We often are asked questions about how close willow trees (and other vigorous, damp loving species such as Poplars and Alders) can be planted to a house or drain.
The easy answer is “not close at all”. A willow may look beautiful (what is more delicate than a golden weeping willow – Salix sepulchralis Chrysocoma) but there is a monster lurking below. In their class, willows have to be the all time root producing world record holders. Their tentacles will sniff out water and – even better – drainage at long range.
I really have no idea what their maximum reach is, but I think it would be wise to leave AT LEAST 10 metres between tree and drain. If it were me, I might up that to 15 metres.
And here is why – a new horror movie available to you only on this screen-
The Willow from the Black Lagoon
More seriously, the point is that this (poor) little grey willow (Salix cinerea) which produces some of the most beautiful catkins in the willow world is between 2-3 years old and was pulled out of a downpipe owned by a friend of Rebecca (who works at Ashridge and brought the creature in. The film does not lie – the roots are well over 3 metres long while the plant is about 1.50 metres. The root mass is perfectly tubular and perfectly SOLID. Apparently it was a real tug of war to get it out and another year would probably have seen it a metre longer and completely immovable.
So keep them away from drains…..
Wow, a willow monster indeed – if we could grow carrots like that we’d be very happy….must sow some in the drain pipe next year! 🙂
The roots of a plant cannot get into drains that are not damaged. If no water can leak out, there is no way the plants can detect the water inside the pipe. Planting near a drain may be a risk – it is not always possible to know if drains are damaged – but providing the pipes are sound, the roots cannot get inside the pipes. If the pipes are cracked, any plant root is likely to block the pipe in time.
You are correct of course. And generally modern drains are plastic and leak free.
The purpose of the willow root in drain video was first to show the astonishing mass of root that one seemingly small plant can produce and second to make people aware of the RISK of planting trees close to drains. It is a little bit like planting trees too close to foundations. IF the foundations are concrete and IF they are uncracked, then tree roots are most unlikely to do any damage. But the tiniest crack and a root will find it. If it is the root of a long lived woody plant, it will oven the crack just as if someone was smashing a wedge into it with a pile driver. It just takes longer. So we never advise people to take the risk.