Well, this is quite annoying!

Pollination time here in Tucson is from about March 25-May 5. After that it gets too hot for the pollen to take.

We’ve had a very cold winter here (for Tucson) but now I’ve got a sea of buds popping up all over the rose garden. Problem is, the weather went from a high of 70 to 95 in one shot! If it stays this way, there will be no pollination season at all this year. And my poor little seedlings are suffering as well. Bummer! What’s a poor hybridizer to do? :frowning:

Well, looks like the heat will break this week. Just in time!

It’s been wacky weather all over. This winter in CA was quite special. The temperatures were fluctuating from unusually high to unusually low, and nothing knew whether it was supposed to bud or bloom yet, so things would keep trying to bud out and getting frost nipped.

I’ve got the same problem here Judy. It was over 100 yesterday. I am getting out early and hybridizing as much as I can. I have no other choice. I’ve got my fingers crossed.

Would temporarily placing shade cloth above the seed parent help with summer seed set. I’m thinking 4 rebar poles with shade cloth draped between them over the plant for 24 hours before to 24-48 hours after pollination. I don’t know if it would work at all as I’m still new to all this.

Robert and Judy, Sorry to hear about your poor pollinating conditions. Any chance that doing your pollinations in the evening would help? I guess there is one advantange of living in a northerly climate, the pollination window may be tight, but we would never see those sorts of temperatures in May or June. Good luck, Liz

Polyamines are supposed to help pollen germinate at high temperatures, see for example:


See also:


In the past I have thought of doing an experiment in which I add the epoxy polyamine component (in 2 component epoxy glues or paints, see:epoxy polyamine - Google Search ) to pollinations in hot weather, but I have never gotten around to actually doing it.

Does anyone know of a commercial source of a polyamine known to work with pollination?

Link: pcp.oxfordjournals.org/cgi/content/abstract/43/6/619

Temps are supposed to be moderating. First thing in the morning the conditions are near ideal. I already see hips swelling. Thanks

The article cited above says that the essential polyamine is spermidine. That is nothing like what is in epoxy. Other polyamines commonly made in human and animal bodies seem to not be effective accroding to the article abstract. I know that Sigma-Aldrich Chemical Co sells the stuff. I would have to check into prices from their catalog. It might also be available from a place that does things like plant tissue culture materials.

The oxfordjournals abstract states: “High-temperature inhibition of pollen germination was alleviated by the addition of spermidine or spermine but not of putrescine to the germination medium.”

The molecular structure of spermidine is given at:

Please compare the structure of spermidine as given above with the epoxy amine additive DETA ( diethylenetriamine ), see:

Of course it may not work, but I feel that they are close enough so that someone should try.

Link: en.wikipedia.org/wiki/Diethylene_triamine

What is the acceptable temperature range to accomodate ideal pollination??


I don’t think I’ve ever heard an “official” range…and I would imagine that local climate conditions play a significant role in determining a temperature range as well (humid vs. arid). However, from my own personal observations for southeast PA, I would say I am good until temps start going above 90-95. At that point I tend to start having problems with some of my seed parents (pollen production is still good though). I believe I get my best results right around 75-85 degrees. Humidity here in the spring is usually somewhere between 50%-75%.