Hip temperature limitations

What has been your experience with a rose hip’s ability to tolerate high temperatures?

I’ve read that temperatures higher than 32C(90F) affect germination but last winter I germinated OP seeds from an outside rose in Arizona and have never had such good results. Surely this rose had been exposed to temperatures of 40C+.

WE regularly get over 100 F every summer but last year. Also lots of days over 90. Germination ranges 30 % or so. There is not doubt from the work of von Abrams that maturing at too low temps affect germ % very badly, at least in conventional HT breeding. I think if the hips stay on, they’re most likely OK. Sometimes drought makes them drop early, but usually even that doesn’t prevent maturation. We live in eastern KS.

Here in Palm Springs, CA I used to germinate all of my seed w/out chill.

It works well for many things but you’ll find germination is more consistent and easier to control with chilling.

Chilling is needed for some seed parents, especially hardy cultivars.

I still sow some things w/out chill or sow seed from more productive crosses both ways.

Some varieties will get hip burn. Sometimes this can later lead to rot since tissue is damaged. Its uncommon but I see about 1 fatty hip per year do it.

Doug, roses love heat (to a point!) It’s 102 here today. We get excellent germination from good seed parents.

Even though rose growth seems to slow in the heat (above about 95 degrees), central CA is prime for growing vigorous plants. In effect, there are two growing seasons each year - Spring, from late Feb to June and in the Fall, from late August to November. It’s amazing to see the growth on plants grown in the rose fields in Wasco.

Jim Sproul