When it comes to root health, pots with gas permeable walls carry the day. Terra cotta clay pots are better than plastic or vitrified clay pots and fabric pots are better than terra cotta clay. The reason is greater gas exchange through container walls and the fact that an increase in gas exchange comes with an increase in evaporative water loss, which can be a lifesaver when using water retentive media. There will still be a PWT in these pots, and for any given medium it will the same ht in a pot with rigid sides as in the fabric or air pots at container capacity. Container capacity is a measure of how much water the grow medium in a pot or container holds at the moment it has stopped draining after having been watered to the point of complete saturation. The ht of the PWT and how long it affects root function is usually key/critical in determining what opportunity a plant will have to realize as much of its genetic potential as possible (within the limiting effects of other cultural influences). The factor that most affects the ht of a PWT is the size of the particles from which the medium is made. So, reducing the duration of PWTs limitations increases the opportunity for plants to realize a greater measure of their genetic potential. But wait! There's a more important consideration. If you place your fabric containers directly on the ground/soil, from the perspective of hydrology it changes the fabric container to a raised bed; this, because water is free to move through the fabric between the grow medium and the earth, with the earth acting as a giant wick. This means, because of the increase in the force of adhesion in the mineral soil beneath the pot (due to a mineral soils much larger o/a surface area on a per volume basis), water in the soil will be pulled downward with enough source to overcome the capillarity holding it perched in the container. As long as you don't place the fabric container on coarse sand, peastone, or other large particles, the earth will likely pull all perched water from most media one is likely to use in a container. I've mentioned this and the fact that healing in your pots situating them directly on top of soil turns them into raised beds. the only caveat being it's essential that there is a 'soil bridge' so there is continuity of the soil column between the soil (earth) and the grow medium in the container, through the drain hole(s), so water doesn't have to jump an air gap to exit the container. This applies more to pots with rigid walls and is not a factor when discussing fabric containers. Al

Hi, rina. I know wood chips are different than bark, but I saw a nursery that was using these mixed with some alder saw dust. In about a year it turned to this incredible black, rich "soil". The guy as the nursery said it breaks down better and more nutritious for the soil and depletes less nitrogen in the process. The wood chips I was seeking are about the size of medium bark in nurseries. In retrospect, I am glad I didn't try that. Works great outdoors, not sure about containers! The black bark is essentially composted evergreen tree bark. I say evergreen because it could be a mix of a number of different types here in the Pacific NW --- hemlock, fir, ceder, spruce, etc. I didn't screen it, it seemed plenty loose initially; small to medium size in comparison to bagged nursery store bark. It would have been o.k. had I added the peat and perlite per the formulas given here. Screening would have left just the larger pieces, but that would be quite a chore for the volume I was using! I repotted some of the plants using the 5:1:1 formula with my black bark and those are doing much, much, better. A gardening friend said "Think of it...bark is like big saw dust. If you pack it down it gets as hard as a board". That is essentially what happened when I used the black bark alone without the the perlite and moss. ;(

Hello Al - thanks again for all of your posts and the fruits of your research. I am growing four heirloom tomato plants in containers using your 5-1-1 mix. Here in Raleigh the closest thing I could find to pine bark fines was a product by Timberline called "Soil Conditioner" which seems to be close to the ideal size. But I wanted to ask you two questions, which I hope you have the time to answer (and patience, if you've already answered them - I looked and could not find your thoughts on these): 1. I used a run of the mill mulch to top off my 5-1-1 mixes in the pots and to my dismay discovered the mulch was full of fungus gnats. I will try Gnatrol to get rid of them, but it brings up my question - what do you use for mulch for the 5-1-1? Maybe pine bark nuggets instead of this buggy shredded hardwood I'm using? (large size might help to avoid insect eggs or other stuff hiding inside?) Or do you not mulch? 2. And secondly, what do you use for day to day pest control? I'm spraying insecticidal soap almost daily to kill the whiteflies/thrips/aphids that I see on the leaves but I wonder if there's anything better I can do instead of using the toxic stuff (Sevin, etc). Thanks!

Thanks for the kind words, B&C. In Mississippi, Memorial day would be a good target date for repotting the fig. Hibiscus need an annual repot. Do that toward the end of March, before it starts growing in earnest. Apple and most deciduous trees should be repotted just before or at the onset of spring budswell. Cactus - ask the cactus experts at the cacti/succulents forum. Desert rose - in Mississippi - June Umbrella plant - June There are ways to mechanically limit the amount of perched water a planting will hold, even if you're using a very water-retentive medium. Eliminating all or most of the perched water allows the grower to use media that would otherwise be or border on the edge of unusable. This outlines ways to cope with heavy (water-retentive) media Another effective way of dealing with media that hold too much water is through the use of ballast. You can read more about that technique here: Ballast ..... For now, checking your planting's moisture level regularly with a 'tell' will make a difference in your plant's appearance and level of vitality. Here's something I wrote about that: Over-watering saps vitality and is one of the most common plant assassins, so learning to avoid it is worth the small effort. Plants make and store their own energy source – photosynthate - (sugar/glucose). Functioning roots need energy to drive their metabolic processes, and in order to get it, they use oxygen to burn (oxidize) their food. From this, we can see that terrestrial plants need air (oxygen) in the soil to drive root function. Many off-the-shelf soils hold too much water and not enough air to support good root health, which is a prerequisite to a healthy plant. Watering in small sips leads to a build-up of dissolved solids (salts) in the soil, which limits a plant's ability to absorb water – so watering in sips simply moves us to the other horn of a dilemma. It creates another problem that requires resolution. Better, would be to simply adopt a soil that drains well enough to allow watering to beyond the saturation point, so we're flushing the soil of accumulating dissolved solids whenever we water; this, w/o the plant being forced to pay a tax in the form of reduced vitality, due to prolong periods of soil saturation. Sometimes, though, that's not a course we can immediately steer, which makes controlling how often we water a very important factor. In many cases, we can judge whether or not a planting needs watering by hefting the pot. This is especially true if the pot is made from light material, like plastic, but doesn't work (as) well when the pot is made from heavier material, like clay, or when the size/weight of the pot precludes grabbing it with one hand to judge its weight and gauge the need for water. Fingers stuck an inch or two into the soil work ok for shallow pots, but not for deep pots. Deep pots might have 3 or more inches of soil that feels totally dry, while the lower several inches of the soil is 100% saturated. Obviously, the lack of oxygen in the root zone situation can wreak havoc with root health and cause the loss of a very notable measure of your plant's potential. Inexpensive watering meters don't even measure moisture levels, they measure electrical conductivity. Clean the tip and insert it into a cup of distilled water and witness the fact it reads 'DRY'. One of the most reliable methods of checking a planting's need for water is using a 'tell'. You can use a bamboo skewer in a pinch, but a wooden dowel rod of about 5/16” (75-85mm) would work better. They usually come 48” (120cm) long and can usually be cut in half and serve as a pair. Sharpen all 4 ends in a pencil sharpener and slightly blunt the tip so it's about the diameter of the head on a straight pin. Push the wooden tell deep into the soil. Don't worry, it won't harm the root system. If the plant is quite root-bound, you might need to try several places until you find one where you can push it all the way to the pot's bottom. Leave it a few seconds, then withdraw it and inspect the tip for moisture. For most plantings, withhold water until the tell comes out dry or nearly so. If you see signs of wilting, adjust the interval between waterings so drought stress isn't a recurring issue. Al