I was just talking with Katskan (Dave) about similar via email. I use the net type pond containers, and actually have a preference for colander-type containers with lots of slots/holes that I buy at the dollar store. He was asking the same ? as you, and I told him that I look at these containers as an ICU for slow or sick plants. They are capable of producing rampant growth if you're willing to stay on top of irrigation/fertilization needs.

I have found though, that circling roots are in large part a symptom of a 'too heavy' soil. The roots are at the perimeter of the soil mass, not in search of nutrients or water; in fact, roots do not 'search' for anything. They grow where cultural conditions are favorable, In container culture, roots are more often circling the container because that's where the AIR is. I find very little 'circling' in the well-aerated soils I use. Roots generally colonize the entire soil mass very evenly, & long, circling roots only appear after the plant has become much more root-bound than I should have let it become. In heavy soils, I've seen almost immediate evidence of circling roots, which I take as clear evidence of a poorly aerated or over-watered soil.

Al

Thanks, that all makes sense, actually in most of my 5-1-1 mix from you, the roots are dense and evenly distributed in the container. Maybe I can get some for my really stubborn plants like dwarf Gardenia.

My concern with the air-pot is to keep it moist, with peat based 5-1-1 mix, I think it's going be hard to keep the mix close to the holes from becoming water repellent. Or you just have to merge it into water. Or I could use your gritty mix, which you have to water every two hours.

I am just kidding to say watering every 2 hours, but you know what I mean, gritty mix + air-pot, it's lots of air, even a rat can survive inside the pot.

But I think there is still an improvement with the air-pot, with the 5-1-1 mix, the roots are a lot denser around the bottom than the upper part. I know the gravity works that way, I didn't see any of my container plants roots actually going upwards. With the air-pot, maybe I can make a better usage of the container volume.
YT

I have been using the Air-Pots for a couple of years now. I grow fig, pomegranate and peach trees in a mix of mulch (~40%), perlite (~40%) and expanded shale (~20%). Even those trees which are under-potted (up to an inch and half trunk caliper in a 3.4 gallon container) can go two days without water... many can go three days. However, I do try to water more often to reduce the temperature in the container.

My experience with them is that they do their job... sort of. There are still a few roots that find their way around the perimeter of the container, also, the coarse medium can turn some roots back into the container, etc. Overall, the roots are more fibrous and far fewer circling roots than when I used solid walled containers... which I don't see myself using more than occasionally.

~james

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Thanks James, your setup looks neat and clean. I am sure the trees are very happy.

May I ask how big are those containers in the picture?

Assuming you've done everything right from seed to planting out, air pruning root is far superior to traditional method. All the information is in Plant Production in Containers II by Carl Whitcomb. Great stuff.

Passive air-pruning is a temporary measure and doesn't take the place of the selective root pruning and root maintenance of woody material in containers for the long term.

Al

I agree it's not a good idea to grow trees in the same container with air pruning method in the long run. It is meant for out planting at appropriate time. New roots can consume the whole container rather quickly if left in too long. Again, still much better than traditional smooth sided container for out planting but probably not for primarily container growing for long term. I've seen far too many terrible root system grown in the smooth sided containers esp 15g and larger. Again, I'm talking about growing trees in the container before planting out. I have Rootmaker container, rootmaker seed starter tray and smart pot. I'm liking them much better than using Styrofoam cups, traditional stuff that most nurseries use these days.

Hi all. As Al mentioned, I'm just starting to try growing seedlings in aquatic plant baskets to get more airflow to the root zone. I just repotted a single white pine seedling into a basket over the weekend as an experiment. I realize this is certainly the wrong time of year to be repotting anything around here, but I had an extra seedling so thought I'd try experimenting a bit just to see what happens.

I used Al's Turface/pine bark/granite soil mixture, and increased the amount of Turface and decreased the granite slightly. Even though pines generally prefer drier soil I will be watering the seedling every day since most of the water runs out of the container.

I'm using the Aquascape 3.5" x 3.5" x 4" basket shown in this link:

http://www.inyopools.com/Products/12601355038851.htm?CS_010=38851&CS_001=1013946&CS_002=1016676

I found several of them at a local landscape/pond supply retailer for about $1.00 each.

Hope this helps.

Dave

YT,

The ones in the pictures are 3.4g containers. I grow them off the ground in the trays to avoid root-knot nematodes. I have seen evidence of RKN on every fig tree in Houston that I have examined the roots on. So far, I've only them in about 10% of my containers and most of those were ones which spent time on the ground.

I do not substitute using Air-Pots for periodic root-pruning. I am hoping to extend the time period between root work activities though. When speaking with a rep (I don't remember if it was an Air-Pot or RootMaker rep) it seemed as if he was telling me the proper use of air-pruning containers is the step them up (without bare-rooting)... when the plant outgrows one container, simply put the root ball into the next size up and back fill with more growing mix. I do not do this. I have bare rooted nursery grown trees that had gone through this process and the inner core was unbelievably hard.

~james

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This is shantung maple (Acer truncatum) that I pulled out of 18 cell tray (each cell measured at 4 inch depth and 3.5 inches across at top). I think I planted the seed in May so that's about 3 months of growing in it. I have potted it into 1g rootmaker then I probably will repot it in 3g Sunleaves white grow bag to be sold or given next fall.

I also have grown taxodium (species is unknown at the present, either montezuma or bald cypress or hybrid of both; it's a big mystery) and rootmaker starter tray gave me really nice root system development on these cypress seedlings. I have some growing in 5g rootmaker and some in 1g rootmaker as an experiment for the fun of it.

When done things right, they can really grow fast. I had asked a shantung maple grower for many years of how much his seedlings have grown in the first year and he said usually 6-12 inches. Mine have already reached a foot. I haven't measured them but I think they are around 14-16 inches. That's what happens when you have that kind of root system to absorb more water and nutrients leading to more growth. I have seen very impressive growth from Dr. Carl Whitcomb with his trees using rootmakers and others.