Hi. I'm taking the Geoff Lawton online PDC right now and I've got a friend who I'm designing for as my design for the certificate. It's an interesting plot - she has a 9 year old walnut tree that can't be removed, so we've had to think about how to deal with the toxicity there. That's all been really interesting and I think we've got some really nice solutions. However, I still have a couple of issues I need to work out and I thought you guys might be able to offer some advice.
Firstly, I read somewhere that mulberries could help to shield against the effects of the walnut's juglone. Can anyone confirm if that's true?
Secondly, the client is interested in keeping ducks and wants to build a small pond for them, but the soil is only about 30cm deep and almost dead flat. Underneath that is a either the concrete roof of the underground garage or a layer of gravel. There is a slope of about 1:1 at a height of 45cm at the edge of the garage roof though, and cheap clay available locally. I wondered if it might be possible to build a dam wall directly on to the soil that's there (the soil is almost 100% clay right now) with a keyway going just 10-15cm down. Will that be safe if we seal the ground well inside? The wall would obviously only be about 45cm high.
Finally, if the pond seems like a plausible idea, what kind of plants can I grow there, either around the edges or in the water itself? Anything that can be either duck food or human food is great, but the client would like pretty things too. The garden is in southern Germany on the edge of Lake Constance. Temperatures there now are 25-30C, but they also get some of their heaviest rains in summer. Winters are pretty mild with only a few days of frost and very little snow. Local farms produce tons of carrots, tomatoes, squash, lettuces, apples, citrus, watermelons, corn, cherries and berries, amongst other things. She's interested in trying wild rice. Does that sound possible?
Any help is greatly appreciated. Thanks!