I've recently become disillusioned with Cordyline fruticosa. I have five, at the moment, one of which has been with me for four and a half years now. But -- and it's a big but -- it's no longer the case that Cordyline is an "easy difficult" plant for me, as I said in the profile: I realized this around October or November this year, when I went to check them for watering and found spider mites on one. Again. Just like every other year I've had them. Previously, I've tried spraying the mites off with water, hand-washing the leaves with soap and water, spraying with neem,1 and anything else that's occurred to me, but it never gets rid of the mites: they're always back in a couple weeks. It's time-consuming and frustrating, but I felt obligated to do something, so I kept doing it.
And I would still have been okay letting the Cordylines stay where they were, mingling freely with the other plants, if not for the fact that they'd all started to get burnt tips and margins. The 'Kiwi' went first, in December 2009, and the others followed about six months later. My suspicion is that this was a delayed reaction to the change in water since we moved: in Iowa City, we had soft, slightly acid river water, and now we have hard (sometimes extremely hard), alkaline aquifer water. This is my theory mostly because I've ruled out pretty much all the other possibilities: the change in water is the only major thing that's happened to them.
So what I ultimately wound up doing with them last fall was: I watered the four small ones, sprayed them thoroughly with neem, put them in plastic bags, and stuck them in the basement. If they survive the winter, great: I'll cut them back, let them resprout, and send them outside for the summer. If they die, well, I was basically ready to throw them away already, so.
None of which is even the point of the post yet.2
The point of the post is that the one exception was the large solid-green plant, which I've had for about three and a half years. It didn't start getting tip and margin burn when all the others did, so I have decided not to bag it for the winter. It probably has mites, but I'm willing to live with that if it'll just hold on to its leaves and not share them with too many other plants.
So what's different about how the green one was treated, compared to the others?
The green one spent the summer outside last year. I think the explanation for the lack of leaf burn is that it got rainwater all summer long and hasn't been watered very often since I brought it in, so maybe doesn't have minerals built up in the pot to the same degree as the other Cordylines.
However, I am reminded that being outside for a summer is not entirely without its own set of problems:
That's a baby oak tree growing in the pot there. I suppose I should have known this was a possibility, since I've pulled dozens of maple seedlings out of every container I've had outside since we moved, but somehow it never occurred to me that oaks might be weedy too. I suppose technically one has to blame the squirrels.
In any case. The oak obviously can't stay there in the pot, and we're not in need of another oak tree, but I sort of feel like, you know, it's trying so hard. So I'm wondering: when and how would one go about transplanting it to the yard?
1 Not recommended -- they always dropped a bunch of leaves every time after I neemed them.
2 Though I've wanted to write a post about the giving up and bagging for quite a while, and am pleased that I've gotten to use that picture finally.