We have been making a major, combined effort to return our natural stream closer to something resembling pristine condition. I say natural stream because it is entirely natural where it enters and leaves our property but in between we manipulate it quite a bit. We have ponds, we play with the levels to create little rapids so we have the sound of water running and we have total control over what happens with flood water when we get torrential rain – achieved by a simple weir, flood channel and stopbanks. What we don’t have control of is the build up of silt and invasive water weeds.
What started as a pleasant summer activity reducing the water weeds (Cape Pondweed, oxygen weed and blanket weed are the worst), has grown to be something more major. We have hand pulled and raked most of the weed out. The clumps of streamside planting (mostly irises but also bog primulas, pontederia and a few others) are all in the process of being dramatically reduced in size. We hadn’t noticed quite how large they had grown in the years since they were first planted. The build up of silt in the water channel – up to my knees in places – is being stirred up and then flushed through to settle in the ponds. To flush it through requires holding the water back and then releasing it in one swoosh. To do it properly requires the building of a second, simple weir. Once all the silt is in the ponds, we will hire a sludge pump to clear it. Trying to stay on top of water weeds (none of which we introduced ourselves) is an ongoing task. We are thinking a bit more regular maintenance may keep the silt under control. Our access makes getting a digger in very difficult and the mess afterwards is such that we prefer to do things by hand.
The end result is that we will have a natural looking stream again. Sometimes it takes a lot of work to achieve and maintain a natural look in a garden.
1) Continue reducing mossy cover and lichen on rocks and paths in the rockery. In our humid climate, we have continual moss growth and while some of it softens hard lines and adds a certain look, too much of it obliterates lines altogether and makes the place look unloved. I use a wire brush and I know I will probably have to continue doing it for the rest of my gardening life here.
2) And on the theme of having too much of something, no matter how good, I need to finish my radical thinning of the black mondo grass (ophiopogon) and the cyclamen hederafolium which seem determined to try to choke each other out. The mondo grass goes on the compost heap. The large cyclamen corms I am laying as ground cover in an area where I have given up on both Rubus pentalobus (orangeberry) and violets which both proved to be too strong growing.
A fortnightly series first written for the Weekend Gardener and reproduced here with their permission.