GARDENING: Brian Kidd on how to keep your pond fresh in a heatwave

Love island - a heron attracted to a potential, but plastic, mate.
Love island - a heron attracted to a potential, but plastic, mate.
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We have been plagued with duckweed on the pond’s surface again this year. This tiny green floating plant is a real nuisance and if not treated completely covers the surface so it’s impossible to see the fish.

In the winter we managed to clear the entire surface by lifting out sheets of ice, a cold job but the duckweed was encased in the ice so it was removed and plonked straight in the compost bin – great.

But if just one little piece is left behind the weed breeds like mad and in spring we were back where we started.

Off to the garden centre to see if there was a product to do the job. There was. We followed the instructions ensuring none landed on other plants’ leaves, so we carried out the treatment before water lily leaves appeared, and waited with bated breath. It didn’t work. Back to the drawing board.

We now have a team effort combating this problem. David, our grandson, uses the hose and squirts water over the pond’s surface while I stand on the opposite side using a fine fishing net to scoop up the duckweed. Previously I have just used the net to scoop up the weed but using the hose means we remove far more duckweed in a shorter period of time. Why didn’t we do this before?

We had another problem aggravated by the hot spell in late June – blanket weed. This grew so rapidly I was worried the pond water would overheat or the water would lack oxygen so decided to use the barley straw method of controlling it. First of all the worst of the weed was removed, about half a barrowload – it is a large pond. This was done using a rake and a lot of oxygenating plants were removed at the same time. But we could see the fish again.

Instead of using barley straw floating mats, we used a product – Pond Clear – which contains bacteria found in barely straw. It’s expensive so we bought the largest size as it may need another treatment. It worked. A lot of the weed turned yellow and floated on top of the water and was again removed with a rake. That which clung to the pond’s sides simply turned black and disappeared.

We’ve had regular visits from a heron which has the cheek to sit on top of the hedge overlooking the pond, eyeing up the fish. It swoops down and gobbles them up. We were angered by this and decided to buy a plastic heron to keep real ones away. Ours didn’t. The heron came down and tried to mate with the plastic one!

So we bought an electric fence to go around the pond’s edge, turned it on and watched. The heron arrived, walked up to the pond, got a shock and flew off. A few days later it returned and instead of walking across the grass to get a shock, he landed on a large area of water lilies to grab the fish.

The pond is now covered with wooden frames and wire mesh. It spoils the look but at least the heron can’t go fishing. But when we want to skim off the duck weed, all the frames have to be removed from the pond. Another job we could do without.

THIS WEEK’S TOP TIP

Plant nerine, amaryllis and colchicum bulbs. Choose a spot where they can bask in the sun and they’ll give much autumnal pleasure. They may not be at garden centres yet, but  I mention it now as they’re snapped up quickly.