For most gardeners, there is something quite irresistible about the thought of getting plants for free, whether to increase your stock or obtain something completely new. Although growing new plants from seeds and cuttings is often thought of as an activity more at home in the potting shed or greenhouse, the keen water gardener need never feel hard done by, since many kinds of aquatic plants are surprisingly easily to propagate – if you know how.
A large number of water plants can be propagated by division – and this is especially true of most of the common marginal’s, including Acorus calamus, Caltha palustris, various kinds of Ranunculus, Sagittaria sagittifolia and Typha latifolia. Choosing the right method depends on the plant’s root system. Those with fibrous or creeping roots, such as Typha,can lifted and then simply pulled apart by hand – or levered apart between two forks if the clump is a big one and the root mass too heavily intertwined. Any dead leaves should then be pared away and the roots pruned to encourage fresh growth, before potting the new pieces into their own containers and submerging them in 3 or 4 inches (7.5 – 10 cm) of water.
For plants which produce rhizomes – the likes of irises and Acorus, for example – the root mass needs to be roughly separated by hand and then cut into individual sections, each comprising a few healthy new shoots and supported by a good root system. Long roots should be trimmed back with a sharp knife or secateurs to around half their original length and then the sections planted – with the rhizome covered with only a thin layer of soil and gravel top dressing.
Submerged oxygenators, such as the invasive Elodea canadensis and the native Potamogeton crispus, are very easily propagated during the summer from cuttings – and this also helps to keep these fast-growing plants in check, as well as ensuring fresh, young stock. The job could hardly be easier – simply pinch off healthy-looking side shoots, pot, either singly or in small bunches and submerge. Typically within little more than a fortnight the newly rooted plants should be ready for use.
Some creeping marginals can also be propagated by taking cuttings, including Mentha aquatica and Myosotis scorpioides – but these should be planted singly, not in bunches, to guarantee the best chance of success.
Some kinds of floating tropical water plants – including water hyacinths – naturally propagate themselves by making plantlets, often as offsets or on the end of long shoots. In their native habitat, this helps them to colonise a pond or river very quickly – but in the temperate climes of Britain, they seldom survive long enough without winter protection to become the invasive nuisance they are back home. Simply breaking the plantlets off and putting them back on the surface is all that is required to make a new plant – though if you want to keep it for next year, you’ll have to find it somewhere warm to sit out the cold weather.
Collecting your own seed from water plants and then trying to grow it can be an interesting pastime, often producing some surprising results, but the easiest – and probably quickest – way to get pond plants for free is to make friends with other pond keepers. While one of the great joys of a well set up pond is the speed with which aquatic plants will make the water their own, vigorous growth can often lead to them becoming rather too successful for their own good. Many water gardeners will need to do a spot of thinning out over the season, which provides a great opportunity to acquire some new specimens for your own pond. By the same token, you might want to consider offering fellow hobbyists any plants you have in over-abundance; after all, they do say that a fair exchange is no robbery!