There is a debate waging in gardening circles over the common practice of discarding potting soil in favour of fresh material every time a gardener transplants or repots a plant. Even Marie Iannotti is polling gardeners as to their use and re-use of potting mix.

Jeff Ball from Gardening and Yardening has rebutted the timeless advice offered by many a gardening expert, instead choosing to renew his potting mix and reuse it. But is it wise to counter expert opinion and go against the grain of traditional thinking?

At AllExperts.com, another subsidiary of About.com, resident gardening expert James L. Crowder is an obvious proponent of dumping used potting mix and advising gardeners to use fresh. In one piece of advice to a fellow gardener who was requesting suggestions for a struggling tree, Crowder finishes his response with "If you can repot it, throw away the old soil, don't reuse it.".

Without reading the question one might assume that the querying gardener has soil-borne problems that are killing her plant. However, the soil has nothing to do with her question. It's merely a problem with a rootbound tree that's too big for its current container.

So why does Crowder give her the advice to discard her potting soil?

Well, if you look back at where most gardening 'experts' get their knowledge from you will notice that they mainly come out of large horticultural industries or botanical gardens where plants are produced en masse. In this environment every aspect of potting; from the air quality, plant specimen, sterilization of potting containers and the potting mix itself, is imperative to be in prime condition.

If there were to be an outbreak of any form of disease in this climate their plant stocks would be devastated. Penn State University advises that "A potting mix that has been treated to kill plant pathogens or a soilless mix purchased with the assurance of being free of pathogens should be handled as if it were food and kept free of unwanted organisms."

So the big question for home gardeners is, "Do we need to be that safe when planting?" And the answer is an unequivocal "No".

Sure, home gardeners can still lose plants to soil-borne diseases but unless you're potting plants in vast quantities or you grow rare and exotic plants then reusing your potting soil is fine. Obviously you take a risk and even Jeff admits to falling victim to one of these but candidly brushes it off as a rarity.

To answer the burning question - it comes down to personal preference. If you're not worried that the potting soil may be infested and the likelihood of loosing some of your plants is a reality then reuse the mix as Jeff has prescribed. Otherwise, recycle it by adding to a 'hot' compost heap and find some fresh medium to grow your plants in.