>> 'overwatering' anything (which is really suffocation, lack of oxygen. Few plants actually enjoy/appreciate drying out, but with many "potting soils" drying is necessary so roots don't rot.)
I wish I had read that 3-4 years ago! And thank you for enjoying the "bottom-watering mat" article. Lots of companies sell widgets that support seedling trays up above a watering tray, and the wicking mat pulls up just enough water to keep everything happy.
But I wouldn't be happy just BUYing something that someone else made, even if it let me go away for a week with seedlings growing.
First I had to try bottom-watering in my bathtub. Not only did it not work well, I plugged up the drain halfway to the sewer and had to pay a plumber to unclog it before I could shower, flush, or use a sink.
Then I tried bottom-watering right in a tray with shallow flooding, then removing water with a turkey baster. Not only does that require hours of patient basting to remove the water, it assures flooding and perched water of the bottom inch or so. Drowned roots, BZZZZT.
I'm still looking for some thrift shop thingy that would provide a flat but draining, elevated but stable way to hold a tray up a few inches above my 1020 tray. Whatever!
Somehow something suppressed my Rube Goldberg gene for long enough to drop a cotton flannel pad in a tray, put the seedling tray on top of the pad, and add about a half-cup of water.
The grooves in the 1020 tray were like some genius had engineered them to be a micro-reservoir, and simplicity won the day. Despite my gadgety inclinations.
What was really cool about it was serendipitous. The flannel not only carries water TO each cell uniformly. It also draws water back OUT of a cell if you over-water it from the top (which I just HAVE to do periodically, as if it were some Gardener's Curse that I can't escape). But now it draws the excess water OUT, even including perched water, as long as I keep the water level in the tray below the top of the fuzzy mat.
Translation: I water until the mat is pretty damp, but I don't see any water.
Then, double-serendipitously, I tried over-watering only SOME of the rows in my tray. The mat pulled the excess water out of those rows, and
shared it with the thirsty rows!
The mat insists on being uniformly damp or dry everywhere, which makes the bottom layer of each cell uniformly damp.
The third serendipitous thing is that I don't have to guess whether the deeper parts of each cell are dry or moist. The bottom layer of each cell is about as wet as the mat! So I don't need to worry about keeping the soil from drying all the way out. I only need to keep the
mat from drying all the way out!
I can't take credit for figuring most of that out. Some brain-fluke just made me try dropping a pad between the water tray and the seedling tray, then watering lightly instead of flooding it. So easy that even I could do it. And maybe a spouse or neighbor could follow directions if you were away for a week.
It just turned out to solve multiple problems all at once.
