Which plants are you hearing that about? I've never heard that before, and everything I've planted that's drought tolerant is very well behaved. Particularly if you focus on plants that are native to your area you shouldn't have any problems at all.
The only thing I could see happening is there are probably some plants that are nice and well behaved when you keep them on the dry side, but if they get more water may become more aggressive. However, many drought tolerant plants will die instead if you give them too much water, so I think the ones that become aggressive when well-watered are probably in the minority.
I'll get back to you on that. I am researching a long list and I can't think of which ones they are now. So you are saying, as long as I follow the optimum growing instructions, they should be happy where they are?
In most cases I would think so--there may be a few out there that are not native to your area and could be problems for you, I'm sure Utah has an invasive species list somewhere on the internet, so just look that up and doublecheck that your plants aren't on their invasive list. You can also look them up in Plant Files and look for negative comments (but if you do this, make sure you look for negatives coming from climates that are similar to yours...something that is invasive in Florida may not even survive in Utah, let alone be a problem) You can also post your list here, if there's anything that's got a bad reputation someone will probably recognize it and let you know (again though, pay attention to the climate they're from when people say a certain plant is a problem)
Yea, the invasive species list for Utah, is mostly weeds. Like crabgrass or chick weed. Nothing that I really even would consider. I look for that too. I look at the comments about plants and notice the area they are in or grew it in. Then I pretty much have an idea. Thanks ecrane!
In my opinion, there are a few popular non-native Xeriscape plants that could turn invasive like Russian Olives did (at least here in Colorado). I would keep an eye on Ravenna grass, "Blue Mist Spirea", and Russian Sage - again, my opinion.
Some plants are invasive when the growing conditions are optimum, and not invasive when the conditions are somewhat less than optimum. The Russian Olive is invasive here because it feels right at home.
Invasive has to do with plant growth habits, or perhaps "manners," and how it competes with the existing flora. Figuring out what is invasive is a process. We seem to be in a period of expansion of our xeric plant collection and finding out what works and doesn't work. It seems pretty rare to see an organization get the funding and time to really test the habits of any plants before they are sold to the public. That and the sellers frequently are ignorant of the plant past the information printed on the tag. It has pretty, purple flowers and likes full sun ...
The characteristics that make for an invasive plant can also be very positive ones. Requires little care - both water and nutrients, spreads quickly, disease resistant, etc. Bermuda grass is like that. It makes a great turf in hot, dry climates. Just try to get rid of it though.
Yeah, I would have said something potentially undesirably invasive should be kept away from "optimal conditions". Sometimes those statewide lists need to be used with some thought - a species might be fine out in dry grassland, but if it ever got near a creek, would go nuts, for example.
Some of it might be that distinction between invasive (well-adapted) natives and non-natives. A native plant well-adapted to dry conditions may be very difficult to eradicate, because it is perfectly capable of hunkering down hidden and dormant, or because seeds may wait two or three years to germinate, wherever they happen to have ended up at after all that time. But this behaviour isn't a problem, it's exactly the way that species fits into its native ecosystem.
Also, sometimes there are lists of plants that are invasive from the perspective of someone growing row crops. The plant in that region isn't a problem, only if it's growing where you decided you'd rather grow beans or sorghum.
I consider a plant invasive when it does not allow for any other plant to thrive and play nicely with others. In a desert not much is invasive but definite weeds and grasses like crab grass, we welcome most other trouble makers that can be bent into submission.
An effective ground-cover needs to be aggressive to fill in, compete with weeds, &/or provide erosion control. That usually means it would not work well in a flower bed or rock garden. All "short plants" are not equally adapted to be used in a rock garden AND as a ground cover. Right plant, right place, etc.