The Critical Role of Pond Plants
Plants not only create visual interest with a variety of growth patterns and leaf structures, but many provide a profusion of beautiful, fragrant, colorful blooms. Pond plants attract a rich variety of wildlife, including pollinators like butterflies and dragonflies, and provide shelter or habitat for many more. If that weren’t enough to convince you to focus on their decorative value, pond plants also are key players in the effort to keep your pond healthy.
Nutrient Cycle - The Master Key
The nutrient cycle describes the natural process of nutrient uptake and subsequent release in aquatic environments. It’s a complex process that involves your carefully curated selection of pond plants and microscopic phytoplankton. These organisms create a food chain in a pond ecosystem, where plants absorb nutrients in the water to support photosynthesis, which provides energy for the plants to grow and spread. As plants are consumed by higher organisms in the food chain, the nutrients move up the food chain and support even more complex life forms. When these organisms die, their remains are broken down by beneficial bacteria, over several steps which release nutrients back into the water in a form that can be utilized by plants. In a healthy ecosystem, this cycle is balanced and robust with neither an overabundance nor a scarcity of nutrients.
When nutrients are out of balance
There’s a tight focus on the availability of nutrients in a pond because it’s a key influence and indicator of a pond’s health. Inadequate nutrients limit the growth of aquatic plants, which reduces the amount of food and cover available to creatures higher up the food chain. Malnourishment at the lowest levels of the food chain means all the higher organisms will suffer. On the other hand, an overabundance of nutrients can trigger overgrowth in prolific spreaders like phytoplankton, string algae and invasive plant species. A pond that’s been taken over by invasive plants or algae will suffer a spiraling breakdown of the ecosystem as the pond is shaded out, oxygen is depleted, anaerobic bacteria take over the process of breaking down biological waste and release toxic byproducts that further damage the health of plants and aquatic wildlife.
Key players
In a well-balanced ecosystem, a healthy plant population will take up the available nutrients as they’re released and maintain healthy growth. Rapid spreaders like algae will find there aren’t enough available nutrients in the pond to support their growth habits and will be unable to get established. With a diverse population of healthy pond plants, the local ecosystem is supported, the nutrient cycle is in balance, and nuisance algae is kept at bay.
Pond Plant Zones
Deep water/fully submerged plants
https://www.btlliners.com/best-oxygenating-plants-for-your-pond
Aquatic plants, whose entire structure, including leaves, is permanently submerged, are the most valuable plants for healthy pond water. These plants, do the most work in removing excess nutrients and keeping oxygen levels at a healthy level. Any body of water, no matter how large or small, that suffers from large areas of anoxic conditions (absence of oxygen) cannot support life beyond a limited variety of microscopic organisms and is well on its way to dying, a process known as eutrophication.
Submerged plants draw their nutrients directly from the water rather than soil, so while they can extend their anchoring roots directly into pond substrates like gravel, they can also remain in simple gravel-filled pots anchored to the bottom of the pond. Keep in mind that, while submerged plants live happily in deeper parts of a pond, they still need sunlight, so avoid extremely deep water and make sure they’re not shaded out by floating plants above them.
Understanding the role of submerged plants in maintaining healthy oxygen and nutrient levels in your pond should help as you decide what types and how many deep-water plants to include in your plan.
Floating plants
https://www.btlliners.com/best-floating-plants-for-your-pond
Besides taking up nutrients and shading out nuisance organisms like algae, floating plants help mitigate high water temperatures and limit evaporative water loss. They also provide pond residents with cover from birds and other surface predators. Frogs can sometimes be spotted resting on the floating leaves, on the lookout for insects drawn to pond water. Many floating plants, like water lilies and lotuses, are quite fragrant and feature showy flowers and dramatic floating leaves, a crowning glory to your decorative pond.
Marginal and emergent plants
https://www.btlliners.com/best-marginal-plants-for-your-pond
There is a tendency among pond aficionados and plant suppliers to use the terms ‘marginal’ and ‘emergent’ interchangeably when discussing pond plants. Worse, you’ll often find completely contradictory definitions used from site to site. Strictly speaking, while there are official morphological differences between the two types, there’s also a lot of overlap in their preferred growing conditions. So, rather than getting caught up in picky classifications, we’re going to describe some differences, then pretty much group them together. When you’re shopping for plants, focus on an individual specimen’s preferred depth and how tall it grows above the surface of the water.
Marginal and emergent plants all prefer to live along the margins of a pond, typically with roots that remain submerged in a few or several inches of water. Regardless, both types of plant have foliage and flowers that rise above the waterline. To accomplish that, there are two basic types of plant structure: some have delicate stems and leaves and tend to be relatively small. We would call these marginal types. They prefer to have their roots and crown completely submerged while their leaves and flowers are above water. Since this first group is typically relatively small, that means they grow best in shallow water, usually between 2” and 6” deep
Emergent plants in that zone are relatively tall and robust with sturdy stems and leaves. (These are also sometimes described as bog plants, just to add some confusion into the mix.) These taller plants with sturdier stems, however, are capable of living in a much broader range of pond edges, from bog-like permanently waterlogged (but not necessarily submerged) soil to water as deep as 16”. In fact, this is probably where the main source of confusion between marginal and emergent varieties arises: “marginal” plants actually prefer a relatively small sliver of the broader zone where “emergent” plants thrive. Either type would be happy to occupy those submerged plant shelves you’ve carefully carved out in your pond.
Regardless of whether you classify them as marginal or emergent, though, these are the most important specimens to include if you’re constructing a pond that should appeal to wildlife. These pond-edge plants provide important food, cover, and breeding grounds for pollinators and plenty of beneficial insects, as well as birds, small reptiles and amphibians.
Bog plants
https://www.btlliners.com/best-bog-plants-for-your-pond
Strictly speaking, bog plants are not aquatic plants, but they’re happier in wet conditions than most other plants and can even tolerate occasional flooding. This means they thrive in moist soil along the edges of ponds, lakes, and rivers. Like emergent plants, bog plants are invaluable in providing attractive and healthy habitats for wildlife. Keep in mind that many bog plants can be quite tall, so don’t plant them in a place where they can completely disrupt your view of the pond.
Choosing the Perfect Plants
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Having considered the size and location of your pond, as well as the roles your plants should fill (Oxygenator? Spring color? Habitat for tadpoles?), it’s time to look deeper before you make your selections.
Consider your pond throughout the seasons. Are you looking for plants that will survive through the winter? Even in regions where temperatures remain below zero for months at time, hardy lilies can survive in a dormant state in the bottom of a pond 3’ or deeper. Less hardy plants can be brought inside for the winter, but tender annuals will need to be replaced each spring with new, vibrant specimens—a great chance to try on a new color or texture palette! Always check hardiness zones before you purchase!
Opt for native species, if possible. Those will grow well in conditions where they’re already adapted, and they’ll provide important support for native wildlife who may struggle without their favorite food and shelter plants.
Always avoid plants classified as invasive in your region and don’t dig wild specimens from nearby ponds or streams - invasive plants outcompete natives and can reduce biodiversity, eliminate habitat, and severely damage the local ecosystem. If you elect to plant vigorous spreaders, even if they’re not classified as invasive, keep them in pots so they can’t grow out of control.
