Water plants and cold
A beautiful spring garden lays its roots on the work done in autumn, a job used to clean, fix and repair the garden and plants in autumn; this "rule" also applies to the water garden, which requires some care in autumn, so that it can then shine with its natural beauty in spring. Most of the most widespread varieties in water gardens are rustic species, which are well resistant to cold temperatures and frost, without major problems; enthusiasts, and those who are always looking for particular or exotic flowers, place plants that are not completely rustic in the aquatic garden, which may have some problems in the case of intense and prolonged frosts. To take a trivial example, water lilies are very common and widespread, and most are hardy and resistant plants, which are ruined only in the case of very intense frost, which leads to complete freezing of the water of a small shallow pond . However, there are many species of tropical water lilies, which produce flowers that bloom above the surface of the water, very decorative and fragrant: these water lilies, much more beautiful and showy than the common water lilies, are not rustic, and need higher winter temperatures at 10-12 ° C.
So the commitment of the gardener in the water garden before winter arrives is of two types: on the one hand you will have to perform routine work to prepare the pond to freeze, on the other you will have to do extraordinary work for the species that fear the colder climates, which should be properly treated.
Water plants that fear frost
As we said, there are not many species (such as tropical water lilies, euryale, some varieties of indica cane and some other aquatic plants) that fear intense and persistent cold; for this reason, these varieties can live outside only in Italian areas where the winter climate is mild, without frost, or with short and sporadic frosts. Throughout the rest of the peninsula, during the winter they find a place in sheltered places, like a greenhouse or even at home. To be able to move them to the shelter we will have to equip ourselves with special vases, where we can find at least 25-30 cm of water and our plants; let us therefore consider some very large vessels, without holes for drainage (since we will have to put water in them), possibly transparent and possibly made of plastic, otherwise they would become too heavy once filled with water.
Transfer and care
Found the container we unearth the plant from the bottom of the pond, or take it from the surface of the water, and position it in its temporary home, and we post the container in a sheltered and bright place. Throughout the winter we will check that the water in the jar does not evaporate excessively by lowering its level. Since the pot will remain in a sheltered place throughout the winter period, with mild temperatures, it is good to check the presence of mosquitoes, to prevent our tiny transportable pond from becoming a mosquito nursery: therefore we dissolve mosquito repellents in the water, possibly in base of bacillus turingensis, so as to harm only mosquitoes. If we have a lot of space, or small varieties, we can insert more plants in the same container; if we have only species that live with the roots in the soil on the seabed, instead of keeping them in a miniature replica of our pond, we can decide to prepare special vases, which will become mini lagoons, in which to winterize our plants, to transfer them back to opened in spring. It is generally what is done with papyrus in many Italian homes, where it is commonly grown as a houseplant. So let's choose a nice vase, and let's use it to bury our aquatic, using a light soil made of sand and peat in equal parts. The pot must be kept constantly immersed in water for at least a quarter or a fifth of its depth; therefore we will find a basin, a saucer, a cache-pot that is a few centimeters wider than the vase, and throughout the winter we will check that it contains at least some water. These mini lagoons can be grown in the apartment, in a bright place, obviously away from direct heat sources.
The pond in winter
Hardly in Italy the cold is so intense that it completely freezes our pond in the garden; if we live in a very cold territory it would be advisable to empty the pond during the winter, storing all the plants in pots or in greenhouses, and also removing all the water, to prevent the ice that would form with it go to deform or ruin the bottom of the pond and the material with which it is built. After having emptied it, let's clean it and if we want to cover it with a cloth, it will wait until spring to be rearranged again. If, on the other hand, we have a large lake, perhaps even a deep one, which does not risk freezing, we can safely leave it full of water; it is good in any case to turn off and eventually remove waterfalls, sprays or small fountains, which could freeze and therefore need to be replaced in spring. If possible, let's remove them and place them in a greenhouse or cellar. If we still have some plants of which we do not know the rusticity we can try to cover it with non-woven fabric, or to mulch the roots with mud, so that they are deep enough in the soil not to suffer excessively due to the intense cold.