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:
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.