cloudy christine, The siding I have been using is @ 9" tall by however long I can find. That means the trench has to be @ 9 1/2 inches deep, by 4', 6', 8' long, so that the top edge of the siding is just below the dirt surface. The siding is laid in the trench horizontally. You don't want it below the surface too much, otherwise roots will find their way over the top and back into your yard. The "ends" are overlapped as you continue on with the trench. Today I was adjusting some patio block that I have under my chain link fence (which makes grass trimming so much easier and also keeps animals from digging to get under the fence). I had to laugh, because I put the siding (root barrier) along the fence over a year ago, so as I took the block out to fix the dirt under the block, there was the root barrier with all the forsythia roots bunched up on the other side. They couldn't get thru. It made such a difference in my raspberry patch last year, not having the neighbors forsythia roots sucking up all the nutrients. It is a lot of work, but well worth the effort. You have to do a little at a time, and it will eventually get done! I don't know of any other way to stop the roots. I did the same thing on the other side of my yard where I have my tomato garden. The other neighbor has a huge pine tree about 4 feet from my fence. You know how it is, everyone has to plant their trees along the property line, forgetting that they will grow up some day! Every year when I till the garden, what do I find? Yep, pine tree roots. I put the siding root barrier in that area and now I don't get any roots in the garden. Paul

I've never heard of anyone describing epimediums as "invasive" or even very aggressively spreading - they tend to be colonizers, forming slowly expanding clumps over a period of time. In fact, I'd say many would consider their growth and spread not to be fast enough :-) The easiest way to control spread is to sever any rhizomes that stray too far away from the mother plant with a sharp spade and remove and replant elsewhere (or give to fellow gardeners). The edging could also work but would not be MY first choice from a purely aesthetic standpoint.

Thanks for this suggestion! I hope you will answer a few more questions. The picture is a worse than I originally described. The very agressive invading roots are between 4" and 12" deep (I find large roots deeper than that but they don't appear 'agressive.') In the Texas clay, the hole I prepare for my roses must represent an oasis. The invading roots multiply as if in a Sci-Fi movie! Before reading the pot suggestion, I became so frustrated that I took a 3 gallon plastic pot from the nursery (it was for a regular size rose), cut its bottom off and stuck that into the hole I had dug for my mini rose. I planted my mini in that, not knowing if this was a good option. I removed the bottom of the pot for drainage, but invasive roots will eventually come in from this opening. Would a stronger pot be better? How about a terra cotta pot? What about the bottom of the pot? What size pod do you use? Do you leave the rim above or flush with the ground surface or do you submerge pots completely?

We've used both Aluminum and steel flashing to contain canna, ruellia, and bamboo. Prefer the Al because it is easier to fold the top edge over to prevent cuts. We try to go at least 10" deep... though much deeper for bamboo. Should always consider utility, sprinkler, and pool line locations, but be especially cautious as you approach 18" depth. Might look into one of the poly root/rhizome barriers sold on Amazon and elsewhere if you have a large area to contain or will be working near any kind of underground power. This post was edited by bostedo on Sun, Nov 2, 14 at 22:58