Butyl Liner Ponds and Aquatic Plant Roots
QUESTION ... I have a butyl liner pond and want to plant marginals around the edge. I'm worried about the roots ripping the liner though, could you tell me which plants to avoid please?
Sarah Lewis, Beeston
Butyl liners should be strong enough to cope with the intrusive roots of all marginal plants for all of its guaranteed life. Although with the ever-increasing trends towards Lifetime guarantees offered by wholesale suppliers, there must still be a point in time when things begin to crack up. I would still think in terms of 15 to 20 years as a Lifetime.
My main concern with a pond less than 15 years old would be from water loving plants outside the pool (say from within 5 metres) that can sense water on the other side of this thin fabric, particularly the trees like alder, all the willows, the poplar family and even cherries. Surprisingly Leylandii conifers and other large related species have also been a problem to clients of mine in the past.
In the pool, as the liner begins to age, particularly around the top edge, you may find the intrusive roots of the likes of Typha latifolia, greater reedmace, Scirpus lacustris, the bulrush or any of the horsetails, Equisetum japonicum and Equisetum scirpiodes.
The hard and soft rush, Juncus inflexus and Juncus effuses, can look like benign stick-in-the-muds, but give them a regular check to see that they are not misbehaving.
The water mint, Mentha aquatica is one plant that seems like a culprit, never staying where it is put, but it may just be an opportunist taking advantage of damage caused by other things. The large Loosestrife too can be tarred with the same brush as other vigorous pond dwellers, but the damage done in association with this plant is often caused in the process of getting it out of wherever it has lodged itself for the last 4 years or so. It has a very hard woody stem.
The secret of a secure pool liner is to stick to plants that DONT come with the label NOT SUITABLE FOR SMALL PONDS. Grow them in aquatic plant baskets and check these every year, if not every six months to ensure there is no adventitious root growth. If there is, cut it off!