You don't need to worry about what is below the pots. Just the wicks will do. Wick needs to go as high into the pot as the material will perch water inside the pot.

I've got some woven polypropylene material that wicks like a fire hose. This is the black stuff used under pond liners. It's very tough and long lasting. If the pot were elevated and this material were stuffed in the bottom and dangling down below, it would wick the water right out. I'd want it touching earth or dangling 4-6 inches in air. I'm not sure how much "lift" it has but it will wick the water right out of a pail if you leave one end in pail and other hanging over the edge and extending below water level..

Cool. Good info on the poly material. Yeah, I want to wick out of the pot, not up into the pot. My goal is to use traditional potting mix (not 5-1-1 or gritty) and allow for trees to wick with the earth. I have some trees that don't seem do well in 5-1-1. But I don't want them to get waterlogged.

Do you think the soil would stay healthy for a number of years with an earth wick? I'm imaging this as a kind of mini raised bed -- as long as the pot (30-45 gal) is big enough, wouldn't there be microbe action inside? Or do I need direct soil-to-soil contact to allow the pot to act more like a raised bed?

Even without soil contact, your containers will develop microbes. All of my larger pots end up with a host of organisms, whether they're in the garden or elevated on the deck....and my mixes are all bark or grit based.

My only concern with the traditional mix would be compaction and sinkage...where the mix level drops significantly over the years. That will compromise the roots, especially those in the lower level of the container.

Josh

Hey Josh, good points. My goal is to try and create a mini raised bed with a fabric pot. I still want the roots to air prune and don't want the tree to get full size (avocados will get 50ft). I don't have any raised beds -- do those need to be filled each year? Or do the worms and whatnot keep the soil healthy? Any way around the soil drop in a raised bed?

Hey!
Raised beds need to be "topped off" or "refreshed" every year. Some folks buy potting mix or compost and add that to the beds; other make their own compost and add it; while others still actively compost and mulch their beds to keep the volume level. Newspaper or cardboard, leaves, old container mix, manure, et cetera, all piled into the beds over the Winter is a great way to fill the beds and fight weeds.

Raised beds are going to have lots of organic matter, which will break down and require replacement. You could incorporate some durable grit to increase the structure - perlite, pumice, turface, DE. Bark, as well, but not too much.

Josh

Jay:

My experience is that once the roots fill the container settling stops. I've had the settling issue with blueberry. The key is to fill the pots with roots asap, one yr or less. The mix doesn't settle after that. Blueberries don't need repotting but about once every 6 yrs or longer. They don't circle even a round pot like trees or figs.

You couldn't keep microbes out of your potting mix no matter what you do. There are billions in every handfull. I've never been concerned about that and my trees produce great.

Yeah ... I've never had to "top off" an actual raised bed (that is in contact with the ground). Containers get dumped every year or two and the contents added to the compost.

I don't grow in containers much any more, though that could change next year. I'm quite limited in open space for a garden here. I'm thinking of building my own Veggie Trugs next spring. This is a large container and not really a "raised bed" because it has no soil contact.

On the other hand, I use mulching materials that (eventually) add to the soil, and there is the compost going into the beds. The mulching encourages earthworms - my raised beds are typically bursting with earthworms. And they help by pulling material down into the soil, aerating and churning things up down there, and generally keep the soil light and fluffy.

That doesn't work so well in actual containers though. I'm not sure how I'll treat the home-made veggie trugs yet. That's way too much potting mix to discard every year. I'll have to experiment and see.

Hey guys, thanks for the info. I think I'm going to try a combo of bark, peat, pumice and DE. I'm imagining that will keep the soil level from dropping too much before the roots fill out and provide more support.