& Aquatic Plants
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There are a number of ways to fertilize your waterlilies and other aquatic plants and a number of products that you can use. The important thing is that you do feed them!
In the old days, well composted manure was mixed with heavy garden soil, the lilies planted and gardeners hoped the nutrients would last for the season. Today we have fertilizers designed especially for aquatics that greatly enhance plants' health and performance. Non-aquatic fertilizers can also be used with the results of some experienced growers below.
Rate of application and frequency will be determined by your soil type, water temperature, plant size, pot size and which fertilizer you use. We give one Pondtabb per gallon of soil (sand in our case) in the pot to a normal sized waterlily every four weeks when the water temperature is 60-70F, every three weeks when the temp is 70-80F and every two weeks when the temp is above 80F. Small plants get proportionally less and large plants are fed weekly.
Over the years we have done a number of side by side tests of fertilizers. When we first began growing waterlilies, the special aquatic tablets weren't available so we used Jobe's sticks (Beautiful Flowering Houseplants and Tomato formulations). These provided better results than no fertilizer but didn't dissolve very much. Weeks and months later they were still there, soft but there. We were happy to test Pondtabbs when they came available and Pondtabbs far outperformed Jobe's. Many growers, however, report excellent results with various Jobe's formulations.
There are several very hard tablets labeled for aquatics that don't dissolve at all so really don't feed at all. The best alternative to Pondtabbs that we have found is Highland Rim but they are expensive in comparison even though they are double the size of Pondtabbs. We also felt they gave more foliage than flowers but others have reported the opposite.
Please keep in mind that some of the big name fertilizer companies, hoping to capitalize on the boom in water gardening, have put new labels on existing fertilizers. They are designed for terrestrials, not aquatics. A few smaller companies have really devoted time to designing products just for aquatics and it shows in their performance. They are designed to begin breaking down in a matter of minutes, feeding almost immediately and are properly balanced for aquatics.
We have tried time release fertilizers and they give a first fast feed and then don't feed at all. Granular fertilizers are out for us since we plant in sand and they tend to burn the plants. Fertilizers made to be applied to terrestrials as liquids, when applied to aquatics in "burritos", dissipate too quickly to provide the plants much food.
With plants that can be difficult for us to grow we have had great success using a combination of Pondtabbs and the biostimulant cocktail we use on our Victorias. Details are here - Weakly Weekly.