I ordered this product recently: ISTA 4g Aquarium Cyanoacrylate Adhesive Aqua Plant Super Upgrade Instant Glue. It is VERY helpful in keeping my plants where I want them. I have some very wispy water sprite which is always getting uprooted when I barely bump it. I took a very small (1-3/4 inch) terra cotta pot that I got at the craft store and dabbed some of this glue on the inside rim. I then gently pressed a part of the water sprite plant (about an inch above the roots) to the glue on the inside rim and voila, the plant stayed put! I have also been experimenting with gluing plants to saucers and then burying the saucers in the substrate, leaving only the plant showing. Of course, you have to meet the plant's needs, i.e., not bury the crown for some plants, etc., but overall, I've been very happy with this product. Thought I'd give the heads up to anyone else who is always knocking their plants out of the substrate!