Julles,
I believe you are the person who asked if the Koi mess in my plants in the pool to pond conversion. They try but I have gotten pretty good and winning the battle.
First, I plant in Kitty Litter so any mess does not promote algae growth and is easy to vacuum up.
Second, since my entire pond is 3' deep, my homemade PVC pipe stands regulate the height of my plants . My bog plants are only about 1/2" below the water and the Koi do not try to go up there much. My lilies are about 12" deep and I employ a number of tactics to win the war against the Koi corp,
who range in size from about 4-18".
I top my hardy lilie pots with good big flat river rock, about 8" size. I pile on several layers. Since I repot my hardies every year, the tenacious Koi are able to suck out some of the litter from any little holes in the coverage early in the season before the roots anchor it. Later in the season everything pretty much stays put and they aren't very happy about it. I use these rocks on the hardies & my 2 night bloomers because of the way they like to grow in all directions and I don't want to discourage this growth. My watergardeners group relies on these off-shoots for our big fundraising May plant sale.
Last summer I tried an experiment to protect my tropicals & it was very successful
. I got the thinest flagstone I could find; pieces that were pretty cheap. I made a template of the top shape/size of my pots. I cut this circle into quarters and then used a grinder with a diamond bit to cut the 4 quarters out of the flagstone. Then I cut off the "point " off each quarter. When laid over the kitty litter & around the lily tuber they covered it perfectly while leaving the hole in the middle for the tuber. The Koi could not move these flagstone slices and the cracks where the pieces abutted each other were close enough to keep the koi from sucking the litter through them.
Another benefit of my tropical flagstone covers was that it was really easy to lift the sections to put the fertilizer tabs in.... much easier than moving all the rocks from the hardies.
This years experiment I think will be another success. I use oil-pan shaped pails from the dollar store for my lilies. They are somewhat shallow but big around; a good shape for lilies. I do fertilize a lot and it is a pain to dig down in the kitty litter to get the 2 tabs i use every 3 weeks into the bottom of each lily pot. Last fall I repotted my tropicals for overwintering in a kiddie pool with aquarium heaters. Before I moved each lily into its new pot, I lined the pot with a piece of shade cloth cut to fit and to just stick up an inch over the side rim of the pot. Now, instead of digging down into the kitty litter to place the fertilizer tab, I can just lift the edge of the shade cloth liner and put the tab between it and the pot.
I can see that the roots will grow throw the shade cloth but that is fine. Shade cloth is tough and I expect it will last several years at least. I just want an easy way to access the bottom of the plant where I want the fertilizer tab. I think I will do that will all my plants that I fertilize a lot and plant in those wide shallow pots, like my cannas.
Hope that answers your question, Julles, and I would love to hear what others do to solve Koi & fertilizing problems.
Casey