Suitable plants for river bank and ground coverage.
By Hrmorton
United Kingdom 
Hi,
We have a river running along one side of our garden we have had some slope erosion and have been advised to plant willows to help stablise the bank. Should we plant only willows, it's a 25 metre stretch and how far apart should then be.
Also we want to plant some ground covering plants on the river bank to stop exposure to the elements and prevent more erosion. It floods a few times a year, perhaps for 2- 3 days at a time.
I was hoping for some advice on the best plants to use for this task.
22 Aug, 2009
Answers
Hi,
We're only about 40-50 ft from the actual river, so I'm guessing the weeping willow is out.
Are there smaller varieties that might be suitable for this distance, or an alternative to the willow.
A geo engineer recommended the willow as what we're trying to do is give the bank more support to stop erosion.
Thanks for the quick reply.
22 Aug, 2009
It's a pity the geo engineer wasn't more specific than that! One thing that will help eventually is planting ivy - it forms a mass of roots which should hold the banks well. Because of the proximity of your house, if you want to plant a willow at all, I think I'd choose just one, a tree, Salix 'Tortuosa', which will be about 33 ft high and 23feet wide at the crown when its mature at 15 years. I don't know if you can accommodate a tree in that area, though, and perhaps two might be better, but again, not too close to the house - at least 40 feet away. I wouldn't recommend the coloured bark type - they have a very wide root spread. Other alternatives would be large shrubs, anything that produces a good root system, really. The engineer has suggested willow because it has a tendency to seek out water, I'd guess, or perhaps its a visual association in his head between willows and water! Think I'd be inclined to get in touch with him and ask why willow in particular, to see what he says.
22 Aug, 2009
Willows vary in height from 20m down to 2m, depending which variety you choose. The tallest is probably the weeping willow, at 20m high and about 15m wide, eventually. What you don't say is how far away the river is from your house - the recommended planting distance from any building or structure with willows, particularly the larger ones, is a minimum of 130 feet. If the distance from your house is that or more, I'd be inclined to put in a weeping willow - they are beautiful, but they need space, and I don't know quite what your situation is there.
Alternatively, you could use Salix tortuousa, the twisted willow, and there are one or two coloured bark varieties which are usually kept stooled to encourage new, brighter coloured shoots for winter display. But how close the river is to your house is the crucial question.
22 Aug, 2009