Edges of the koi pond are overgrown, both by unintended invaders and ones I planted that have grown more vigorously than expected. The invaders include a small area of cattails, seeded from the nearby wetlands, I expect, and yellow flag irises that were planted in the bog area of the pond (where they have nearly been crowded out) that have spread to displace desirable Japanese irises.
In ever smaller open spaces, stilt grass has set in, with the dense growth making it difficult to gain access to pull this invader. Joe Pye weeds that grow in damp spaces between partially submerged boulders are tall growing seedlings of natives, and not more compact types planted in soil at the pond’s edge.
I debate giving in to turn the margins of the pond over to nature, for it is a laborious project to prune wide spreading Oakleaf hydrangeas so that yellow flags and cattails can be chopped out. Several snakes that reside in the dense growth are a minor concern, but a discouragement whenever I’m tempted to push through to pull a few handfuls of stilt grass.
From the start it was intended that growth should lap over boulders at the pond’s edge, so that the pond would appear as natural as possible. Perhaps this has gone too far, but there is no easy way to chop out cattails and yellow flags, and the entire mess is a few degrees wilder than I prefer.
The goal, for the pond and the garden, is to be lightly managed. This enables maintenance of this acre and a quarter with no assistance, and I much prefer a jumble of foliage and flowers rather than tightly sheared balls and cubes. But, there is a limit, and I question if the margins of the koi pond have crossed this line.
Ramblin' through Dave's Garden 
I have trouble with kaempferi Japanese iris too, and better luck with siberian iris.
What about replacing the cattails with Rogerisia, Astilboides, or Petasites or other semi-aggressive bog plants? And have you tried Lysichiton camtschatcensis for the shadier parts?
If it was easy to dig cattails and yellow flags out from between partially submerged boulders I’d gladly exchange them, and your’s are excellent suggestions. I’ll try to slowly work my way around the worst parts. It’s only twenty feet, but it might require more energy than I can give.
Dave – I adore all of the water features on your property; something that I hope to perhaps some day have (in a much smaller way) here. Are your ponds just natural clay, or are they lined with something? I know that there are a lot of options these days.
All ponds are rubber lined, so they hold a consistent water level. The liner gives flexibility in design, and without exposure to the sun it could last longer than I’ll be around.
Thanks! Is there a brand or vendor that you prefer?
I expect that there’s little difference between 45 mil pond liners.
Thanks!
Would allowing it to return to nature entail promoting the natives at the expense of the exotics?
In this case, a return to nature means that I give up on trying to control whatever, native or invasive.
Dear Dave, I like the wildness and am sure the snakes appreciate it too! Don’t prune! Enjoy your Saturday without feeling you need to cut the cattails! 😀