>> for small cells what you need to worry about is wicking too much water, not the other way around. so just using acrylic felt should be fine.
Thanks for pointing that out. I've had such a coarse mix that it probably doesn't wick enough for me to have seen that. When and If I go back to a seedling mix that wicks more, I'll watch out. I "should" use a better-wicking mix if I try to bottom water.
What I've done up to now has been to lay cotton flannel felt on the bottom of a no-holes 10-20 tray with "channels" and then set the insert trays or plug trays on top of the flannel. I never allow standing water to be visible. It just sits in the grooves and soaks the flannel. My goal is to keep the flannel a little damper than I want the soil mix, but I THINK my coarse mix doesn't wick enough to keep the top of the cells damp enough. So I "mulch" it and also top-water a little once or twice per week.
>> coir matting provides better aeration
I believe it! I have to screen all the fines out of bark when it comes from a bag of "mulch" or it would mat down and leave little air space. "Mulch" at HD is filthy stuff, usually full of dust and powder and even twigs pebbles and dirt. Log yard trash!
Then I went over to buying fine pine bark "nuggets" from Lowes - which are too coarse, but at least they have little or no powder. I mix in enough fines to make the nuggets wick almost enough. I think the result is 60% air, with lots of LARGE channels that can't clog with capillary water.
The best bark I ever found was $8 per 2 cubic foot and mostly chips and shreds (longer than they are wide or thick).
I tried bulk coir around 4 times. Every brick I bought had totally different texture: powder, chunks, a mix of everything, and just once, the kind of coir fibers I wanted. I finally gave up before finding a reliable source.
I was influenced by an Internet article claiming to have found enough salt in at least one batch of commercial coir to salt-burn seedlings. Maybe that was published by "the Peat Council of America", I don't know.
But coir matting sounds very promising. It would HAVE to be fibrous. I love the idea of preventing root circling by air pruning! Do I understand right that you wrap matting around the inside of a big pot, then fill it with soil? And the matting lets enough air in and humidity out that roots stop before they reach the plastic pot wall itself?
>> -peat ... needs to be cut with 50% perlite. but consider coir peat instead:
Actually I use "fine" bark nuggets to cut a peat-based commercial mix that imitates Pro-Mix.
I "cut" 20-30% of the commercial mix with 70-80% bark of various sizes. So it's more like "seasoning" screened bark with a little fluffy peaty mix to help it wick. (It's also around 1/4 the cost of all-commercial mix.)
For some reason I don't like Perlite - it looks like I'm growing pot. I will look for coir peat ... is there a brand name you favor? The idea of excess salt really turned me off.
>> i am an underwaterer - when i start DOTING on plants, then i better watch out...things get wetter and worse off
I agree totally, but have not yet been able to refrain from pampering plants to death. That's why I use a mix that drains SO fast that it's physically impossible to overwater.
I've only been bottom-watering for two years, so it may sink in someday how to avoid over-watering. Gardening has taught me that I'm incredibly resistant to change once I think of something as "my way". It was humbling! I thought I had an open mind and loved to try new things.
>> i find no need to flush often, i've never had problems with salts
I haven't actually had a PROBLEM with salts since the 1980s. I don't fertilize my seedlings at all, usually. I just have a paranoia that if I don't flush every plant in a container at least weekly, the boogeyman Salt gonna get 'em.
For some reason that seems most important when I'm first sowing seeds or potting up.
Probably the unconscious memory that drives me there comes from planting bushes or shrubs. I think THEY need to have their root ball saturated to settle the soil and ease the transition into the ground.
The rules "MIGHT" be different for planting tiny seeds in a 128-cell propagation tray, and for transplanting shrubbery. But try to tell my subconscious that!
>> -Salt built up in a crust on the surface
>> if you use mulch - you can just replace it and you're done!
True, I used to scrape that nasty crust off and throw it away. But I was so ignorant back in the 1980s that it amazes me today. I don't know how those plants survived what must have been nearly anaerobic soil! Now, I think I "know better" about many things, but still have some bad habits that I can't seem to shake.
