The flora of the water gardens
From a biological point of view, the ensemble of all aquatic plants can be reduced to three groups:
- that of plants for moist soils
- that of marsh plants
- that of aquatic plants , both fixed to the bottom and floating.
They differ in their physiology and it is necessary to have some basic knowledge for their use. Due to the considerable choice of all these plant groups, some plant species will need to be selected. If you have a small garden with a small tank, it is useful to keep in mind that real aquatic plants, living under the surface of the water, are less visible than marsh plants and for wet soils whose leaves and flowers, often noticeable , exceed the level of the water surface. Since it is not possible to cultivate all of them, the latter will be favored over the former. On the contrary, if you have a large lake where all the water heights necessary for plant cultivation are represented, it is evident that the choice of plants will cover all the groups mentioned above.
PLANTS FOR WET SOILS
Plants for humid soils occupy a particular area by exploiting the presence of fresh but ventilated soil and a humid atmosphere thanks to the presence of water which is essential for their survival. These plants don’t necessarily grow near a pond. Occasionally they can be found in undergrowth, near springs, along drainage channels or in valley bottoms with marshy soil. They endure short periods of drought but degenerate if they are deprived of water for a long time. Their importance in the furnishing of a garden is fundamental for two reasons: they are often more colorful than purely aquatic plants and also allow with their generous vegetation to enlarge the space around the pond giving the impression that it seems larger than it is. actually.
THE PALUSTRIAN PLANTS
“The feet in the water and the head in the dry”: marsh plants occupy that transition zone between the domain of water in the strict sense and the rest of the garden. The upper part of the plant, foliage and flowers, grows above the water level, while the collar and root system are located in the water. The epidermis of the aerial organs is often covered with a waterproof cuticle with stomata. The cuticle prevents the plant from drying out, while the stomata ensure the functions of chlorophyll assimilation, transpiration and respiration, elimination of water vapor and gas exchange. The parenchyma (tissue that forms the active part of a plant organ) of marsh plants is somewhat similar to that of certain aquatic plants, insofar as it contains air-bearing gaps. The conductive tissues are highly developed; the fabricsof support of the cellulosic or lignified walls are always present and ensure the rigidity of the aerial organs. The root system is very developed, it serves to maintain and allows the absorption of nutrients dissolved in the water or present in the substrate. Thanks to this organization, these plants do not fear desiccation.
AQUATIC PLANTS
Their epidermis is generally green, without cuticle or stomata, but nevertheless permeable to gases and salts dissolved in water as in oxygenating agents. In those that have floating leaves, such as water lilies, the upper epidermis in contact with the atmosphere has cuticle and stomata. The air gaps are more developed and allow the leaves and stems to be supported by floating. Generally these plants are fixed to the substratum with short roots, except for plants that have tubers or rhizomes, such as water lilies. The conductive tissues are very small since it is the epidermis that absorbs the nutrients dissolved in the water. Their transpiration is almost nil and drying cannot take place; gaseous exchanges are carried out by diffusion through the epidermis of the stem and leaves.
VEGETABLE PHYSIOLOGY
All these plants, whether they are for wet, marshy or aquatic soils, are linked to four limiting factors (law of the minimum), imperatively conditioning their life, their growth and their reproduction. They are light, carbon dioxide, temperature and nutrients. The first three factors are intimately linked and participate in the primordial function which is chlorophyll assimilation or photosynthesis. To this is added the plant nutrition process starting from organic and mineral substances.
