This year’s weed clearance has been more fun than usual. Here is Seb rowing freshly-cut curly pond weed to the bank, with a rope tied to a rake and stuck into the mass of vegetation. I am catching the stray bits and pushing from behind.
The raft of weeds is a lot bigger than it looks, because it is floating almost submerged like an iceberg, scraping along the bottom. Each of the two rafts we needed produced four barrow loads piled like this:
I cut it using an old scythe swept along the bottom of the pond, leaving the weed to float to the surface to be collected.
Left to itself, curly pond weed (Potamegaton Crispus) can take over the entire pond. When it first arrived, probably brought by ducks, I saw it as an enemy and tried to clear it all. But I have changed my mind, and now think it is an ally, because studying it for longer has convinced me it slows down blanket weed and duck weed, both of which are pernicious. The water looks much healthier for it. And today we have seen several of our pond’s water voles feasting on the little flowers, a change from their diet of reeds (and just about everything else we have planted round the bank!)
The drawback with curly pond weed is that once it finishes flowering later this month it will sink to the bottom and rot away, returning nutrients to an already over-rich pond. By clearing away two thirds of it to the compost heap I am slowing that process and removing some of the excess nutrients that I believe encourage bad weeds.
Curly pond weed grows from rhizomes on the bottom and has a form called a turion which looks like a seed but is in fact a bud that lies on the bottom through the winter and sprouts in the spring. In the spring and summer, the plant shades the water, keeping the temperature down – blanket weed and duck weed spread faster in warm water.
Next step is to find out how well our harvest of weeds works as a compost.
The shade and cooling provided by curly pond weed disappears next month, but we now have a collection of 10 water lilies of seven different varieties whose leaves do the same through the rest of the summer. We are aiming to cover about a quarter of the surface with them eventually, to provide the same shading effect.
the pond blog 