Although I live in temperate SF, I think I can answer most of your questions.

I've grown membranacea for several years in the ground in my SF garden, and I've also grown them at Strybing, and during that time we've had a few temperature extremes. Two years ago my plant went through three nights of about 28F with no problem other than a few dropped leaves. It also seems to hold up OK with our occasional 90F day. Mine gets about 3/4 day of sun, which is probably near the maximum it likes. Mine blooms profusely every year, about 10' or more up the vine. It also has a lot of fruit, but usually no seed.

I'm very doubtful if one would bloom in a 1-gal pot, or even a 2 or 3 gal pot. This is a very large and vigorous vine which does best in the ground. From your picture it looks like it could use a bigger pot already.

I've had fairly good luck rooting cuttings in perlite/peat with bottom heat and mist, although it is a little slow rooting and sometimes a bit difficult.

Hi daveh,

Thanks for answering my questions so quickly and so completely.

It sounds like our "normal" winter cold should not be a problem. Those less frequent years when it gets closer to 25 F may require more care, but if it's in pot that in theory simplifies things.

I'm curious if you know how hot it got at Strybing or where you live last summer? For those not in the area, I assume last summer had one of the largest number of very hot days. SF got in the upper 90s (100 in some spots?) a couple times, but as always this varied a lot depending on location. I was briefly at Strybing 2 days after the hottest one, and all the plants looked like nothing had happened (although I wasn't looking for damage).

Another question I have for anyone is what is the climate like at the UC Botanical Garden in Berkeley? Can I assume it gets hotter than it does in the flat areas closer to the Bay?

For those not from the area, discussions of temperature variations among all these areas may sound a bit silly. We are not that far away and not separated by mountains or anything like that--mainly proximity to the Bay and/or Pacific. Down in the South Bay we are warmer than SF and Berkeley (during the day, but not night) in Summer. However, we are definitely not hot like parts of Northern California (Sacramento), the warmer parts of the East Bay (Livermore) or the valleys of L.A. county for that matter (Pasadena, SF Valley). We do think SF is awfully cold, though.

In case anyone is curious, a comparison of Berkeley and San Jose average temperatures:

http://www.wrcc.dri.edu/cgi-bin/cliMAIN.pl?ca0693
http://www.wrcc.dri.edu/cgi-bin/cliMAIN.pl?ca7821

Often a plant that thrives in the cooler summer areas will do just fine if given afternoon shade down here. Most things benefit from our cool nights.

daveh, it sounds like afternoon shade, at least in the summer, would be wise here. I will repot soon, before things warm up. I was going to try 3 gallons. Is there any particular reason not to move straight up to 5 gallons? I was surprised to read the Passiflora book claim of it blooming in an 8 inch pot, and I had actually told my friends that I was under the impression it required planting in the ground. So hopefully 5 gallons (or maybe eventually 10 gallons) will do the trick. The fact that its leaves are very cool is a big plus in light of its eventual large size.

I remembered that Annie's Annuals and Perennials also sells the plant (you need to get on their list to be notified when it is available). $25 last year. They had also said that constraining the roots stimulates fruit production (I wonder if they meant flower). Annie's grows their stuff outside but they are 10 miles from Berkeley and share their climate.

It sounds like I will eventually have a lot of material for cuttings--great to hear it's not impossible.

I don't remember exactly, but I think it got up to the mid-90s last year in SF where I live and also at Strybing. It gets several degrees hotter and drier at UCB Botanical Garden than at Strybing. You're right, I would definitely give membranacea some shade in San Jose.

You should be able to repot straight to 5 gal with no problem.

Mine took many days of low 90's with no problem, but it did not have late afternoon sun....but was killed outright at 27 degrees this winter....it was, however, a yearling plant.

We are experiencing a bit of a heat wave in California. It's not just that it's hot, but that it's only April and I don't think plants have adjusted. High temps: Sunday 91, Monday 95, today looks like it's headed towards the mid 90s again (88 at noon).

My P. membranacea got sunburned on several leaves--my fault since it was getting afternoon sun. What a find strange is that it's growing like crazy--not only existing growth, but it's putting out all sorts of new growth--it looks like not only does it tolerate this weather, but it loves it. We have had some huge day/night temperature difference--as much as 40 F. Perhaps this plays a role.

I think I'll start a thread on peoples' experience in California with this heat wave and their cool growing species. This is really unprecedented heat, breaking a lot of records by several degrees. SF was 93, old record 87 if I remember correctly.

When it was 95 yesterday the humidity was 17%.