Alys Fowler: Edible Pond Plants for the Tiniest Puddle

‘Arrowheads seem to thrive in the somewhat boggy conditions. Another edible plant worth trying is water spinach’I have a tiny pond on my allotment, it is more akin to a puddle or a pothole. Despite its laughable size, it functions well for wildlife and even doubles up as space to grow food for me.In it I grow arrowheads (Sagittaria latifolia) that seem to thrive in the somewhat boggy conditions. Arrowheads (also known as duck potatoes or wapato; pictured) are aquatic herbaceous perennials from North America. Its tubers are about the size of a large chestnut and when boiled and peeled taste somewhat like a floury, nutty potato. You can also roast them.They don’t grow particularly big, so they are never going to make up a substantial part of your diet, but then again when your pond is the size of a puddle or a bucket (they grow very well in containers) I think that is obvious. Getting hold of tubers is not easy, though they do appear in aquatic nurseries, such as Devon Pond Plants.The tubers need to be buried in 10cm or so of soil, covered with at least 15cm of water. The pretty arrowhead leaves appear in spring, often followed by star-shaped white flowers. The plant dies back by late summer, at which point the tubers are ready to harvest.For ease of harvesting, grow in buckets or other containers suitable for holding water. For larger ponds, grow in aquatic baskets. I’ve found that just trying to shove the tubers into pond soil means that they all constantly float to the top. Ducks love them, hence the name duck potatoes, so if you have lots of ducks and want lots of tubers you may have to fashion some sort of protection.Another edible pond plant worth trying is water spinach (Ipomea aquatica, sometimes sold as water morning glory). You can easily find this in any Asian supermarket; it has long, round stems and spinach-like growth at the top. Buy a bunch and stick a few stems in a vase or a pint glass and eat the rest. After a week or two these will have rooted. Now you can transplant it into soil (use aquatic potting compost). It’s known as an emergent floater, so it will need at least 20cm of water to grow in. Alternatively, you can grow it from seed, sourced from Nicky’s Nursery.Water spinach hails from south-east Asia, where it is a staple crop. It needs warm conditions to thrive and won’t stand many nights under 10C. Growing it outside is always a gamble, though I have had success using an old aquarium in a sunny, sheltered corner. If you have space in your conservatory/polytunnel/greenhouse then you can get a decent harvest from even a large tub trug. It’s not cheap to buy from the supermarket so even a meagre harvest is worthwhile.• Follow Alys on Twitter
Arrowheads are aquatic herbaceous perennials from North American. Photograph: Linda Freshwaters Arndt/Alamy