Frogs are a wonderful addition to a garden; they help to control potential pests such as slugs and snails, and also support predators such as birds and snakes, which in turn help to control mice and rats. The frog is also a bioindicator, meaning that when it is present, the ecosystem is healthy.
Encouraging frogs into gardens can be done by selecting plants that meet their needs for clean, oxygenated water, plenty of cover, and an abundance of invertebrate prey on which to feed. This includes both aquatic and terrestrial plants, which can support a whole host of life aside from amphibious species.
1) Coontail (Ceratophyllum demersum)
Coontail, also known as hornwort, is a free-floating aquatic plant that does not have roots. It branches and forms large underwater masses, which provide a hiding place for invertebrates – this is of enormous benefit to frogs, as they are provided with a reliable food source. This plant is also fantastic at decontaminating water, absorbing substances such as copper and zinc.
Ceratophyllum demersum does best at a pH between 6 – 7.5 and prefers temperatures between 16 – 29°C (61 – 84°F). It requires plenty of space to grow, so is best suited to larger ponds and needs a good supply of sunlight. This plant does not do well with high levels of nitrites or nitrates, so introducing a nitrogen-fixing plant such as duckweed may be of benefit.
2) Common duckweed (Lemna minor)
Species of the family Lemnaceae are the smallest flowering plants known. Duckweed, Lemna minor, belongs to this family and has tiny oval-shaped leaves which grow to just 0.8 cm (0.3 in) in length. The flowers are even smaller, reaching just 0.1 cm (0.04 in) in width, and are white in color.
In calm waters with little current, duckweed will grow rapidly. It thrives in sunny locations, and while it is adaptable in terms of temperature, it grows best between 17 – 26°C (63 – 79°F). Lemna minor is a nitrogen-fixing species that can be used for water treatment. As well as improving ecosystem health, it provides a hiding place for tadpoles, and frogs have also been reported to eat it.
3) White water lily (Nymphaea odorata)
The white water lily is hard to miss – with its circular floating leaves that can reach up to 30 cm (12 in) in diameter, and its large white flowers with numerous pointed petals. This species is native to the northeastern United States, where it can be found in calm, quiet waters. If planting water lilies, take care that they do not expand and cover the entire surface of the water, as this can have a detrimental effect on other organisms.
Nymphaea odorata fulfills a number of important functions in aquatic environments: it oxygenates the water, creating a suitable habitat for tadpoles, and its leaves provide hiding places for adult frogs. Some species will also perch on the lily pads – this can provide an easy escape route from predators such as aquatic snakes.
4) Plantain lily (Hosta spp.)
There are various types of plantain lilies, commonly known as hostas. These plants are native to Asia but have been widely introduced into gardens across the world, as they are attractive and easy to grow. They have ribbed leaves which can be green, blue, yellow, or even variegated, and grow well in shady areas with moist soil.
Hostas are highly attractive to slugs and snails; thus, they host a valuable food source for frogs, whose presence is often welcomed by gardeners wishing to reduce the number of these pests. Another reason frogs may gravitate towards hostas is that their foliage provides cover and protection from predators.
5) Horsetails (Equisetum spp.)
There are around thirty different species of horsetail, often referred to as scouring rushes. These plants have deep roots and can become a problem if allowed to spread too much, so should be planted with caution. They are fairly adaptable in terms of habitat, however moist soil and plenty of sunlight are a must.
Frogs are drawn to horsetail, often using it as cover to escape when threatened. Treefrogs have also been observed climbing horsetail stems in stormy weather, in anticipation of mating. Not only do horsetails provide a habitat for frogs, but they also support a diversity of life in the soil; their stems provide structure, and the decay of dead plants provides a vital food source for microorganisms.
6) Blue flag iris (Iris versicolor)
The blue flag iris grows to 60 – 90 cm (24 – 35 in) in height, and has slender, pointed leaves and violet-blue flowers. Its preferred growing conditions include slightly acidic soil that is moist or wet, and full sunlight, without which it may fail to flower. Once established, it can easily spread via rhizomes and self-seeding.
This species provides cover at the edges of ponds, providing a means for frogs to safely enter and exit the water. It also offers shelter to newly hatched tadpoles, protecting them from predators.
7) Water violet (Hottonia palustris)
The water violet is classified as a submerged plant because while the flower stem (which can grow up to 80 cm (31 in) tall) protrudes from the water, the stem and leaves remain under the surface. The flowers are white with a yellow center. Hottonia palustris provides several ecological benefits that can encourage frogs to use ponds: they oxygenate the water, remove excess nutrients such as nitrogen and phosphorous, and provide shade from the sunlight.
Water violets grow best in partial shade and are suited to water between 5 – 80 cm (2 – 31 in) deep. They are quite sensitive plants and are vulnerable to drought, water pollution, and increased salinity.
8) Amazon frogbit (Limnobium laevigatum)
Amazon frogbit is adaptable and capable of thriving in a variety of habitats. It has circular, bright green leaves which float on the surface of the water, while its roots are long and covered in thousands of tiny hairs – these hang vertically in the water. This plant thrives in warm conditions with plenty of light.
As well as providing cover for frogs when they are underwater, the Amazon frogbit’s roots act as oxygenators, improving ecosystem health. This plant also removes excess nutrients such as nitrates from the water, meaning that other organisms can thrive – providing frogs with a source of food.
9) Spiked water-milfoil (Myriophyllum spicatum)
Spiked water-milfoil is an invasive species in the United States, and can cause serious problems for aquatic ecosystems if left uncontrolled. However, when carefully managed, it makes an attractive addition to a pond. Due to its oxygenating properties, it helps slow the spread of algae and makes the water more habitable for organisms such as frogs and their invertebrate prey.
Myriophyllum spicatum is an adaptable species that can grow in a great variety of conditions; however, it does have a preference for clear water with plenty of sunlight. This plant requires very little care, but it should be kept in check by regularly trimming new shoots.
10) Wildflowers
A wildflower meadow can present a number of benefits to frogs. The plants within a meadow provide cover and often retain moisture, creating a damp environment in which the frogs can forage. The provision of nectar from flowers also encourages a variety of insects, some of which frogs can feed on.
The specific species of wildflowers that work best depend on the climate, however, some common ones include black-eyed Susan, blue vervain, butterfly weed, and cardinal flower. Treefrogs can sometimes be found resting on black-eyed Susans.
11) Mare’s tail (Hippuris spp.)
Mare’s tail is an aquatic plant native to North America. It typically grows in shallow water or on muddy banks, protruding out of the water, and it spreads very easily via creeping rhizomes. This species prefers cooler waters and alkaline conditions. Once established it is very difficult to remove, as it is able to regenerate from fragments of a plant – care should be taken to keep mare’s tail under control.
Despite its reputation as a problematic plant species, mare’s tail does provide a good habitat for spawning frogs, as well as encouraging a diverse range of invertebrates, which provide a vital food source. It is also an oxygenator, thus contributing to the health of aquatic ecosystems.
12) Swamp milkweed (Asclepias incarnata)
Swamp milkweed is a tall perennial plant that thrives in sunny swamps and marshes, although it can also be introduced to the edges of ponds. This plant has narrow leaves with pointed tips and produces pink flowers. Asclepia incarnata grows best in wet, clay soil, although it can also survive in less favorable conditions.
This species provides cover for frogs, keeping them moist and out of sight of aerial predators. In addition, it attracts insects such as Monarch caterpillars, which frogs can feed on despite their toxicity.
