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Keeping potting soil well hydrated presents a challenge when the mercury rises and the gardener gets busy.
I’m always open to new ideas which allow me to use less water and keep my potted gardens happy. I hate to water deeply, only to find a growing puddle seeping out of the pot. Water is a precious resource, and grows more so each year.
I’ve used water globes in some pots and hanging baskets for a few years now, especially when the pots are indoors. They deliver just the amount of water needed over several days, reducing both evaporation and the inevitable mess watering can make. The large one I use to keep our Norfolk Island Pine happy through the winter is a two piece contraption.
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Yes, I realize the spike should be deeper into the soil. The tree’s roots are so thick this was the best I could do! And it still works….
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A terra cotta spike, about an inch in diameter, stays embedded in the potting soil. The stained glass globe reservoir lifts out for filling. You invert the filled globe into the spike (very carefully) and then allow the water to wick through the terra cotta spike, into the potting mix, as the plant needs it. The tree grows happily, and I fill the globe about twice a week.
This is a neat system, and got me to wondering whether I could construct something similar for the large pots I keep out on our patio and deck all summer.
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My favorite, clean, pea gravel, comes with a lot of fine grit.
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I’m not keen on buying more globes for the outdoor pots. For one thing, the kit runs around $20. For another, our squirrels might just knock the globe out and shatter it while they explore the pots.
But tiny terra cotta pots are fairly cheap at the big box stores.
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Burlap over the drainage hole keeps potting soil from seeping out of the pot.
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I found stacks of little pots today for about 40 cents each at WalMart. So I’ve dreamed up a little gadget which should work reasonably well to help keep a pot hydrated in summer. I am going to try it out this spring and see whether it works.
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My idea is to construct a hollow, terra cotta column towards the middle of the pot, that will hold a reservoir of water. The water will then wick back out into the soil as it is needed. Unglazed clay, like these little pots, absorbs and holds water easily. Although solid, they work much like a sponge.
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I’ve positioned the first terra cotta pot a little off center, on about 2″ of potting mix.
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That is the main reason I generally avoid unglazed pots for planting anything except succulents: water evaporates from the clay pot pretty quickly. They need constant monitoring in summer’s heat. But that porous clay, which allows water molecules to pass quickly and easily through the pot’s walls is exactly what makes terra cotta good for watering devices.
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I put a few inches of potting mix into the bottom of the pot, and then began the tower. There is a little square of burlap in the bottom pot to slow water from simply pouring through its little drainage hole.
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I’ve added some slow release plant food in the next to the top little pot, and also sprinkled some into the potting mix.
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A thin layer of pea gravel in the bottom of each pot in the stack helps space the pots apart and again, slow the movement of water.
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I filled in with potting mix, as I built the tower, to hold it steady. This pot is planted up with Lily of the Valley roots, Convallaria majalis, found bare root in one of the little packs you find everywhere each spring. Lily of the Valley grows and spreads from rhizomes, and so should be planted shallowly. The package said to plant them an inch deep.
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The pot is topped off with potting mix, covering the newly planted roots about an inch deep.
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After topping off the pot with soil, I added a few little Strawberry Begonia divisions and a few Arum italicum seedlings. These have small root systems still, and so planting didn’t interfere with the Convallaria roots just beneath the surface.
It is still a little early here for planting up pots. Our last frost date, in April, is weeks away. Whatever goes into this practice pot has to be hardy!
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Strawberry Begonia divisions and Arum itallicum seedlings can be tucked into the pot without disturbing the Convallaria roots below.
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All three of these plants may be transplanted out into the garden in a few months when I want the pot for something else…. or not.
Maybe I will like this perennial arrangement enough to just leave it to grow through until next spring!
The very top little terra cotta pot is filled up with gravel. Although I watered the whole pot in thoroughly to settle the plants and wet the potting mix, I paid special attention to filling the little terra cotta reservoir.
In retrospect, I wish I had thought to soak the terra cotta pots before using them. Next time, right?
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Finally, I laid a layer of moss over all of the exposed soil to further slow evaporation. Mulching pots gives a nice finished look even as it reduces the need to water. The potting mix won’t splash around when it rains.
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In full sun, I would have mulched with gravel. But since these plants prefer partial shade, the moss will work just fine.
You might notice a few decorative stones in the finished pot. I often put stones beside little transplants to protect them. The stones give a little obstacle to curious birds and squirrels and protect the plant’s tender roots as they establish. Stones also tend to keep the soil beneath cool and moist.
I like how this pot came together. As all the plants grow, the terra cotta reservoir should disappear behind their foliage. But it will still be easy enough to find when I’m watering.
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In summer, or when I’m traveling, I could remove most of the gravel from the top terra cotta pot to make enough room to upend a plastic water bottle into the reservoir. While not pretty, the bottle would feed water, as it is needed, to keep the pot going when I’m not here to water! There are lots of possibilities here.
What do you think? You are probably clever enough to already see ways to improve this scheme.
Please share your ideas, and we’ll tinker around to make an effective, affordable, water wise system to make summer a little easier on us all. I’d love to see photos of your pots if you try out this idea.
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Woodland Gnome 2017
Forest Garden 