Correctly made and correctly mixed, 5-1-1 shouldn't water log right off the bat, although it can seem to stay 'moist' for a long time for indoor plants. Outside during summertime, 5-1-1 should be pretty darn dry..at least thru the root zone...if you were to withhold water for say a week.

After a year or two, 5-1-1 can get a little mushy at the bottom depending on how much you water.

Seems like you jumped in with both feet. Folks new to 5-1-1 and Gritty may want to make up a small batch, plant a sacrificial plant and just get the hang of how the ingredients work together, as well as the routine of watering/drainage.

-Did you add lime?
-Did you add fertilizer in the mix or do you plan to use liquid? Don't wait more than a few days to give a very diluted shot of liquid fert.
-Are you making sure the water that comes out the drainage holes can in no way reestablish contact with the soil mix back up through the holes?

To answer your questions:

Didn't add lime as I want an acid pH.
Added Osmocote time released fertilizer
The holes were not blocked

The one container I had the problem with I know I watered the dry mix. I have to think that this caused the moss to migrate to the bottom and seal off the window screen. The pot was completely sealed, holding water, even when I removed 80% of the mix. Therefore, the problem was at the bottom, and was related to the moss sealing things off. That I why I was wondering if there is a better alternative to using sphagnum moss.

When I re-potted, I left the mix dry until I finished. Now everything seems to be OK.

Yes, I think you're right, you probably had a fine particulate layer at the bottom.

I make my 5-1-1 with a portion of potting mix (peat-based) instead of straight peat. It's a little more expensive, but it seems to work very well and bind the ingredients nicely.

I have also used pumice, lava rock (scoria), turface, and grit to make a more durable type of 5-1-1.

Josh

Good catch Seysonn on the math. Helps to explain the problems I had.

I was just going with what Al had for a big batch, which was 2-3 cf bark, 5 gal perlite and 5 gal moss. Maybe the recipe should indicate that one should adjust the amount of perlite and moss to the size of the bark bag.

Next time I do plan on using less moss, and possibly using a high quality planter mix instead of moss for water retention.

I really prefer a quality potting mix, as well. I've been substituting Ocean Forest potting mix for the peat portion of the 5-1-1, and I've had consistent and excellent results. Great texture to the finished mix, easy to wet, easy to work.

Josh

Josh, does a handful of Ocean Forest look like a handful of plain peat? Are there any hard particles like Perlite in there? I went to the website and it just said "Composted forest humus, sandy loam, and sphagnum peat moss"

Sounds like it would be major pudding if used alone.

It has Perlite, but not much. It's basically a loose peat-based mix with small particulate. I've never used it by itself, and I wouldn't - at the very least I would amend it with copious Perlite. But I really like it for that one part of peat in the 5-1-1.

It's also very expensive. I can't imagine how much it would cost to fill a container....or fifteen.

Josh

The problem is the screen, not the mix. A 3-1-1 mix is a decent mix. Try using dry wall mesh tape, it has bigger holes. The electo-static charge of the metal attracted the peat to stick to it, and also water will tend to stay on the screen too. Surface tension will hold it there. Non-metal with bigger holle like drywall tape solves the problem. Your other pots probably did the same thing, but the plants used more of the water.

Drew,
Not trying to be argumentative but......
The size of the metal screen holes may be a problem but definitely not anything to do with electrostatic charge and surface tension. And if by some far out chance you were right then the poly/fiberglass strands could hold a charge as well(maybe better). Any material in contact with water and soil will dissipate the charge anyway. There would not be enough surface tension to hold back the hydrostatic pressure of a PWT.

I agree that the opening size was the most likely problem since I used fiberglass window screen. When I pulled the window screen out, it was completely caked with "moss mush" because the moss had migrated to the bottom.

Using dry wall tape with larger openings sounds like a good way to go.

I don't think it was the screen that made the difference. It was probably the volume of peat in relation to bark, and I'm wondering how micro the micro bark is?? It's not unusual for soils bade from fine materials to support 6" or more of perched water that won't drain on its own. To see if it was actually the screen, use a tall container (12" or more) filled with the soil and with a drain hole covered by screen. Completely saturate the soil and see if it drains. I bet it will. I think the water the OP is talking about is simply perched water.

There is a threshold level of large particles that must be maintained; otherwise, the ht of the PWT and aeration of the soil above the PWT will be the same as that of only the fine ingredients.

The threshold level changes when there is not enough fine material in the soil to fill all the air spaces between the chunkier material. From that point, the less fine material you have, the better will be the aeration and the lower will be the ht and volume of perched water. Once there is enough fine material to fill all the air spaces between the coarse material, you essentially have all the unwanted properties of just the fine material.

This is why growers who tell you to mix your potting soils with 50% perlite aren't doing anyone a favor. If the perlite isn't coarse and it doesn't meet the threshold standard, you might as well not bother. One thing perlite DOES do is reduce the volume or perched water a soil can hold - but it does little for drainage or aeration unless it meets or helps to meet the threshold standard.

What perlite does for soils in bark bases soils is, it gets lodged between the often flat bark particles, which opens up a LOT of additional air space in the mix. Other particles would work just as well in that regard, and some even hold water internally, which can add to water retention w/o sacrificing aeration or drainage. Eg, substituting Turface or calcined DE for perlite can make a significant change in water retention, which in some cases can be a good thing, but in others a not so good thing. Keep in mind that what's most convenient often comes at a price paid in the form of something not in the best interest of the plant.

It's always up to the individual to sort that part out, but the grower who demands a week-long interval between waterings shouldn't be trying to convince others that it's best for their plants. Soo many problems erupt when one grower is viewing the growing experience from the perspective of what's best for the grower, while someone else's view is focused on what's best for the plant. Very often the two are mutually exclusive.

Al

Micro Bark is one of the more consistent barks available here in the West...it's fine-grade "Orchid Bark" by E.B. Stone, just in a different package. It is uncomposted, and although there are some long "spear" particles, I'd say that 95% of the bag is useable for the 5-1-1.

Josh

"I agree that the opening size was the most likely problem since I used fiberglass window screen. When I pulled the window screen out, it was completely caked with "moss mush" because the moss had migrated to the bottom."

As Al suggested, I don't think the screen is to blame -- that's what I use in all of my terra cotta and plastic pots, and I've never had a problem like you're describing.

To add some additional information.

The container I had problems with is about 16" deep. I had two 1 gph emitters watering the container. After the first watering cycle timed out after potting, the entire container was full of water. Even after about three hours, there was still standing water at the top of the container.

When I noticed the problem, I began to re-pot the daphne in the container. I scooped out the completely saturated mix around the plant and removed the plant. I then dug down to where there was no more than 2" of mix left in the bottom. Even then, there was no drainage and the water just sat in the container above the level of the mix. Finally, when I removed the screen, which was completely plugged with "moss mush", the container drained completely.

I then re-potted the daphne using the same mix. However, the second time I didn't water the mix as I was potting. After re-potting, everything seems to be OK, and there is good drainage, just like the other containers I did.

My conclusion is that watering the mix during potting, combined with using window screen, was the primary cause of the problems. While there may have been too much peat in the mix, I think it was the watering that forced the peat to migrate to the bottom and seal off the screen. Since there was still three inches or more of water standing in the bottom of the container, above the level of the mix after I removed everything, it wasn't just perched water, it was complete blockage of the drainage.

As I indicated, next time I will use less peat, or use something else, and won't water things until everything is potted. I will also go to using dry wall tape mesh to have larger openings.

When I put together a mix, all the ingredients have already been allowed to absorb water, before being combined. It is difficult to evenly water a mix when any of the ingredients are dry. Calistoga Al