Is it OK to reuse the run-off water?

newgen(9 Central California)March 25, 2013

Every time I water my Elephant Ear in the gritty mix, I see a fair amount of run-off. I also use a little Foliage Pro each watering as well. Is there any harm/good if I collect the water from the drainage dish and dump it back into the pot? This would help the gritty material get soaked better, because just a one-time run through with the water may not be enough to soak the Turface and bark. I normally water twice in a row at each watering just for this reason.


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sutremaine(UK S.Wales 9)

I would say water through once with plain water, discard the runoff, and then water again with fertilised water and recycle that water until you feel the mix is wetted enough.

    Bookmark   March 25, 2013 at 5:47PM
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Here is answer to your question - Al (tapla) answering someone else on House Plants forum (thread: Watering issues):

Posted by tapla z5b-6a mid-MI (My Page) on Fri, Mar 22, 13 at 9:53

One of the most significant benefits of using soils that allow you to water copiously with no concern about potential root problems related to excessive sogginess is the fact that the ability to flush the soil at each watering prevents dissolved solids (salts) from building up in the soil. Ideally, when you water you would allow the effluent passing out of the drain hole to run down a drain or collect in a saucer. When it DOES collect in the saucer, the container should be lifted above the effluent, so after it exits the pot, there is no way the dissolved solids contained in the effluent have any chance of getting back into the soil. I set my pots up on little 1-1/4" blocks that rest in the saucer. I don't need to empty the collection saucer because the water that collects there can't get back into the pot. It evaporates and contributes to the area humidity, but you could empty the collection saucer if you like, or water over the sink.
The higher the level of dissolved solids in the soil solution, the more difficult it is for the plant to take up water. So a soggy soil that impairs water uptake combined with a high level of salts in the soil solution is a double whammy for a large fraction of growers who use heavy soils that don't allow them to water so they're flushing the soil. This problem is always most prevalent in the spring, after a long winter of watering in sips, or in your case, of pouring residual salts back through the soil, which ensures a gradual but continual increase in the level of dissolved solids that affect water uptake AND nutrient uptake.

If you're using a fertilizer that might not be a problem if you're watering properly, it can quickly become a serious problem if you're NOT watering properly. We know the impact of dissolved solids on the uptake of water also limits the ability to take up nutrients, but when dissolved solids accumulate the ratio of nutrients to each other in the soil can quickly become skewed, which has the effect of one nutrient present in excess making it difficult or impossible for the plant to take up another nutrient. This is very common when using fertilizers with too much phosphorous, and is quickly exacerbated when the soil isn't flushed regularly.


Posted by tapla z5b-6a mid-MI (My Page) on Fri, Mar 22, 13 at 15:57

If you're using the gritty mix, there is very little possibility that you're over-watering, or that flushing the soil thoroughly would create a problem, so I would do that. If you didn't screen the mix carefully, and there are fines in the soil, then use a wick and tilt the pot after you flush - then water normally. I use a level 1/4 tsp/gal of FP 9-3-6 every time I water, and I've been well pleased with the results ever since I settled on that amount, so I'm thinking you could cut back on the amount of fertilizer you're providing. I'm pretty sure that with the 1/2 tsp/gal + the recycling of the effluent, that your plants are seeing some fertilizer burn.
There are some advantages to fertilizing every time you water, and at 1/4 tsp/gal, you get about 800 gallons of fertilizer from a quart of fertilizer. @ $25/qt for the fertilizer, a gallon of solution costs about 3 cents per gallon. Most people would hardly think twice about buying and paying for the electricity augment light levels for their plants - and that's a much more significant outlay than the small amount of fertilizer that might get discarded after passing through the soil. If you want to, collect the effluent in a bucket & spread it on the lawn or your garden/beds.

Plants that are fertilized at higher rates (luxury levels) often show symptoms of deficiencies when the concentration of nutrients in the soil returns to the adequacy range, so that's one + of fertigating @ each watering (it won't happen). Another is, even in nature, nutrient uptake is very closely linked (almost directly) to water uptake, the primary modifier being temperature, which isn't a particularly significant factor when houseplants are the topic. I said that so I can say there is some benefit in not having to keep track of what needs fertilizing when. I fertilize and water everything at nearly the same intervals, and at the same fertilizer rates, and for the last 15 years or so, my plants have all been practically free of blemished foliage. You're trying to do essentially what I (and many others) have been doing, so I expect that once you get the bugs worked out & get your dosages refined, you'll begin to see how easy it can be. I'm pulling for you! ;-)

    Bookmark   March 26, 2013 at 12:26AM
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calistoga_al ca 15 usda 9

Consider how much water and soap we waste taking a bath, yet who would suggest reusing it for the next bath? Al

    Bookmark   March 26, 2013 at 9:22AM
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newgen(9 Central California)

Thank you Rina! That explains everything.

    Bookmark   March 26, 2013 at 1:38PM
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Hmmm not reusing bath water is a good point. pondering to what is being said.... What works for one person wont always be consistent with what someone else is going to do ? OR Even in a remote chance of not over watering the possibilities of over watering still exist ?

Better yet Does a dormant plant need X amount of water in the first place only to water by recycle the catch ?

    Bookmark   March 26, 2013 at 2:08PM
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