Continue to plant up bog gardens. Tidy and mulch with composted bark or garden compost.
Thin out, cut back or divide excessive new growth on established aquatic plants. You can still plant new aquatic plants this month. Plant vigorous specimens in aquatic plant baskets to contain them. Top the surface with a layer of gravel to prevent the fish from stirring up the compost.
Begin stocking ponds with fish once new plantings have established. Avoid introducing goldfish to wildlife ponds. They will eat frogspawn and so upset the natural balance.
Troubleshooting
Remove blanket weed by twirling around a rough stick. Skim off floating weeds such as duckweed with a net. Leave weeds on the pond side for 24 hours to allow trapped creatures to return to the water before adding to the compost heap.