Hello everyone,
Here in the southwest of France, early April marks the beginning of rose season, and some of my roses are already blooming. For once-blooming varieties, the pollination period is straightforward. However, for repeat-flowering roses, I wonder when the best time to pollinate is.
Is it more effective during the first bloom of the season or during later flushes? Have you noticed any differences in seed production or quality between early and later pollinations?
Looking forward to your insights and experiences
Hi @Nicolas !
Although I have nowhere near as much experience as others here, I’m in a (very) warm climate, and I try to get started on pollinations as soon as the first blooms of the season appear. That way, no matter the outcome, I can try again later in the year.
Supposedly, there can be a benefit to warmer temperatures in helping roses accept poorly compatible pollen if you are making very wide crosses, but other than that, why not get started early to maximize the window you have for making crosses.
If you want more seeds, I would suggest pollinating several times over two or three days.
This guide was very helpful to me:
http://www.abrigon.com/Rose%20Hybridizing%20Presentation%20Final_files/frame.htm
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You might have better success if you keep in mind the conditions under which bees are generally most active. You may have flowers when it’s too chilly for them or too hot for them. Those produced in the range under which bees are most active are probably more likely to succeed. There are reasons why systems evolve together. My climate is a chilly coastal type. I have flowers when there are no bees and when pollinated, they tend to fail in greater numbers than those pollinated when temps are within the range the bees are active. From experience in the old hotter climate and from reports from friends who live in hotter desert areas, if it’s too hot for bees, it’s too hot to successfully pollinate blooms.
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I haven’t noticed a big difference in seed quantity or quality due strictly to timing in my climate. Wet weather seems to be one of the most important limiting factors when it comes to affecting pollination and healthy hip set. Here, the occurrence of wet or dry stretches is fairly random and varies from year to year, and only the short-term forecast is reliable. I only collect anthers in the evening or morning before it gets hot, and then dry them indoors where there is air conditioning, so heat tends not to be an issue for me. High heat, especially if the atmosphere is dry, can reduce the amount of time that stigmas are receptive, so pollinating early in the day during that kind of weather is important.
It might also be worth considering that even repeat-blooming roses tend to produce more flowers in the early part of the season, so if you need to maximize seed set because your preferred seed parents have low fertility or because you want large quantities of seeds, that may still be the best time to target them for pollination as long as you have enough pollen available.
For me, as long as I have pollen ready (either dried and frozen or freshly dried in the open), the best time is often simply whenever there isn’t going to be much rain for a couple of days. If the weather and stigmatic receptivity permits, I’ll try to pollinate the same bloom multiple times, especially in cases of very desirable crosses, low pollen quantities, or poor fertility.
Stefan
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As a beginner I’ve been very surprised by the discovery that timing is such a major factor at many stages of hybridising.
- my early season/once bloomers did not coincide with with flowering of other prospective parents
- likewise some flushes of the repeaters
- and, of course, the climbers were late (all my plants are in their 1st year)
- finding that earwigs had eaten stamens before I got to the buds
- dry weather curtailing viability
These are just some of the challenges at the pollinating stage.
Something mentioned in passsing (on a forum response here somewhere 
), was allowing enough time for hips to mature in ones climate. Without factoring in that allowing hips to develop instead of deadheading for a new crop of blooms may reduce opportunities, I would consider any chance for pollination a gift!
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