Koi love pond plants. They especially love to eat pond plants. But, there’s hope. Here are a few of our favorite tricks for keeping koi and aquatic plants in your backyard pond. Whatever you try, remember that every koi is different. These tricks have fooled our koi, but that doesn’t mean they will fool your koi too.
Create a koi-free zone for your water plants. Use chicken wire or heavy plastic netting to fence off an area of your pond, creating a koi-free safe zone for your pond plants. Take time to ensure that there are no holes or weak points where your koi can slip through. For best results, allow the fencing material to extend above the water’s surface an inch or two. Finally, be careful to use heavy gauge netting or fencing — the fine bird netting could catch and tangle your fishes’ fins.
If you have the space, you can take this idea one step further, and actually construct a second pond for your plants. A small pond sited above your koi pond will keep your plants safely away from the koi, and will also give you the opportunity to incorporate a waterfall or stream into your backyard water garden.
Use floating plant baskets to protect delicate floating and oxygenating plants. Empty pond plant baskets will float right at the water’s surface, creating a floating barrier between your pond plants and the hungry koi. This is a great way to combine floating plants — water hyacinth, water lettuce, frogbit, water poppy — with koi. This technique also works for submerged and oxygenating plants, such as anacharis, parrot’s feather or bacopa. Take care: aggressive koi may figure out how to tip the baskets, and water falls or fountains could flip the baskets too.
Grow koi safe pond plants. Koi will eat almost anything, but thick-stemmed water plants are generally pretty safe. Lotus, umbrella palm, cattail and other sturdy reeds and rushes can often withstand their hungry assaults. Less-aggessive koi may even let you grow water lilies. Some koi will dig up pond plant roots, so you may want to protect your plants by covering their pots with thick wire or heavy stones.