Rooting Euphorbia Ammak Going Into Winter?

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pone
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Joined: Fri Nov 22, 2019 8:25 am
Location: Zone 9a San Francisco Bay Area

Rooting Euphorbia Ammak Going Into Winter?

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A local succulent grower had a 20 foot Euphorbia Ammak that they sadly had to cut down. He cut it into pieces to sell off. I bought two of these, each about three feet long cuttings. Unfortunately, I had been lead to believe they were already rooted, and when I pulled them out to repot they had no roots at all. This puts me in a difficult situation because we are heading into Winter. How do I maximize the chances of these cutting surviving the Winter and perhaps even starting the rooting process before Spring?

Some background: I am in zone 9a. It would be a rare year when we have more than one or two days just at freezing, but days below 40F are fairly common. I have no room inside the home for a large euphorbia. I have no greenhouse. I have extremely limited patio space that is sheltered outside from the rain.

I have some experience growing euphorbias outside in the Winter, in containers. They are clearly very difficult plants to grow outside in zone 9a, but I have learned a few things along the way. I started out using a gritty mix that is about 30% sized bark and 35% each of sized turface and stone. The euphorbias that are most susceptible to rot simply cannot handle Winter rains in that soil. I then started to substitute pure 1/8th-inch pumice as the only soil component for most of my outdoor cactus and euphorbias, and remarkably enough most of them survive winters in that mix. I have more or less concluded it is nearly impossible to overwater a plant in pure pumice because the water adhesion to 1/8th pumice is just not great enough to promote rotting conditions. But so far my experiments doing this have all been with rooted plants. I have never tried to leave an unrooted cutting out in the Winter rain and I am concerned about doing that without hearing more from others here.

Strangely enough, sometimes sheltering a new cactus from the sun exposes it to new risks. I had two nice Cereus Peruvianus Monstrose cuttings that I put into pumice, then I put them into a sheltered porch area. That protected them from Winter rain, but unfortunately, the scale bugs thought that was a great idea too and infected both plants. One of the cactus ended up developing a rot right in the top section where some of the scale bugs had concentrated, and I had to cut off the top to save the plant. The top ended up being totally lost to that rot. I took those infected plants out into the full sun and within a few months, every single scale bug was gone. No insecticide applied. No neem oil. Nothing. Sun alone cured the problem by making the cactus surface simply too hot for the bugs to be comfortable. So the lesson there is sheltering plants can be as dangerous as exposing them to the elements, and there are probably no risk-free environments.

In any case, I understand that I am taking on a lot of risks exposing these plants to rain, but I feel if I can make these plants survive those harsh conditions I will have learned a lot about soil characteristics and weaknesses of each species.

Hopefully someone can help me understand the best approach to take with my large Ammak cuttings.
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