Over the last few weeks I’ve been gradually doing some “maintenance” on the wicking pots. They have been a bit neglected since we started getting good rainfall at the end of last summer. I had a lot of work to do to construct raised beds in the shade tunnels, and over winter these were generally more productive than the wicking pots as well as representing a much larger surface area for food production.
However the low rainfall over winter, and the lack of any signficiant rain for nearly three months has meant that we have to start managing our water supply (all rainwater in tanks) even more carefully than usual. I’ve almost stopped watering the raised beds, and at least half of them are under a thick layer of barley straw, with nothing growing in them. It’s at times like this that the wicking pots come into their own.
The ongoing maintenance of the wicking pots amounts to regular fertilizing with alternating applications of worm tea (diluted to 50%), cow manure tea (10%), and (especially for leafy crops) diluted urine (10%). They also get occasional surface applications of the sludge from the cow manure tea production, and of course regular topping up of their mulch to control evaporation.
Over time I find that the soil in the pots becomes somewhat “compacted”, and some crops establish such a dense root mass that it is nearly impossible to dig into the soil. These issues are evident from a gradual decrease in their productivity and in the “health” of the plants.
Thai Basil and Spring Onions. The basil has already gone to seed after a long period of lush growth. After harvesting the seeds I pruned it to stimulate some new growth, so as to get more production before I am ready to replenish the soil.
I’m not sure how long these Spring Onions, Clumping Leeks and Clumping Shallots have been in this pot – it’s certainly more than 18 months. They’ve been harvested regularly by cutting the stems off at soil level. Now they’re starting to look a bit tired, so I’ll replenish their soil in the coming weeks.
For these reasons I like to take out the soil every 12-18 months and combine it with a mix of sandy loam from the drains on our access track, chipped horse manure, and fresh compost.
This pot was rejuvenated in early September (about 12 weeks ago) and planted with Kang Kung (Ipomoea aquatica) and Mint (on the left, partly obscured by the asparagus). Both have grown rather extravagantly, the Kang Kung more so than the mint because it responds to harvesting by becoming even more productive. The Mint was a bit of a mistake because I just noticed that it is popping up throughout the whole top of the pot – that’s what mint does, I just forgot about it. I removed the mint after taking the photo.
The experiment mentioned in the heading of this post refers to an attempt to find a way of using discarded “florist pots”. These come in various sizes and are like an overly tall plant pot without any drainage holes. Florists keep their cut flower stock in them. They are too tall to use as plant pots because the top of the soil gets dry while the bottom is still saturated. So I thought I’d do a quick experiment to see how they go as wicking pots. I just drilled four drainage holes around the sides about 250mm from the top, stuck a 500mm bit of offcut plastic water pipe down the side, filled up to this line with charcoal (leaving a depression so that the soil layer extends below the drainage holes) covered it with geotextile and added potting mix.
All I had available to plant in them was some Lemon Grass that I had to move out of a raised bed, so I put single stems of that into three of these wicking pots and also into three normal plant pots. Four weeks later two of the wicking pots have thriving clumps of Lemon Grass (the third has been a bit slow to get going) whereas in the normal plant pots it is struggling to survive. All have been given applications of diluted urine.
Lemon Grass thriving in a simple wicking pot. One of the four drain holes is visible. I won’t leave it in this pot because it isn’t wide enough to let the Lemon Grass grow into a large and productive clump, but it shows that the principle works.
The “funnel” makes it easier to fill the intake and also helps to reduce evaporation. It’s a recycled thread spool from Reverse Garbage in Brisbane.
You can see my original long post on making wicking pots here and a modification of that design here.
Do you have any novel ways to share for making or using wicking pots? What kinds of veg do you find grow well in them?
Sustainable @ Lockyer Valley 
Do you see any conceivable way to make permanent wicking pots for large bushes such as elderberry? I live in the US in south Texas and we have months of super high heat and no rain and some plants need more water than I can reasonably give them, especially when they are in the ground. I am building some experimental wicking beds using potting mix because it lasts so much longer without compaction. Love to hear your thoughts. Thanks!
Thanks for raising this interesting questions. Sounds like you are in a pretty challeinging climate there in south Texas. So one thing to consider first off is that whereas plants in the natural soil only feel the impact of the ambient temperature on their roots from what can be transmitted down through the soil.
As soon as you put anything in a pot then heat can be transmitted into the potting mix from the sides as well as the top. Of course the material in the walls of the pot would provide some insulation from ambient heat (unless of course they are solid plastic or metal. But if the pots are getting direct sunlight onto their sides thiis will be a greater impact than the ambient air temperature.
If you are using a “wicking _bed_”, is it set down into the natural soil? This would remove the above issues. Large and wide raised beds would help.
If you are using pots, than I’d suggest creating as much cool shade as you can for the pots themselves.
As for the internal design of the pots, I can’t come up with more ideas than I have presented in this blog. My experience with wicking pots, as with any activity involving the growing of plants, is that the old adage that the best fertilizer is the farmer’s feet applies here. Daily or near-daily attention to soil moisture and indications of plant stress. I get caught out when I have some urgent project come up that requires all my time during some part of summer (of course it’s more often that I “think” it is that urgent, and forget about the garden for long periods).. We can get several days of temperatures in the high 30s (deg C) with the night time temperatures in the mid to high 20s.
I haven’t tried it yet, but a highly adjustable drip irrigation system that drips into the water reservoir would go a long way to avoiding drying out of the growing medium. I can get simple adjustble drippers here that can reduce flow down to as little as one drip every few seconds. I use them for keeping the water up to bird baths – one dripper will take about three weeks to empty a 200L barrel if monitored and adjusted regularly.
An overflow hole in the side of the pot (I’m sure that is shown somewhere in the blog) would avoid excessive saturation of ths soil above – these holes were meant to cope with heavy rain periods, but would work to limit over watering with drippers.
I stll haven’t found a way to avoid the need to replenish “exhausted” soil every 18 months or so.
Please let me know what you think of these suggestions and what strategies you develop and how they go.
This blog has been sadly neglected for a long time – mostly because I’m on the management committee of a community group that is fighting the development of a rocket engine testing facility in a Koala Priority Area that is almost exclusively Core Koala Habitat, and the majority of the area around it is either National Park, Nature Refuge, or rural residential properties. We have been fighting this for three years or more.
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