How many oxygenating plants are needed for my pond?
Allow two bunches or portions of submerged oxygenating plants per square metre of surface area.
The deeper submerged oxygenating plants are often available for the longest part of the season as they are not so affected by the change in weather (Ceratophyllum demersum and Myriophyllum spicatum). They remain well below the ice level and continue working all through the winter.
Seasonal availability of submerged oxygenating plants:
Oxygenating plants which grow across the surface or send flowers onto the surface are often seasonal in availability – they have a peak period of growth and flower and then the weather no longer suits them and they fall dormant in the pond. They are not dead and will reappear next year (Potamogeton crispus and Ranunculus aquatilis).
These are only available bareroot when in active growth.
If they are ‘Currently unavailable’ when you choose your plant selection fill in ‘Email when available‘ and you will receive and email when they are available to purchase again.
We sometimes try to extend the selling period by rooting some of these into mesh baskets and compost to reinvigorate them into growth for a later part of the season.
Fool’s water cress (Rorippa nasturtium aquaticum) is different. It grows with leaf both above and below the water surface and is available for a large part of the season as its growth above water is not significantly damaged by frost and ice.
It is frequently off sale in high Summer when it sets seed. Your plant may appear dead at this stage but leave it in the pond and it will regrow leaf after a short recovery period.
Potamogeton crispus is very brittle as it gets older so is available for the shortest length of time before it becomes impossible to pick and bunch.
In your pond it is a good idea to have a selection of oxygenating plants so you have a variety of peaks in growth with one plant species or another being active at any given time.
If in doubt – add more submerged oxygenators to a new pond as the first winter can be a time when a lack of oxygen in the pond water will lead to wildlife deaths and it will take you some years to reach the ideal level of 30% volume full of submerged plant growth.
Leave as many oxygenating plants as possible in the pond through Winter and thin out in Spring if you still feel you have excess then.