When I started growing small vegetables in wicking boxes, they were so successful that I wanted to extend the concept to something that would take the deeper and more extensive root system of a tomato.
Enter wicking tubs. I’ve written about how I made them here. Just for the record, I now have a total of 31 wicking boxes and 8 wicking tubs. It’s almost pathological!
One of the wicking tubs is beside the steps that lead up onto the deck. There’s also a grapevine planted beside the steps which is trained up the railing and onto the deck. That becomes relevant as you’ll see.
Of all the wicking tubs, the plants in this one struggled. I watered regularly but the soil on top always seemed dry. After watering, water appeared in the bottom of the inspection tube (using a dipstick to check), but didn’t seem to last. The other tubs behaved as they should have.
I concluded that somehow the plastic in the bottom must have become perforated and water wasn’t being retained in the reservoir. It still didn’t seem to be the cause of the dryness, even allowing for the extra watering, but there was nothing for it—the whole thing had to be emptied and checked.
As I started removing the soil, some fibrous roots appeared. I thought they were just the remains of the plants that had been growing there, but as I got further down, the roots became more numerous and bigger. As I got closer to the bottom, I tried to move the tub. No way would it move. Then I discovered why.
Ants had heaved up the soil around the base of the tub, which meant that the original drainage holes were covered with soil. That sneaky grapevine next door had decided to take advantage of the moister soil in the tub and had put a root through the hole without me seeing it. This is what eventually came out of the bottom of the tub:
The plastic had been perforated too, but only a few small holes. I replaced it and put back the soil, but not before putting the tub up on bricks to keep soil away from the holes. I checked the rest of the tubs and they were OK. Just shows how enterprising plants can be when there’s water to be had. No wonder they can uproot roads and houses.
Foodnstuff 
March 30, 2014 at 7:10 pm |
I’ve read about the boxes you made now. It’s really useful to read about thus watering system. Focussing the moisture in this way is really wise. Thank you.
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March 30, 2014 at 7:36 pm |
Better your wicking tub than your plumbing. 🙂 This made me smile. Cheeky grapevine!
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March 31, 2014 at 4:09 am |
If you have a chat to plumbers about what tree roots can do to water and sewer/septic pipes they would get very animated ;). Talking about wicked beds…Steve just designed a couple of large wicked brick (sealed) beds for a friends mum and it’s time to fill them with media. Just wondering what you use for your base layer (and your other layers)? I told him that I would ask you as you have been making wicked beds for ages now and know the pitfalls 🙂
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March 31, 2014 at 10:31 am |
I haven’t made a wicking ‘bed’ yet (as in ‘large’ wicking bed), only boxes (black plastic recycling crate type) and tubs, and I’ve filled those with all compost. Some people put gravel in the bottom and a layer of some sort of fabric on top to keep the soil from getting into the gravel. I reckon you want as much good composty stuff as possible (there’s no nutrients in gravel). The roots will get down into the wet layer whatever it is. Remember, water will only wick up against gravity about 30 cm, so you don’t want a very deep box or the top will always be dry.
You’ll need a pipe of some sort down to the bottom of the box so you can check the water levels with a dipstick. If there’s free water in the bottom of the pipe, then the bottom layer should be saturated. The original method for large beds was to lay a perforated pipe right along the bottom of the bed and vertical at each end. This is where you were supposed to add the water. I found that too slow (and not really necessary for my sized boxes), and now I just water over the top. You’ll see excess water coming out the drainage holes. That’s what happens when it rains anyway.
As I understand it, the idea is to have saturated soil at the bottom, where water-imbibing roots will grow and moist soil at the top (via wicking) where feeding roots will grow.
It’s the sort of thing where you learn as you go.
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March 31, 2014 at 12:30 pm |
Cheers for that excellent information Bev 🙂 These beds are pretty large, bricked and waterproofed. They have the pipes like you have mentioned and an overflow is designed into each bed in order to drain the water into the main drainage system. If you are interested I will send you photos of what they look like. They are going to be used for shrubs so the roots should have no problem getting to the water. It’s a very interesting project and one that was proposed thanks to us learning about water wicking through your site 🙂
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April 1, 2014 at 12:24 pm |
Would love to see some photos, thanks.
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April 1, 2014 at 12:48 pm |
I will send them via email. Steve has been documenting the process. Thinks it might be the start of something good. I think it might be the start of a garden…my money is on my interpretation being the most likely 😉
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March 31, 2014 at 7:49 am |
The commenter above looks like they’re talking about naughty beds….
That photo was incredible. Got to feel for the poor plants in the actual wicking bed. Imagine how thirsty they’d get? Still, I hope your grapes were luscious!
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April 1, 2014 at 12:24 pm |
That particular vine hasn’t flowered yet. It should have, it’s big enough.
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March 31, 2014 at 1:44 pm |
My mum used to farm grapes as a kid, with her family and she warned me never to plant a grapevine near the house. I didn’t think the roots would be any problem though.
Thankfully I haven’t planted a grapevine near the house (yet) but your pictures and story are a convincing testimony of my mother’s words. 😉
Mystery solved for you though. Bet that’s a relief!
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April 1, 2014 at 10:12 am |
Very intersting. That in an enterprising grapevine. I have been inspired by you to try some wicking buckets for my blueberry plants and will be careful now to put them where some sneaky root can’t get in. Cheers.
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April 1, 2014 at 12:21 pm |
I have a blueberry in a large tub. It isn’t a wicking tub, but I keep a large pot saucer under it always filled with water. It doesn’t seem to mind and sucks up the water quite happily.
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