I have often been asked to help re-pot
trees and bushes that have become too large for the existing pot. It is standard practice to put a few rocks or bits of broken pots in the bottom, to facilitate drainage. Almost always, I find that the old drain rocks are completely surrounded by soil and that the drain hole is plugged with
roots. Pots are more likely to be over watered than a larger area of soil, and they are more likely to become completely dry when forgotten for a while. The tray beneath the pot often stores
water from pots that drain out too well. The plant sends roots through the drain hole, in search of that water. I don't grow anything of my own in pots. Too much pissing around. But, for
city dwellers on balconies and patios, they are needed.
Hugelkultur pots --- Rather than using drain rock at the bottom, I now use
wood and a variety of garden trash. My intent is to build a drain that won't clog right away and to create a filter, so that it takes longer for soil particles to reach the drain hole. The new drain material also absorbs water and releases it slowly. I start off with large sticks on the bottom. They are chopped up with my loppers. Then I incorporate all of the leaves, stems and general trash that accumulates from other potted plants that have died. In the example below, my friend had accumulated 5 grocery bags of trimmings that spent a few months in the bags. I was asked to haul this stuff to the organics dump and to buy a bag of soil.
I explained that soil is made from dead plant material and it doesn't come in bags. All of this trash was put on top of the wood. I stood in the giant pot and scrunched it all down. Then I put in the
root filter --- Many trees and bushes that are pot bound, will grow a thick mat of fine roots. Even when not in a pot, some bushes do this. When I remove unwanted specimens, I shake all of the dirt from the fine roots, and save them for potting tasks. The big pot received a 2 inch layer of root filter. This will slow the migration of soil into the
hugelkultur drain. I absolutely hate those plastic filter cloths. My root filter does the job without poisoning the world with plastic.
The photos are from bottom to top. The largest wood isn't visible, since I thought of documenting the process after I was well into it. Dirty hands and cell phone cameras don't go well together.