I have often commented that one of the major reasons, if not the single biggest reason, for failure in growing plants is forgetting to water them. There are ways around it, putting in irrigation systems, for example, or having timely reminders from people like me. But ultimately, if plants don’t get water, they don’t grow, but equally, if they get too much water, many plants will die of waterlogged roots.
Of course there are plants quite at home completely submerged in water. Plants originally developed in the oceans of the world, where they had no concern about water supplies, and had a completely different set of problems. Most of the useful water plants you might wish to grow are actually land plants that appear to have re-adapted to the aquatic lifestyle, but they all tolerate, and even thrive, sitting in a body of water.
One of my favourites is Vietnamese or Hot Mint (Persicaria odorata) which I have been growing for years. I originally started growing from a stem I took home wrapped in a moistened serviette from a Vietnamese restaurant. It’s still going, and I have divided and given out dozens of plants from that original stem. But I learnt the trick to keeping it alive is to have its pot sitting in water all the time. I first kept it in pot, in a bucket, then graduated to a “pond” which is actually an old deep shower base I found on the side of the road.
I have grown other things in my shower pond, including Water Chestnuts (Eleocharis dulcis), which I had planted in a large, flat basket so they could be lifted out easily for harvest. At the moment I have Kang Kong (Ipomoea aquatica) a relative of the Morning Glory Vine, which is used for its abundant leaves, Taro (Colocasia esculenta) which is grown for its tubers, stems and leaves, and so-called Fool’s Watercress (Apium nodiflorum) which is a kind of perennial edible plant closely related to Celery (A. graveolens).
I have also thrown in Duckweed (Lemna minor) and the native water fern Azolla (Azolla pinnata) which help soak up excess nutrients in the water, as well as shade it. They float on the surface, grow really fast, and can be scooped out and used as mulch in other parts of the garden to keep the nutrients cycling. The only real drawback in having standing water is that you will attract mosquitoes to your garden, and they will lay eggs in the water, and while I don’t personally seem to get bitten much, it’s not the most pleasant of things if you wish to spend time out there.
Some people recommend putting oil or kerosene on your pond to counter the little wrigglers. I would never use anything like that, especially when growing food plants in the pond. The best thing to do is get a couple of fish who will eat he larvae. Goldfish are not that great, but better than nothing, ask a local aquarium what they suggest, it will depend on where you live. Also, they tend to like stagnant water, so a little fountain or waterfall pump might just do the trick, a solar powered one would be ideal.
While it may be starting to cool down, it might be worth thinking about planning for the spring time, and certainly while plans are dormant is the best time to set them up for next year. And don’t think the plants I have mentioned are the only options, there are a heap more plants that will grow in a small pond, and anything that can hold water is a suitable container. I just pot the plants in ordinary potting mix (regular grade Australian Standard, of course) and plonk them in the water. Simple as that!