Water Gardening In Springtime


The water garden year really begins in March with the first shining yellow flowers of the kingcups on the marginal shelf or in the marsh garden, and, probably, the matrimonial activities of frogs in the pool. The kingcups will still be flowering well into May, long after the frogs have dispersed.

It is a good time to move hottonia but otherwise the only planting that can be done is outside the pool; alpines, conifers, ferns and waterside plants can all be planted now.

Any planned construction, whether of pool, rock garden or watercourse, can go ahead as the weather and state of the ground allow. If concrete is used care must be taken to protect the work from frost. Choose as warm a day as possible for the installation of a PVC liner and lay it out in the sun for half an hour or so – the warmth will make it more pliable.

If you haven’t already got your favourite supplier’s current catalogue, send for it now and place your order for aquatic plants so that you will be at the front of the queue when the lifting season starts in May.

Any primula or iris seed saved from last season can be sown now under glass.


Some aquatic plants, such as oxygenators and a few of the more vigorous marginals, may be purchaseable in April but the majority of aquatics will not be ready yet. Alpines, conifers and many waterside and marsh plants can be moved now. Divide and replant any overcrowded waterside plants, clean the beds and work in 2 oz. Of bonemeal per square yard – but take care to keep it out of the pool.

It should be safe enough now to disconnect and clean the pool heater and put it away until next winter; and reconnect the fountain/waterfall pump.

Be ready to feed fish liberally as soon as rising water temperatures make them more active. They are most vulnerable to infection now, after their winter fast. With increasing daylight and warmer days, and pond plants not yet making a lot of growth, algae may green the water. The plants will soon overcome this; do not change the water.

In late April iris and primula seed can be sown in well-prepared outdoor beds. Covering should equal the thickness of the seed, which means about \ in. for the iris and the merest sprinkling of coarse sand for the primulas.


Things are really beginning to move now and by the end of the month many aquatics are fit to plant.

Complete pool spring cleaning is not an annual requirement. The rule is, if all is well, leave well alone. But if overcrowded plant growth needs thinning, or if inky black or milky water suggests pollution and the need for a complete clear-out, May/June is the ideal period for it. What to do with fish is a problem if there is no reserve pool. Depending on size and number, an old bath may do. Deep barrels with small surface area are quite unsuitable. Better to make a temporary above-ground pool with polythene buttressed by peat bales or sacks part filled with soil (or anything else bulky and weighty) to form walls. Little depth (12 in. will do) and plenty of surface area is required. A shaded position is best. Fill with tap water and leave standing for a week before transferring the fish to ensure disappearance of chlorine, and no drastic temperature change on transfer.

Pump or syphon water from the pool. It is easier to net fish when it is nearly empty. Transfer them to temporary quarters with minimum handling, but take the opportunity to examine them in the net for external parasites. Transfer floating plants to provide some surface cover, and a small amount of SOP. But do not choke the temporary pool with masses of old SOP growth. Net over to frustrate cats and herons.

Split plant clumps, discard old roots and replant young off-shoots in new soil. Established water lilies will have a number of subsidiary growths round the main crown. Use a sharp knife to separate these, each complete with roots and growing shoots, for replanting, and discard the old crown. Tangles of old SOP growth go on to the compost heap after enough 6-in. Long growing shoots have been nipped off and bunched for replanting. Material awaiting replanting must be kept in water or under wet newspaper, and not allowed to shrivel in the sun.

A plastic dustpan is ideal for baling out the remaining water, mud and debris. Destroy any dytiscus beetles or larvae you find and preserve any resting buds of hydrocharis, now unfolding to develop into new plants. Clean pool sides with a stiff hand brush and plain water; do not use detergents or soap powder. When cleaning is finished refill with tap water and return replanted containers. Do not return fish until refilled pool has stood for at least three days. If they seem happy in their temporary quarters, give it a week. The new bunches of SOP cannot be given as much time as they need to get properly rooted so they must be protected from interference by the returned fish. Fence them off with rough domes of small-mesh wire netting over the containers so that fish cannot reach the shoots.

It’s back to square one now as far as pool balance is concerned and the pea-soup condition has to be endured once again. Be patient and do not change the water.

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