Nymphaea: queen of water
Well anchored to the bottom of the lakes, they let leaves and flowers float on the water. Water lilies since ancient times they aroused admiration and veneration among the peoples of Asia. The Egyptians have left us through the frescoes of the temples and tombs a faithful representation of the white-flowered Nymphaea lotus and Nymphaea caerulea, the famous blue lotus of Egypt, two tropical species that populated the ponds of the Nile valley 5000 years ago. Another species of blue water lily, Nymphaea stellata, was, in India and China, the sacred flower of Buddhists in the same way as Nelumbo nucifera, the sacred pink lotus of Asia. In Europe, Nymphaea alba and white-flowered Nymphaea candida were the basis of numerous myths and popular beliefs. They symbolized beauty and elegance for the ancient Greeks, who saw in them the representation of the Nymphs and water spirits. For the peoples of Central Europe they had the power to ward off evil spirits. In the last century they inspired great painters such as Monet who painted his famous paintings in his garden in Giverny. Today these beautiful aquatic plants are grown as ornamental plants. The simplest to grow are hardy water lilies. They completely disappear during the bad season and are able to withstand the harshest winter, provided their rhizome is kept above freezing. All water lilies love They completely disappear during the bad season and are able to withstand the harshest winter, provided their rhizome is kept above freezing. All water lilies love They completely disappear during the bad season and are able to withstand the harshest winter, provided their rhizome is kept above freezing. All water lilies love sunny locations and hot water. The daily sunshine hours should be at least six to promote good flowering. There are few varieties that bear semi-shaded positions (Hermine, Comanche). These plants begin to vegetate in late winter as the water begins to heat up. The leaves develop first and only later, in mid-spring, do the flowers appear. The greatest growth occurs in the hot months of summer. In autumn as the temperature decreases, growth slows to a complete halt at the end of October. Depending on the species, the planting depth can vary from 15 to 200 centimeters. The rhizome firmly anchors itself to the bottom earth and produces long petioles which end at their ends with a solitary leaf. The submerged leaves during growth are rolled up into a croissant. The flowers, which can reach 20 centimeters in diameter as in the Attraction, open at ten in the morning and close at five in the afternoon for the entire flowering season which runs from April to September. After fertilization the petals and sepals close to form a globose and leathery fruit that can contain up to 1500 seeds. The fruits detach after ripening to overwinter at the bottom of the pond. In spring the seeds rise to the surface to be dispersed by the wind and waterfowl. Each water lily is able to cover about one square meter. Limiting the leaves is a small trick that will allow us to obtain a more abundant flowering.
At what depth should they be planted?
It is important to respect the typical indications of each species. A depth of 60-80 centimeters, however, satisfies the need for most water lilies. Shallow water heats up quickly and promotes generous and early flowering. In small ponds we choose species of reduced development that adapt to grow even in 15 centimeters. In large ponds we choose species of great development that withstand depths of 200 centimeters; keep in mind that flowering decreases at this depth.
What kind of land do we use?
Water lilies love common garden soil, preferably clayey and a little slimy, rich in organic substances. We avoid the addition of manure, as many suggest, because by osmosis such a high quantity of nitrogenous substances would be released into the water as to cause an uncontrolled growth of algae. If the soil used is excessively poor, we use a slow-release balanced fertilizer that will be placed on the bottom of the pot.
How do we plant water lilies?
The rhizome must be buried up to the leaf collar, slightly inclined, so that the terminal part touches the wall of the pot while the growth apex can develop towards the center of the pot. In large natural ponds, water lilies must be planted directly in the bottom silt. If the water level cannot be lowered, we tie a stone to the rhizome and throw it where we want the water lilies to appear. In an artificial pond we can cultivate them in the same way after having prepared the bottom with twenty centimeters of earth and five centimeters of sand. Otherwise we grow them in plastic containers of at least thirty centimeters in diameter. This method allows us to better control the growth of plants and intervene for the division at the right moment.
Oxygenating plants
These plants, which live completely submerged , are neither spectacular nor beautiful but certainly the most useful. Present in a certain quantity, they ensure clear water. Oxygenating plants play a fundamental role in the life of a pond. They release large quantities of oxygen during the day, an element of vital importance for all living organisms in the pond. Their number must be proportionate to the amount of water present in the pond. If they were in small quantities, oxygen would be insufficient, algae growth would be favored and the water would turn green. If they were too many, they could stifle the growth of other plants. It will be useful to plant them in pots to avoid excessive proliferation and invasion, which is difficult to contain if they were planted in the ground. In addition to oxygenating these plants, they offer an excellent shelter and food to all newly born fry, often easy prey for adult fish.
Elodea canadensis (oxygenating)
This perennial and rustic plant takes root easily at the bottom. It forms long stems that touch the surface. Its growth is rapid in early spring, stabilizing as the season progresses. To reduce its volume, it is enough to tear off some tufts with the same hands. Very effective oxygenating plant, it is grown very easily. It should be planted 30 to 150 cm deep, better in pots to control development.
Ceratophyllum demersum (oxygenating)
Excellent oxygenating plant. Its stems produce numerous small finely divided leaves; this prevents obscuring the bottom of the pond despite a very vigorous vegetation. It can be planted in pots or left to float freely.
Hippuris vulgaris (oxygenating)
Planted deep, it remains totally submerged. In shallow water, the stems rise up to 40 cm. above the surface to form small fir trees. It has a good oxygenating power.
