Reusing Soilless Grow Mix Is It OK ?
Give it to me straight, can we re-use our specialty potting mixes? The stuff we use is a soilless commercial mix, that uses a peat moss base and has perlite for better drainage. We then add our own ingredients like earth worm castings,some guanos, kelp, etc. Further to that, through the crop cycle we brew and water in our own aerobic tea blends. We spend a lot of time, fuss and money on building up the health of our blend-should we really be throwing it away after? The plants we harvest are healthy, and we always flush with plain water for at least a week before we crop out. It really seems like a shame, and a bit of a waste. I’m no hippy, but “grow and toss” just doesn’t seem like the best possible answer.
We spend a lot of time, fuss and money on building up the health of our blend-should we really be throwing it away after?
Ok, my non-hippy friend, here is an answer that may work for you, as it has for others including myself. In short, the answer is YES, you can reuse your soilless mix(es) with great success. Now in the long version, I’ll explain when it’s an option and how you stand a better chance of making it work. Before contemplating reusing your soilless mix, make sure you have some experience with growing, especially if it’s for growing indoors under lights with specialty fertilizers, nutrients, etc. If not done right, it’s a great way to ruin a crop before it ever gets growing. On the bright side, if you reuse your mix for younger transplants, it’s not such a loss if you have to start a new batch if you don’t succeed in your first attempt.
• Flush well, very well, in the crop previous; it improves the quality of your harvests anyways
• Remove as much root debris as possible after letting medium dry out for a few days following a prolonged flush period.
• Break up and mix the material. This may mean emptying out pots and refilling later.
• Add some additional perlite, fresh earthworm castings and one cup of dolomite lime per commercial “bale” of mix you used first.
• Re-wet with a healthy compost tea, adding enzymes and microbes is also recommended
• Let the soil “rest” for a few days (at average growing temperatures) after re-wetting before transplanting
• Reuse mixes that have been watered with an abundance of products that contain hormones.
• Reuse mixes that have had ANY applications of strong PGRs that “halt” vertical growth.
• Reuse mixes where crops have had insects, root diseases, or serious issues with over fertilization or deficiencies with fertilizers.
• ONLY reuse mixes where you know what’s been fed to the crop and for how long previous-you are carrying over fertilizers, to some extent, from one crop to the next when you reuse the soilless mix.
Erik Biksa has been writing about and discussing hydroponics growing, related technologies and cropping methods since 1999 in a variety of professional publications and platforms globally Erik has travelled the world learning and teaching modern growing techniques and technologies and is appreciated by many growers for his informative yet hands on approaches. Presently, he is the Editor at Grozine Hydroponics Mag.