Finally Blooming! A Memo for the Second Year of Rose Hybridization

Hello, this is sou.
Now that the kids have started their summer vacation and things have calmed down a bit, I've decided to write down a memo about my second year of rose hybridization😊

The hybridization itself took place during Golden Week in May.
In the first year, I used two miniature rose 'Santa Lucia' plants as parent stock, but in the second year, I tried to broaden my scope by using three plants: 'Santa Lucia', 'Pure', and 'Sherwood'.
I also increased the number of flowers to be hybridized, going from 3 stems (or 3 flowers?) per plant in the first year to 5–10 stems. Since many fruits fell off before the autumn harvest, I increased the number based on intuition as a countermeasure, but later, when I saw photos of the hybridization that Mr. Iriya does, he was hybridizing 40–50 stems per plant.
Maybe I could have been even greedier... (lol)

One week after pollination, you can tell if it was successful because the unsuccessful flowers will wither from the tip or break off.
Hybridization is a hassle, but attaching the labels is tedious in a subtle way, so it feels a bit disappointing to think that effort went to waste. It can't be helped, though.
By the way, I buy the labels on Amazon. Including shipping, it's about 5 yen per label for a pack of 500. They are water-resistant and can be used until winter with almost no damage, so they are convenient.

I write the parent names with a regular permanent marker, and perhaps because these labels are excellent, they lasted until autumn without fading. If you want to save money, people use masking tape, but the worst thing is for the labels to rot or fade so you can no longer tell which variety was hybridized, so I don't think this is a place to skimp.

After about a month, I feel like I can tell whether the fruit has entered a stable period.

Stable fruits have a firm shape and will last until autumn unless there is a major accident. If they are not good, they will wither and turn brown from the tip.

The shape of the fruit seems to differ depending on the variety; Santa Lucia was bowl-shaped, Pure was perfectly round, and Sherwood was slightly elongated.

Management after the fruit stabilizes is simple: I remove new shoots and buds with soft pinching so that nutrients are concentrated in the fruit, and I try to maintain healthy leaves.
I was conscious of applying pesticides just like with other roses, and treating the buds the same way as growing new seedlings.

I wasn't used to soft pinching new shoots, but I think it means preventing the plant from creating strangely vigorous branches.

What troubled me during management was spider mites. They broke out in large numbers, and I panicked when spider webs started getting tangled even in the fruits. Anyway, since the plant cannot photosynthesize if it drops its leaves, I patiently exterminated the spider mites with showers and pesticide spraying.

Also, I was careful about watering during the summer. I think the basic rule for roses is to water thoroughly after the soil dries out, but I was afraid that the fruit would be wiped out by water shortage, so I set up a larger number of automatic watering timer sprinklers.
I made sure that plenty of water was supplied even if the soil wasn't completely dry.

And then November arrived. As the temperature dropped, the fruits colored up all at once, and the branches at the base of the fruits naturally started to become brittle, so I harvested them before they fell to the ground. There are 9 fruits in the photo, but there was one more misshapen one off-screen, for a total harvest of 10 fruits.

I put these in paper envelopes as they are and let them sleep in the vegetable compartment of the refrigerator until after the new year. This is to make them feel the winter cold early.

And then after the new year, I sowed the seeds in a cell tray.
There are various sizes of cell trays, but I used one with 7x15 rows. I decided on this size by intuition, but after using it once, I don't know if it was the right choice...💦←

The soil I used was 'soil for cuttings and seed sowing' sold at a home improvement store and 'top dressing for lawns'. I had some left over, so I used two types to use them up, but there wasn't really any difference in which was better. As long as it is fertilizer-free and the grains are fine, anything seems to be fine.

I made holes about 1cm deep with a dowel and sowed one seed at a time. I counted them just now looking at this photo, and it seems I sowed a total of 299 seeds from the 10 fruits.

When sowing the seeds, I peel the fruit, remove the seeds, and use a colander to wash away the germination-inhibiting substances around them. I did not perform any special soaking.

By the way, if anyone is interested in the procedure for sowing seeds, I think the video below will be helpful.
(※This video is from the first year of breeding)

After sowing, I kept the cell trays in a simple greenhouse to protect them.
I felt it wouldn't be good if the soil froze due to cold winds or frost.

The soil rarely dried out, but I watered them occasionally, and in early March, the buds finally appeared. The first cotyledons are round and cute, aren't they?

Due to space constraints at home, I set up the greenhouse under a cycle port, so it doesn't get much sunlight. Even in winter, the inside of the greenhouse gets quite warm when the sun hits it, so I think if I could have gained more heat, the buds might have appeared a little earlier.
And once they grow to a certain size in the cell trays, it's time to pot them up. From this point on, I switched the soil to potting mix for roses.

I am using 3-inch Presstera pots. I chose these because they are slit-type for good drainage, and since they are plastic, they can likely be used for many years if disinfected with benzalkonium chloride.

By the way, counting them in the photo above, there are 136 seedlings in total. Since I sowed 299 seeds, the germination rate is 45.5%. According to Mr. Kimura, a germination rate of 20-30% is considered a passing grade, so I think this is a great number. Hehe (lol)←

And so, after a while, they finally bloomed.
From around mid-June, small flowers started to bloom here and there. Since the seedlings are small, the flowers are also small, but each flower has a completely different expression, and they are quite unique.

Not only do children from different parents look different, but even from the same pair of parents, completely different flowers bloom.

This is it, really; when the flowers bloom, it's quite joyful and interesting (lol).
This is the real thrill of breeding and sowing seeds, which takes such a long time.

It seems common in the world of breeding to keep selecting at this stage, but for now, I will put labels on the seedlings with flowers I like and try to grow them as large as possible unless they die naturally.
After all, it's hard to discard them after seeing just one flower... Since my home space is limited, I think I won't be able to say things like this eventually, but for now, I want to pour equal love into all of them.

That concludes the summary of the second year of rose breeding.
Please give it a try yourself!
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Thank you for watching until the end.
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