Floating plants
They seem to live on fresh water. Some are “pests”, due to their excessive development, others jewels, due to their strangeness, but all are extremely useful in cleaning the water of a pond. They are plants that float freely on the surface of the water. The leaves are structured to contain micro-bubbles of air that allow the plant to float. They produce masses of roots that grow under water and absorb the mineral salts dissolved in it. For this reason they are very useful as biological purifiers, reducing organic pollution and avoiding water numbness. Some are tropical and can’t stand the harsh winters of our latitudes. If they are to be kept for the following year, in October they must be collected in a heated greenhouse or at home. It is enough to use a small plastic container; the bottom is covered with a centimeter of silt recovered from the pond, covering it with sand, it fills with water from the pond and settles in front of a window in full light. A balanced liquid fertilizer should be used every fortnight.
Rustic floating plants
Lemna minor or duckweed. It is very intrusive, covering the entire body of water, subtracting light from the oxygenating plants. It is easily eaten by fish. Trapa natans or water chestnut. Very beautiful due to its emerald green rhomboid leaves, it begins to produce seeds as large as a chestnut at the end of summer with hard and sharp thorns. When the plant dies before winter, the “chestnuts” fall to the bottom. In spring they sprout forming new seedlings on a long stem that grows to the surface.
Stratiotes aloides or water pineapple. In winter it rests on the bottom to overwinter. In spring it rises to the surface. Forms of colonies by vegetative multiplication. It produces beautiful white flowers from May to July.
Tropical floating plants
Eichornia crassipes or water hyacinth. It is a very beautiful plant that produces a magnificent blue mauve flower from July to September. It is composed of a rosette of leaves whose petiole is enlarged into a ball giving it a very curious aspect. Due to its intrusiveness, few plants are needed in a pond.
Pistia stratootes or water lettuce
The thick, light green leaves arranged in a rosette are vaguely reminiscent of a lettuce stump. Its highly developed roots are used by the fry as a refuge. It is very intrusive.
Marsh plants
Their leaves and flowers grow free in the air, but the roots grow in water and do not tolerate dry soils . Marsh plants populate the area that joins the land to the water. In a natural lake, their arrangement is simple as they can be planted directly in the silt of the bottom near the shore at the desired depth. In an artificial pond, these plants should be placed along the edges. A wall of bricks or stones resting on the bottom can be useful to contain the earth, preventing it from falling downwards. Most of these plants have a great vigor and in medium-small ponds they should be planted in pots to control their growth, cutting the roots regularly and dividing them every two or three years. If levels of different depths were not foreseen at the time of the construction of the pond, it is often necessary to use bricks for the vases in order to raise them up to the surface of the water. When choosing the number, the rule is to avoid an excessive mixing of different species. Better a small number of varieties with numerous specimens for each group.
Houttuynia cordata
Excellent ground cover. Ideal for masking the rocks used to cover the edges of the sheet. Leaves and flowers smell of unripe mandarin. It grows in any position.
Butomus umbellatus
It stands out for its inflorescences that culminate with about fifty pink flowers grouped like an umbrella. It forms colonies quickly if the soil is very rich in nutrients. Likes sunny locations.
Scirpus tabernaemontani
It forms dense colonies of tubular stems up to one and a half meters high that oscillate with the gusts of wind. The “Zebrinus” variety is horizontally variegated with white and green stripes, the “Albescens” variety is vertically variegated with yellow and green. They grow well even in partial shade.
Sagittraria sagittifolia
it is a plant able to adapt to live in all positions by changing the shape of the leaves according to the planting depth. If planted on the bottom it produces ribbon-like leaves. At the surface of the water they become lanceolate. When the plant is on the edge it produces sharply sagittate leaves.
Lysimachia punctata
Easy to grow, Lysimachia grows quickly, whatever the soil or exposure. The flowers, shaped like yellow bells, are grouped in spikes. The plant reaches a height ranging from 60 to 120 cm. It should be planted at a depth of 10 cm. at the rate of six plants per square meter.
Glyceria maxima ‘Variegata’
This beautiful grass is ideal for populating the edge of tubs. With its very long variegated leaves, which move with every gust of wind, it animates the shore of the pond. Its root system is beneficial for the solidity of the embankments. It can be planted up to 50 cm. in depth, at the rate of 10 plants per square meter. In small tanks it is best to plant it in a basket.
Equisetum hiemale
Horsetails are much feared in gardens, but they find their ideal place in ponds. Their very attractive stems reach a height of 120 centimeters and remain green throughout the winter while around them, most of the water plants disappear.
