Gardening Pots

How to Clean Smart Pots

Fiber pots can become dirty or stained over time. (And yes, the plants shown are marijuana, which can now be legally grown in many areas.) Photo:

Over the last few years, pots made of fiber, usually geotextile, have become very popular for growing vegetables and also marijuana. The best-known ones are made by Smart Pot, to the point where “smart pot” is often used as a generic name, but other brands you may see include FiberGrow, GeoPot, Root Farm, Root Pouch and Dirt Pot. 

Root ball of plant grown in a plastic pot compared to a plant grown in a finer pot. Photo:

The main advantage fiber pots compared to plastic pots is that they allow greater aeration to the roots and result in root pruning: fine roots near the edges of the pots are trimmed by exposure to the air, leading to improved branching, rather than roots circling inefficiently around the inside of the pot as happens in plastic pots. They also dry out more quickly, preventing overwatering. A further if somewhat minor advantage is that, if you empty them, they take up little space in storage, as you can fold them flat. However, since many gardeners never empty them, that’s rather a mute point.

The downside to fiber pots is that they require more watering; often much more watering.

Many gardeners really like them and see improved yields.

One question gardeners have, though, is how to clean them before reusing them (and they can last 7 to 10 years), so let’s look into that.

Do You Need to Clean Them?

A bit of staining or dirt is quite normal and nothing to worry about. Photo: Greengrower8

Actually, you don’t … at least, not in most cases and certainly not every year. Yes, dirt and stains can appear on the outside, but, people, we’re working with plants growing in soil … in other words, dirt. A bit of dirt or discoloration on the outside of a pot doesn’t really mean much. And for most of us, the appearance of the pot is of no importance as long as the plants you grow in them produce well. If a dirty exterior really bothers you, just use a soft-bristled scrub brush to lightly scrub the outside of the pot each spring … or just slip into a cache-pot.

Do note that you don’t need to empty fiber pots at the end of the growing season. You can leave them full of soil all winter, storing them outdoors or bringing them into a garage or potting shed, then reuse them with the same “old soil” the next season, probably adding a bit more growing mix or compost each spring, as soil does decompose. You can do this for years, until … something goes wrong.

Things That Can Go Wrong

White stains often indicate mineral salt buildup. Photo:

The appearance of white stains on the outside of the pot, most likely in where water is hard, can mean the soil is becoming contaminated with mineral salts that will negatively affect plant growth. 

Algae coating the outside of a fiber pot. Photo: III20,

The buildup of algae or moss on the outside usually means either you’ve been overwatering or the soil inside has become so compacted that there is little air circulation, but, in either case, that means the pots are no longer “breathing” as they should.

And then there are soil-borne plant diseases like fusarium, verticillium, sclerotinia and various root rots, even nematodes in mild climates (nematodes aren’t really a disease, but create disease-like symptoms). These can build up over time and considerably reduce yields. If you’ve been growing tomatoes over and over again in the same soil, for example, thus not carrying out crop rotation like you really should, this can become a problem.

So, at least every once every few years, you do have to dump out the old soil (you can put it in the compost bin or use it in the garden) and thoroughly clean your fiber pots.

How to Clean a Fiber Pot

Washing fiber pots in a washing machine is the easiest solution. Photo:

Here’s how to clean a fiber pot, step by step. 

  1. Dump out the soil and let the pot dry. 
  2. Gently brush off the exterior with a soft-bristled scrub brush to remove dirt and stains. 
  3. To get out all the soil and dried roots clinging to the inside of the pot, rub the pot sides together and dump them free or clean the inside with a vacuum cleaner.
  4. To sanitize the pot and kill any microbes, you’ll need to wash it, either in the washing machine (most efficient and much less work) or by hand in a tub or bucket. Use a laundry detergent with non-chlorine bleach or a stain remover like OxiClean to get the worst stains out while essentially sterilizing the pot. 
  5. The washing machine will automatically rinse the pot, but if you hand-wash, rinse thoroughly with fresh water.
  6. Allow the pot to air dry. Do not put in a dryer.

The pot will now be clean and disease-free. You can either store it, folded (you see, that did turn out to be useful after all!), until the next season if you cleaned it in the fall or reuse it immediately if you cleaned it in the spring. 

Now, that wasn’t difficult, was it?

Garden writer and blogger, author of 65 gardening books, lecturer and communicator, the Laidback Gardener, Larry Hodgson, passed away in October 2022. Known for his great generosity, his thoroughness and his sense of humor, he reached several generations of amateur and professional gardeners over his 40-year career. Thanks to his son, Mathieu Hodgson, and a team of contributors, will continue its mission of demystifying gardening and making it more accessible to all.

13 comments on “How to Clean Smart Pots

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  9. We clean around 64 to 128 at a time. It is not easy to get them clean especially if the root system is impressive. We use Coco as a medium which is easy to dump but the roots that penetrate the walls of the pot are…let just say a bit of a pain in the a**, Is there anything you can use to breakdown the roots before cleaning?

    • You could probably leave the empty pots in a pile under moist conditions for several months so the roots bits would rot and come away more readily.

  10. I still do not use them, mostly because of the (intended) fast turnover of what I grown in conventional cans. I do not want to keep them canned long enough to get circling roots. Also, I do not want to water them more. (Of course, much of what is out there now has been canned much too long.) For nursery production, because we grow commodities that have a much slower turnover, we do not want bags to get dirty and mossy. Rhododendrons somehow do not develop many circling roots.
    Smart pots have a bad rap here because they are what the pot growers use, and then dump on the sides of the roads everywhere, or leave strewn about rented properties after they thrash them and move out.

  11. Christine Lemieux

    I am curious as to why the soil can be used over again. I always thought potting soil had to be replaced each year? Thank you.

    • Companies that sell soil find great advantage in recommending replacing soil yearly. I think the reason for this idea comes from that. Logically, though, you don’t replace the soil in your garden yearly, in fact usually never: you just add amendements over time. There is no major difference to soils used in pots. The major exception would be plants very susceptible to soil diseases, like tomatoes. Even then, you’d not necessarily have to change it annually, but maybe every 4 years or so.

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