I'm about to tackle the same kind of problem in our not so old asparagus bed. Have spoken with a friend who has much more experience in this climate, with Bermuda and with growing asparagus with this problem. If you care to, you can drop in on the Oklahoma Gardening forum and look up Mulberryknob, as she and her husband have been successfully beating Bermuda in their asparagus bed for years. Essentially one has to get as much ahead of the stuff as possible (the real problem). I intend to use a spading fork and a couple of hand tools to dig it out (carefully) around the asparagus. Then, one mulches, as mentioned above. The real key, however, is what one does this fall. After things get cold our friends dump more than a foot of leaves on top of the bed; more if possible. It's important to maintain the thick mulch, year round. The very thick mat of leaves suppresses the Bermuda as much as one can suppress the stuff. Plus, in the coming spring, what does make it through can more easily be pulled by hand. After a couple of years of this treatment they have a Bermuda free asparagus bed. It's just not going to be easy to get started. Though I won't use Roundup, I can fully understand why someone would. George Tahlequah, OK

I'm one who found the trench edge too much maintenance. To keep it looking nice and crisp, it needed work three times each season or soil washing down from the beds started to fill the trench and blur the edges. My case is a bit unusual since I'm disabled and use a walker for mobility. The trench was also becoming a hazard - if I walked too close to the edge and any of the the walker wheels dropped into the trench, I was apt to fall. The brick edging was a great relief for both maintenace and safety. We waited until we thought the beds were likely to stay pretty much stable in size and shape before we did the brick edge. We changed one the next year, which was a bit of a pain. The other thing I do - mainly in the backyard - is put a mulch path between the bed and the lawn so the grass is nowhere near the bed. The grass seems less inclined to invade the path and easier to remove - or mulch over - if it does.

Personally I think it would depend on how many beds, how large they are & soil type. If you have poor soil, you are going to have to edge your beds as often as you mow. I don't have much experience with conifers, but I have a lot of experience in gardening in general. Before when I had just a single 40' bed in the front of my house I wanted the perfect edge. I took my shovel and dug a the perfect trench and it looked great! A month or so later the edge filled in because of the drainage. I dug it a couple more times that year until winter came and had the same results. It took maybe 2-3 hours each time. The next year I went and got a gas edger (the kind you push, not the string trimmer kind) It dug the edge in about a quarter of the time of shoveling which was nice. However, I still had the same result. Last year I put a retaining wall in it's place and the problem was fixed. This year I started collecting conifers... I have 7 new large beds in my backyard. Most of them are 50' long & I plan to add at least 1-2 new beds a year. I'd be crazy to go out each month with a shovel to get the perfect edge even if I had good drainage. Actually, my roundup edge is a lot straighter than what my shovel or edger could have done. Whaas- I use roundup around the edges only when the grass starts to creep over the mulch beds. My grass is the spreading type that grows at an angle and I can't mow it once it crawls over the mulch beds. Other than that, my edge looks similar to yours. Although I only like to apply a thin layer around the edge so the grass holds the mulch back from spilling into the yard. This way the mower can go over the edge and it won't toss any mulch into the yard. I would say what you need is to rent a professional edger each spring at your local store. See link for the type our local place offers... Picture from camera phone taken today: Here is a link that might be useful: EZ Trench

Natural mulch: leaf litter from the surrounding trees It's free. You don't have to go somewhere to get it and haul it back. It never runs out. It won't contain alien organisms. It will affect the soil chemistry, allelopathic interactions, and microfauna in a way consistent with the rest of your woodland. It will look consistent with the rest of your woodland. It will be guaranteed to perform its ecological functions (absorb water, retain moisture, moderate temperature, harbor beneficial insects and other wildlife) in ways that are expected and appreciated by your native plants. By divesting from mass-produced, commercial mulch, you're "voting with your wallet" for better practices in the horticultural industry and horticulture in general. In our area, the leaf litter is mostly "pine straw". It looks great and works its magic.