Aquatic irises
They must never be missing at the edges of a pond. Their flowers are splendid, even if short-lived, and their linear and vertical leaves contrast with the horizontal plane of the water. They must be divided into two groups: Aquatic irises can live in the water all year round as the genera ‘Laevigata’, ‘Pseudacorus’, ‘Versicolor’, ‘Setosa’ and ‘Luisiana’. Marsh irises do not like to have their feet in the water even during the winter rest like the genera ‘Ensata’ and ‘Sibirica’.
Orontium aquaticum
The flowers of the orontium resemble large matches or candles lit on the water with the yellow tip and the long stem. A very unusual flowering. To appreciate it, starting from March, it is best to plant it at the edge of the tub. The plant forms a very dense clump of bluish green lanceolate leaves. It reaches 45 cm. in height and it takes six per square meter.
Juncus effusus
The rushes are perennial and rustic plants, they have cylindrical stems and leaves. Their brown fruits are interesting as in Juncus ensifolius. Certain varieties can reach 1.5m in height. Juncus effusus ‘Spiralis’ is very decorative with its spiral leaves. You have to plant them very close to get dense tufts, more pleasing to the eye.
Marsh primroses
Of all the perennial primroses for wet soils, those grouped under the name of ‘Primula candelabre’ are certainly the most spectacular. They produce flower stems 40 to 90 cm tall. on which at regular intervals flowers of different colors bloom. Among the most recommended: Primula japonica (pink, red or white), Primula bulleyana (yellow and orange), Primula beesiana (magenta pink), Primula florindae (yellow). They must be planted flush with the water.
Mentha cervina
The mints are perennials, rustic and honey-bearing. There are over a thousand varieties of which some thrive in shallow water. It is best to grow them in pots to control the expansion of their very vigorous roots.
Thalia dealbata
This beautiful rustic plant of subtropical origin has glaucous green solitary oval leaves, with a horizontal bearing on long stems at the end of which a spike of purple flowers develops. Due to its elegant profile it is a precious plant to create an exotic setting. It does not tolerate frost but it is sufficient to place the stump under the freezing line.
Pontederia cordata
It is a plant widely used in the decoration of a pond. Its lanceolate leaves are very decorative and much appreciated are its lilac blue flowers that bloom in summer, when there are no other flowering plants. Likes sunny locations. It reaches a height of 90 cm. and to fully appreciate its posture it is necessary to plant it in groups freely or in large pots.
The Lotus flower: symbol of purity
Known since ancient times, the lotuses are part of the oldest cultivated plants. The symbolic content of this plant is extremely powerful in the Buddhist religion. In temples there are often tubs filled with lotus. Buddha is represented seated on a lotus flower which represents the purity of the muddy waters. Nelumbi, in Asian countries, are also cultivated for food purposes. All of it is consumed. The seeds are roasted, the rhizomes replace our dear potatoes and the young leaves, when still wrapped around themselves, are used to make excellent soups. Apparently nothing is worth a good lotus leaf soup for a peaceful night. Vietnamese often give their slightly agitated children a lotus seed before going to bed with surprising effect. The Chinese grow a variety of lotus with more stocky rhizomes and closely spaced internodes for purely food purposes. Lotuses are native to the Indies, the banks of the Volga, northern Australia and North America. Instead, their presence on the edges del Nile is due to a human intervention towards 500 BC. The Nile lotus exists, but it is not a nelumbo, but a blue water lily, the Nymphaea coerulea endemic to the river. It is a rare tropical botanical water lily, which is often found depicted in the frescoes of Egyptian temples. Although very different from the morphological and vegetative point of view, lotuses belong to the Nymphaeaceae family, even if some authors still today, continue to insert lotuses in the Nelumbonaceae family. The vegetation of these plants is extraordinary. Only the first leaves, like water lilies, float on the water, while all the others soar towards the sky. The largest varieties reach a height of 180 cm. The flat or slightly funnel-shaped, dark green, bluish green or bronze green leaves are supported by slightly thorny peduncles. The flowers emerge from the foliage to bloom in full sun. The banana-shaped rhizomes, white in color, are crossed by channels. When they develop they produce a very long stolon which at the level of the nodes gives rise to secondary rhizomes. There are only two botanical species of lotus: Nelumbo lutea, native to the United States, and Nelumbo nucifera, native to the Indies. Latour Marliac was the first breeder to obtain a lotus hybrid: Nelumbo ‘Flavescens’. In America, dozens of cultivars have been obtained from numerous breeders. Almost 300 are the cultivars that the Chinese have obtained in the last twenty years. Most are small in size.
