Planting Aquatic Plants

The best time to plant deep water or marginal aquatics is in spring, between April and June, although the submerged kinds and floaters can go into the water at any season. Bog plants move successfully in spring or early autumn.

Water lilies should either be planted in special pockets, made during the construction of the pool, or in aquatic baskets. The latter are made of plastic with openwork sides. Water lily roots are sensitive to confinement and always thrive best where they can feel the influence of water, so that concrete pockets should have a few holes punched through their sides for the same reason.

After planting, about which more details are given in the section on water lilies on p. 163, lower the baskets into the water but prop them on bricks so that they are only just submerged. The lilies must now recover from the move but when new leaves appear they can be gradually lowered until — six or eight weeks later — the baskets are standing on the floor of the pool. Other deep water aquatics such as nuphars and aponogetons can be treated similarly.Water lilies

Emergent marginals need very little water above their crowns; their chief desiderata being soil which is always very wet. Some have to have their roots confined to keep them in check. Plant these in solid pockets or suitable containers where they are to grow.

Submerged aquatics have few if any roots so tend to float if they are simply thrown into the water. Anchor them by gently pressing a thin strip of lead around two or three stems and then throw them in. Floaters are simply placed on the pool surface and bog plants inserted — like land plants — with a trowel or handfork.

Pool Depths

Garden pools should be deep enough not to freeze solid in winter, yet sufficiently shallow for the water to warm up quickly in spring. The last is essential for early flowers and in practice means 18 to 24 in. of water above the floor level. Since fish feel the effects of heat they benefit from the greater depth in hot weather, although fountains and waterfalls also help cool the water.

The marginal aquatics only require 3 to 4 in. of soil and the same depth of water, so a shallow trough surround (with its inner edge 1 in. lower than the outer) is sometimes built on to the deeper part during construction. When the pool is full of water this flows over to the outer contours and the trough does not show.

In the case of informal rock pools it is also expedient to build pockets for bog plants where they can be flooded over in dry weather. Alternatively, for large bog gardens, the soil can be taken out to a depth of 12 in. and the area lined with 500 gauge polythene sheeting. Holes should be punched in the sides of this, 6 in. up from the base, so that although it holds a certain amount of liquid it never becomes completely waterlogged. A 3-in. Layer of stones or brick rubble is then laid for drainage and the soil returned.


Water plants rarely need feeding, except for water lilies which have been three or more years in their baskets. These can be helped by giving them nutrient pills. Mix equal quantities of wet clay and bonemeal (wear gloves when handling the latter) and mould into tennis ball-sized ‘pills’. Push one or two down to the roots of each lily. After a further two years the baskets should be lifted and the lily roots washed, divided and replanted in fresh compost.

Remove old flowers and dead leaves regularly, also seedheads from aquatics likely to become too prolific.

Winter Problems

Falling leaves from nearby trees should not be allowed to accumulate in ornamental pools. Dredge them out with a rake or else make a light framework of 1-in, batons and plastic mesh netting. Lay this over the pool during leaf fall and most of them will be caught.

All pools should be kept full of water in winter and the shallow types protected against a complete freeze up. The installation of a pool heater will keep a small area free of ice and so safeguard fish and plants. Another idea is to float a block of wood or a large ball on the surface and when ice forms take it out by pouring boiling water on top. Now bale out 1 in. of water and cover the hole with plastic sheeting or hessian. The ice will then act like a greenhouse and protect the plants and fish underneath. Naturally, as soon as a thaw occurs, the pool must be topped up again with more water.

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