The Gardening Year for the Water Garden
Spring
In mid spring, clear out blanketweed from ponds and thin out oxygenating plants. Overcrowded bog and aquatic plants should be divided and re-potted. By late spring, bog, deep-water and moisture-loving plants and marginals may be planted out.
Summer
Throughout the summer, continue to clear blanketweed from ponds. Keep the water topped up and aerated - especially if the pond contains fish. Aquatic and marginal plants may be planted until mid-summer; deep-water plants until late summer.
In mid-summer, softwood cuttings of marginals and oxygenating plants may be taken for propagation. Seed may also be collected and sown under cover.
Autumn
In early autumn, divide established clumps of marginal and bog plants and thin oxygenating plants. Cut back any excess growth of waterside plants or submerged plants and remove any debris from the pond, including any decaying matter. Net the pond to protect against heavy leaf fall.
In mid-late autumn, move tender floating plants to a frost-free place. The end of the autumn is a good time to clean and service the water pump.
Winter
Prevent the pond from forming a solid layer of ice during the winter, as this will trap poisonous methane gas released by decaying vegetation. Before winter sets in, float an inflated ball on the surface of the water to keep the pond from freezing over entirely, or use a pool heater.