Read This and Your Indoor Plants Will Thrive this Winter

Those of us here in colder climates are moving from outdoor urban agriculture season to indoor plant time. 

If you haven’t experienced using sub-irrigation (widely and erroneously called “self-watering”) to maintain your indoor houseplants I would highly recommend making some pop bottle planters to house your smaller tabletop plants. You'll be helping both your houseplants and the environment. That's a double green win. 

You may think that clay pots and saucers are the way to go. Not true, and you can easily prove it to yourself. Clay pots and fast draining soil mixes are merely band-aids to remedy the shortcomings of drench and drain top watering. 

Once you understand how it works, you will save plants, water and time by using measured sub-irrigation. Coupled with adequate light, sub-irrigation will give you green thumb powers you perhaps didn't know you have. 

Of all the methods I’ve used over the past 30+ years, pop bottle planters are the most informative because you can see everything that is happening. 

One thing that I can’t stress enough is to measure the amount of water you add to the bottom “water transfer” section. I’m reluctant to call it the reservoir because that term leads to misuse of “self-watering” planters. Misinformed users usually top off the reservoir, which leads to over watering. 

You want to add water to the planter when the soil moisture calls for it rather than the level of water in the reservoir. 

I recently showed the above collection of little Ficus trees in pop bottle planters to a very intelligent business friend. He is a very sharp guy. Incidentally, I had already introduced him to sub-irrigated vegetable grow boxes. He now has several of them on the roof of his building. 

He looked at the collection of plants in pop bottle planters and immediately commented “But there’s no water in them!” His intuitive reaction was based on faulty logic that the reservoir should have water in it at all times and that the plants would then be able to use what they need. 

This is precisely why so-called self-watering planters have a reputation for over watering. Purveyors of these planters along with misinformed houseplant educators have done a great job of misrepresenting sub-irrigation by using this inaccurate term. In the process, they have done a superb job of screwing up the houseplant market here in the U.S. 

Only those with enough patience to learn the tricky process of poke and pour watering continue to buy houseplants. Most folks give up after killing enough houseplants. It may not be the same as killing an animal pet but most of us don’t like killing any living thing, animal or plant. 

The evidence is obvious when I scan through photos of home interiors while doing my blog research. What I see is usually plant barren interiors or sickly looking plants. This need not be. 

Plants, unlike animals have no intelligence to turn water on and off, to drink or not drink if you will. If you constantly add water to the “reservoir” of a sub-irrigation planter you will surely drown the plant. Measure the water and the result will be analogous to a perfectly baked cake. You will have a healthy and happy houseplant or office plant.  

Try some pop bottle planters and you’ll see for yourself. 

 

Comments

[Rodolphe]

Hello,

Thanks a lot for your blog full of great advices and clarifications about sub-irrigation vs self-watering. Thanks to your blog, I've started a sub-irrigated pop bottle to graw a new ficus from a little branch.

I have a question though : what's your best advice on how to know when to add water to the bottom part?

It's great to read you! Cheers!

[Nathan Weselake]

Do you have to put the lid on the bottom of the pop bottle because some pics have it on and some off.

You stress the importance of "measuring" . Can you point me a direction where I can get a sense of what plants require what water initially?

Great info, will be back often.

[Greenscaper Bob]

These are good questions that I believe are of general interest. I'll answer them in a separate post. Thanks for the questions and the feedback.