For flowering pond plants in April this year look at the Caltha family - the white flowerer (alba) expected first followed by the British Native Marsh Marigold and then the giant leaved Caltha palustris 'Stagnalis' burst into flower. Like the daffodils in the rest of the garden they shout 'Spring is here'
Then the Iris start to send up spiky leaf growth. The Variegated Iris pseudacorus looks fresh and bright at this time of year with yellow streaked foliage emerging above the water.
Oxygenating plants should be coming into growth soon but may still be quite deep in the water due to the current cold spell. It stays cold 2ft down in the water for a long time so Rorippa nasturtium aquaticum is a good early oxygenating plant as its leaves are only just below water surface. We have a choice of oxygenating plants available for sale already more varieties that will be available as soon as it warms up further.
Remember that the deeper the plants are submerged in the water the longer it will take the warmth of the sun to reach them so they will be later to respond and grow.
For that reason plants that raft on the water surface are growing best now - Myosotis scorpioides (Water Forget me not) is very good for the newts at this time of year. Newts also like the warm top inches of the pond water and will lay their eggs in its leaves as they are well formed and providing cover already.
Oenanthe javanica 'Flamingo' is starting to spread out too if you like a more colourful rafting foliage plant with small leaves.
For more advice on planting the marginal pond shelves with plants see our Tips and Advice pages.