into a moist medium in the refrigerator in order to stratify. My medium of choice for this is usually a combination of peat moss and compost, but preferences and materials availability vary widely. Horticultural coconut coir might be a more widely available substrate. I generally allow the seeds to begin germinating in their clear baggies in the refrigerator, planting them individually as they sprout, but that is because I mostly work with small quantities. For larger numbers of seeds, it may make better sense to plant everything after a reasonable stratification period (say, a few months), as long as the temperatures where the seeds are planted are cool enough for germination. If high temperatures pose a problem for germination, depending on the local climate or time of year, then it may still be helpful to allow the seeds to sprout under refrigeration. Others do not do this next step, but just after their removal from the hips, I generally scratch the surface of the achenes to break their thin aril-like coating and then allow them to dry (anywhere from a few days to a few months), before eventually soaking in water for about 8 hours or overnight and then placing into the stratification medium. That seems to help improve my overall germination rates and reduce losses to mold without resorting to bleach or other disinfectants, and I can better control when I begin stratification--for me, I generally want to delay it so that I will not become overwhelmed with seedlings indoors during the winter.

Also, I would worry that it might not be completely safe to expose already-stratified achenes to dilute chlorine bleach, especially if they are not rinsed with water immediately afterward, for the same reason that drying stratified seeds could be harmful: the seeds inside may already have begun to lose their dormancy and germinate. Some people will do this before stratification, although I do not.

Stefan

mnemko
Posts: 67
Joined: Wed Feb 21, 2018 7:36 pm

Re: Stratification of seeds, prepping them for planting, planting

Post: # 73521Post mnemko
Tue Nov 23, 2021 2:23 am

All good thoughts. Perhaps because I live in the S.F. Bay Area, post-shelling stratification may not be so important. Re the bleach, I guess my assumption was that leaving the bleach residue from dipping the seeds in a weak solution for 10 seconds would help protect the hard seed coat without damaging the growing part within. Perhaps I'm wrong. My average germination rate has only been about 15%.
Marty Nemko
mnemko@comcast.net
510-655-2777

roseseek
Posts: 5297
Joined: Sun Dec 11, 2011 6:54 pm
Location: Zone 9b Central California, Sunset Zone 15

Re: Stratification of seeds, prepping them for planting, planting

Post: # 73522Post roseseek
Tue Nov 23, 2021 10:40 am

Have you considered that fungal and bacterial action may be required to assist in breaking down the seed coat? Perhaps being "too clean" is inhibiting your germination?
Kim
California Central Coast
USDA Zone 9b
Sunset Zone 15
Cooler inland coastal valley with strong marine influence

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