What’s the Difference and Do You Need Both?

When choosing oxygenating plants for a pond, one of the most common questions is whether to use bunched oxygenators or potted oxygenators. They’re often talked about as if they’re interchangeable, but while they ultimately do the same job, they do it in very different ways. Understanding that difference makes it much easier to plant with confidence and build a pond that stays balanced over time.

What’s the Difference Between Bunched and Potted Oxygenators?

The short answer is that bunched and potted oxygenators do the same job, but in different ways. Both help oxygenate the water and reduce the nutrients that feed algae, but they work in different parts of the pond and on different timescales.

Bunched oxygenators are loose, fully submerged stems that interact mainly with the water column. They take nutrients directly from the water and tend to respond quickly when conditions change. Potted oxygenators are anchored plants that work through roots or rhizomes, drawing nutrients more slowly from the pond base and helping to stabilise the system over the long term. Rather than one being better than the other, they complement each other.

Starwort, a bunched oxygenator with leaves perfect for newt eggs, and Dwarf Hairgrass, a fine stemmed potted oxygenator for a soft pond meadow.

How Bunched Oxygenators Work

Bunched oxygenators are sold as loose stems held together with a small leaded weight. That weight isn’t just to stop them floating away, it helps the stems sink to the bottom of the pond so they can settle into position.

Most bunched oxys are fully submerged plants that absorb nutrients directly from the surrounding water. This makes them particularly effective at competing with algae, especially in spring and early summer when nutrient levels can rise quickly. Some species will form roots once they come into contact with gravel or natural sediment, while others anchor more loosely or remain completely rootless.

Many bunched oxygenators also reproduce using stem fragments or by forming overwintering buds, known as turions, which rest in the pond base during winter and regrow when conditions improve. This is one reason heavy winter “clean-outs” can be counterproductive, removing all the material from the bottom of the pond can mean removing next season’s plants before they have a chance to return.

How Potted Oxygenators Work

Potted oxygenators behave very differently. These plants are grown in aquatic baskets and rely on roots or creeping rhizomes rather than loose stems. Instead of reacting quickly to changes in the water column, they provide steady, long-term support by stabilising sediment and drawing nutrients up from the pond base.

Some form soft underwater meadows, others grow as upright submerged plants and some spread gently across shelves, knitting the pond together. Because they are anchored, potted oxys tend to be more predictable in where they grow and how they spread. They don’t usually give instant results, but over time they create a more resilient pond that is less prone to sudden swings in water quality.

Do You Need Both?

In many ponds, the answer is yes.

Bunched oxygenators act quickly, mopping up nutrients in the water and providing immediate underwater cover. Potted oxygenators work more slowly but create structure and stability that lasts from year to year. Used together, they mirror how natural ponds function, with fast responders above and steady support below.

Why More Plants Means Less Algae

Algae and aquatic plants are competing for exactly the same nutrients, mainly nitrogen and phosphorus. The difference is speed. Many common pond algae can double their biomass in just one to two days under favourable conditions, particularly in spring when light levels rise but pond plants are still dormant or slow to grow. If there aren’t enough plants in place to use those nutrients, algae will always step in first and out-compete them.

Underplanting is one of the most common causes of green water and blanket weed. Oxygenators are not decorative extras; they are working plants. The more leaf surface you have in the water, the more nutrients are locked into plant growth rather than feeding algae. The aim isn’t to create a jungle overnight, but to give the pond enough plant mass to stay ahead of nutrient build-up. In most cases, problems arise not because there are too many plants, but because there are too few doing the right jobs.

Mare’s Tail, a potted oxygenator with upright architectural stems, and Hornwort, a free floating oxygenator ideal for wildlife cover.

Why Pond Ecosystems Like Variety

A pond planted with only one type of oxygenator is like a town made up of identical houses, it might look orderly, but it doesn’t suit everyone.

Different plants offer different structures and functions. Soft-leaved plants are used by newts for egg laying. Dense stems provide shelter for tadpoles. Low meadow plants stabilise the pond base and support invertebrates. Upright plants add vertical structure and seasonal interest. No single plant can do all of this on its own.

Wildlife responds to this variety and so does water quality. Layering plants from the pond base, through mid-water, up towards the surface creates a far more resilient ecosystem than relying on a single growth form.

How Much Do I Need?

This is where it’s important not to underplant. Oxygenators are the engine of your pond, they keep the ecosystem clean and operating well.

For bunched oxygenators, allow 2 to 3 bunches per square metre. This provides enough plant mass to compete effectively with algae without overcrowding the pond.

Potted oxygenators should be planted as part of your marginal scheme, using 5 × 1-litre plants per square metre, or 3 × 2-litre plants per square metre. Always check planting depths and match plants to your pond shelves, as different species prefer different water levels.

Our Simple Guide to Choosing Oxygenators

For still ponds, a mix of bunched oxygenators and potted meadow-forming plants helps balance fast nutrient uptake with long-term stability. Bunched plants such as Water Crowfoot and Hornwort work actively in the water column, while rooted meadow plants help stabilise the pond base and build resilience over time.

For moving water, such as streams, waterfalls, and strong pump returns, plants adapted to flow perform best. Willow Moss is particularly well suited here, where it can be tucked into gaps between rocks and kept fully submerged, gripping hard surfaces rather than trying to root into soil.

For a natural wildlife pond, meadow-style potted plants such as Dwarf Hairgrass and Pepper Grass help knit together the pond base, support invertebrates, and create excellent underwater habitat, especially when combined with bunched oxygenators such as Hornwort, which provides additional mid-water cover.

For newt-friendly ponds, Starwort is especially valuable. Its fine leaves are used by newts for egg laying, and its dense growth provides shelter and feeding areas for larvae and tadpoles. Because it grows quickly in UK conditions, it works best as part of a mixed planting rather than on its own.

If you enjoy a wilder, more natural look, upright plants such as Mare’s Tail add structure and seasonal character, rising above the water surface while still contributing submerged growth below. They bring height, texture, and a sense of movement to the pond.