Growing British Native plants from seed is easy.
Many British Native species of pond plants like Caltha palustris, Alisma plantago aquatica, Iris pseudacorus, Rorippa nasturtium aquaticum and Ranunculus flammula will seed down into the mud or the water and produce small plants for next year if you leave them to their own devices. A sure fired method of gaining extra plants for your pond and bog garden.
Collect seed now so you can sow seed in a greenhouse or cold frame and grow more plants in a controlled way.
Remove seedheads now if you do not want extra plants before they ripen and drop their seed naturally.
In the moist emergence zone British Native plants Primula veris, Lychnis flos cuculi and Succissa pratensis will set seed too. Tap the dried seedheads now and let the seed fall onto the soil and these new seedlings will come true.
Some non Native plants come true from seed too - Iris versicolor, Cyperus eragrostis but Named varieties of pond plants and bog garden plants should not be allowed to set seed. Seedlings will not produce the named variety but the parent plant so remove these seedheads. Propagate Named varieties by splitting the parent clump - vegetative propagation.