Plants for a wildlife pond

Plants are the structure of a wildlife pond: cover under the water, stems to climb out on, leaves to sit on, and flowers at the edge. The RHS says mid-spring to early summer is the time to plant, once the water has warmed.

Four jobs, with RHS examples

The wildlife pond guide sorts plants by what animals use them for:

1. Underwater cover. Hornwort (Ceratophyllum demersum) and water starwort (Callitriche autumnalis) give tadpoles somewhere to hide. These are the oxygenators people mean when they talk about "weed", and a wildlife pond wants a maze of them. You do not need a clear view to the bottom.
2. Tall stems. Damselfly and dragonfly larvae crawl up stems to leave the water. The RHS gives water iris (Iris ensata) as an example.
3. Floating leaves. Waterlilies (Nymphaea) and water hawthorn (Aponogeton distachyos) are resting spots, and they shade the water. The June pond notes suggest shading about a third to a half of the surface with waterlilies if algae is the problem.
4. Marginal flowers. Lesser spearwort (Ranunculus flammula), flowering rush (Butomus umbellatus) and marsh marigold (Caltha palustris) are the RHS examples for the damp edge, where bees and hoverflies turn up.

Native plants are the reliable default. The RHS also says many non-natives are fine, but some aquatics are vigorous in a small pond. Check the size before you buy.

Invasive plants are a real constraint

The RHS tells you to avoid known invasive aquatic weeds, and not to move plants, spawn or mud between ponds. That is how problems such as New Zealand pygmyweed spread. If you are unsure of a plant in a neighbour's pond, do not take a cutting. Buy named plants, or let the pond colonise.

How they go in

The RHS says most pond plants are best in aquatic baskets with a loam-based or aquatic compost, not ordinary multipurpose compost, which clouds the water and feeds algae. On a steep edge, the same guide mentions coir logs pre-planted with soft rush, purple loosestrife or yellow flag, and planting pouches hooked over a formal rim and held with a stone.

Yellow flag (Iris pseudacorus) is a native the RHS suggests for coir rolls. It is also a strong grower. Give it a basket if the pond is small.

Cutting back

Leave faded marginals until late winter if you can. The RHS says that gives invertebrates cover. If you do pull weed out, do not take most of it at once. Leave what you remove on the bank overnight so animals can crawl back. The care page says the same for summer blanketweed. Rinsing the pile in a bucket of pond water helps the smaller creatures.

A wildlife pond does not need a filter to "keep the plants happy". Fish food and fish waste are what the filter is for. See how to build the pond.

How much of the surface should plants cover?

The RHS June notes suggest a third to a half in waterlily cover if you are trying to reduce algae. A wildlife pond can have more open water or less. The animals use the planted parts. You do not need a mirror of open water in the middle.

Can I use garden soil in the baskets?

Use aquatic or loam-based compost, which is what the RHS specifies. Garden soil and multipurpose compost add nutrients the algae will use first.