Karin and Gus wrote:
>We have adopted a plot in a community garden that is filled with mint and
I totally agree with harvesting the mint and digging up some horseradish, but depending on the size of the plot, a little can got a long way.
As to the mulching method, I don't know what kind of wimpy horseradish you have in Pennsylvania, but here in Minnesota, that method would just enrage the horseradish and cause it to engage in a vendetta that could last for years! Horseradish has mighty deep roots, in fact I think it might be capable of disintegrating bedrock, if given half the chance. I've planted small pieces of in in 6 gallon buckets two feet deep, set into the ground so there was a 2 inch collar showing above the soil, and within a couple of yearws, the roots have escaped throught the bottom and established new plants. Better to carefully dig up everything to a depth of two feet, and be careful to remove every last bit of root--it may take a couple of years, but if you don't it'll be back.
Most mints are rhizomateous(think stinging nettle), and both peppermint and spearmint are extremely aggressive, spreading rapidly by sending out rhizomes. If one little piece of rhizome escapes notice, it will rapidly grow into another aggressive plant. They don't, however, go down as deep as horseradish.
So careful, deep digging or better still, double digging(this fall preferably, the roots and rhizomes have had all summer to store up energy for a burst of growth next spring), followed by cardboard and mulch(remember that woodchips rob nitrogen as they break down), as Doreen advised, and you'll have friable, fertile soil that other gardeners will envy next spring!
Diane Dodge, Ramsey County(MN) Master Gardener