LOTS IN THE AQUATIC GARDEN
Lotuses are of great decorative interest. Their presence gives an exotic note to the whole body of water. At the edge or in the middle of the water mirror, they grow with luxuriance typical of tropical plants but without having their fragility. Only the director Victoria stands up to him. When you are lucky enough to be able to make the two species cohabit in the same tank, you get the impression of being in the land of a thousand and one nights.
CULTURE AND MAINTENANCE
The cultivation of lotuses does not present particular difficulties if these simple tips are followed. The lotuses want a sunny area from morning to evening so that the water can reach a temperature of 25 degrees as the season progresses, a primary condition for stimulating flowering. Sustained fertilization is a prerequisite for lush vegetation. It should be borne in mind that lotuses are capable of producing stolons longer than six meters in one year. The rhizomes of the previous year go to die to feed the future vegetation and flowering and at the same time they must find enough resources to remake the rhizomes of the future year. These plants should be grown either in closed tubs or in areas of your pond that are isolated from the rest of the pond. In any case, if you do not want your aquatic garden to become a virgin forest, you must imperatively block the advancement of the roots. The ideal space to appreciate this plant should be 2 m2 of surface by 60 cm of depth, of which 40 cm filled with substrate and 20 cm. of water. To insert the fertilizer without difficulty in spring, it is necessary to wait for the first floating leaves to appear, then wrap the fertilizer in a sheet of newspaper, make holes with the help of a stick and insert these candies into the holes by closing them. immediately after. The method is simple and effective when the water level cannot be lowered and the newspaper degrades quickly. For a first plantation, the fertilizer will be hidden under the entire surface, then a groove of the shape and size of the rhizome will be traced with a depth equal to three times its thickness, a dose of fertilizer (50g) will be applied and then slightly covered with substrate. The lotus will be deposited in this excavation, the lotus will be buried, taking care to leave the tips of growth free from the ground; above all it is not necessary to crush the substratum because the plant is very fragile like glass, finally a flat stone will be placed across the rhizome to ballast it and fill it with water without causing turbulence. the lotus will be buried taking care to leave the growth tips free from the ground; above all it is not necessary to crush the substratum because the plant is very fragile like glass, finally a flat stone will be placed across the rhizome to ballast it and fill it with water without causing turbulence. the lotus will be buried taking care to leave the growth tips free from the ground; above all it is not necessary to crush the substratum because the plant is very fragile like glass, finally a flat stone will be placed across the rhizome to ballast it and fill it with water without causing turbulence.
Tropical water lilies and Lotus flowers
Tropical water lilies are even more spectacular than rustic ones because their flowers are large, they are emerging, they are very fragrant but above all they have a color that does not exist among the rustic ones: blue. Their countries of origin are Australia, the Far East, Africa, South America. In these countries they populate stagnant waters and slow-moving streams. The number of tropical water lily species is considerably higher than that of hardy water lilies. The flowers of all tropical water lilies rise about twenty centimeters above the surface of the water and are produced in large quantities. The leaves are larger and more decorative because they are often colored, veined with purple and serrated on the edges. In Northern Europe they are grown exclusively in heated greenhouses or winter gardens. Here they can be grown outside in the summer and protected in the winter months. The sacrifices that must be made in conserving these water lilies in the winter are largely offset by two unique characteristics: only among tropical water lilies there are varieties with blue flowers and some species bloom at night.
CARE AND MAINTENANCE
Most of these water lilies are bulbous plants and are relatively easy to cultivate provided, however, that some essential needs for their vegetation are met.
- the substrate must be rich in organic matter and composed of clayey earth mixed with sand.
- the bulb must be planted at a depth of no more than thirty centimeters.
- the water temperature must be at least twenty-five degrees. In the north of Italy this temperature is easily reached in June.
- tropical water lilies need a lot of light to develop; absolutely must be planted in the sun.
- it is necessary to limit the number of leaves to stimulate the plant to produce more flowers.
- the bulbs of these plants must be withdrawn before the autumn frosts. They can be stored in wet sand and stored in a room with an average temperature of ten degrees. If unfortunately the bulb is hit by frost, the water lily is lost.
- during the vegetative period they must be fertilized once a month with a slow release balanced fertilizer.
