The boom in aquatic plant sales the last 10 years has brought a boom in aquatic pests. Water lilies, lotus and bog plants all have unique challenges with bugs and diseases but we can adopt the tried and true techniques of Integrated Pest Management (IPM) to start cutting down on problems.
Careful with plant selection. Check out new plants carefully before adding them to your water garden. Look for insects or unhealthy foliage or root systems. Make sure you rinse off new plants before putting them in your pond and consider repotting them in sterile media if you’d like to be extra cautious.
Don’t crowd your plants. Many homeowners come in to Mulkern Nursery wanting to purchase as many water lily varieties as possible – and I often talk them out of it. Water lilies are healthiest with three feet or more space in diameter for their leaf-span. Some plants, like night bloomers, do best with 5 or 6 feet. Crowding plants limits light and air circulation and can promote pests.
Consider sunlight available. Most water lilies need 6-8 hours of sun a day to do well. Make sure you place plants accordingly in your yard. Clean your water lily at least 1x week. Remove dead and sickly leaves from your plants regularly. Over flow the water pot or add fresh water to your pond. Remember to move your aquatic waste far away from your plants so pests don’t come back.
Create an ecosystem. Make sure you balance your water garden with different types of submerged grasses, floating cabbage and fish. Submerged plants and cabbage are natural filters and help keep water balanced. Guppies not only eat mosquitoes but also other nasty bugs that might have their eye on your water lilies.
Make sure your plants have enough food. Fertilize your plants at least every couple months. Also, repot your plants often to replenish essential nutrients in the soil. With smaller pots, I like to repot my water lilies twice a year.
Remember they go dormant! Even in Hawaii where our winters are characterized by shorter days and increased rainfall, that’s enough to trigger some water lily varieties to go dormant. This will look like: reduced number of or no leaves and all, and/or reduced number of or no flowers, and/or smaller leaves and flowers. If you think your plant has died, I recommend keeping it for a couple months and seeing if the change in season wakes it up.
Best of luck with your aquatic plants!