I cannot say much about this topic just yet, because I’ve only used trays for one application, so far. It’s not to say I cannot discuss my experience with using them, because I will.
I’ve used trays for easier hydration for my plants, but just know I use this method for a handful of plant varieties, not just carnivorous plants.
I know that the humidity tray method is often used, especially when the humidity is somewhat low around the plants. This involves trays filled with water and little rocks, pebbles, or gravel. Some are quite similar to aquarium pebbles or gravel; but it’s not to say that they cannot be used in place of these little rocks, pebbles, or gravel, because that’s what I’m using currently.
Trays can be used for a multitude of uses. Some are used for propagation, and some are used for long periods of hydration so that it’s not needed to constantly or frequently watering the plants.
In using these trays for watering plants, they obviously water from the bottom, which means that the top won’t be included in this process. This means, that it will require a top watering, or a spraying, to get the tops of the plants watered, which is fine, because whatever doesn’t touch the plants, will end up in the trays instead.
Some trays are meant for more than just holding water. Some may be used for other purposes, such as propagation, seeding, and just for keeping plants organized in a neat setup.
This is what you see with trays where people are seeding, and use them to space out their seeds for them to grow without being clustered and the roots potentially wrapping around other roots of other seeds beginning to root in that area. If it’s one or two, it’s not that big of a deal, but if it’s maybe five or more, then it can be an issue, if they are growing into separate plants. Which is why this can be a good solution to prevent that.
Some trays can be used for propagations, and growing moss. When looking at the process of growing microgreens, it’s not much different on the surface as growing live moss. (There may be more to this, so when I do find out, I’ll discuss it later.) Just have them in water, and have the tray covered. The tray can be one that has some partition between the outer tray and the plants intended for growth, where the water will go to the bottom of the tray, and hydrate and nourish the plants from the bottom. The top will be receiving any air and while covered, it will get the water evaporating and rising to the lid, and comes down on the tops of the plants. This way everything gets hydrated, but also humidity to accelerate that growth, which you see happen with plants in terrariums. For those that have holes in the lids, that’s for some of the air to escape, and eventually some of that moisture will also escape. Now, this will result in needing to refill the trays more often, but it’s good for preventing algae growth.
This isn’t a topic that I know much about. I’m still learning about topics like microgreens, and even growing live moss. The latter, I’ve tried, and it’s still in progress.
There are various uses for trays, besides organizing. When it comes to plants, you know of some, and other creative ways to make things better. Over time, I’ll find out more, to show you what I find.