The convention wisdom is to plant them ~18" apart in matted rows and discard last year's mothers each spring. They are biennials, but will fool you into believing they can last longer. Don't be fooled! They will put out more daughter plants than you need. If not this year, PDQ. The matted row needs to be narrow enough for you to pick from both sides without stepping into it. Choose a space for your patch, -a row, then divide the space into your six plants and center them equally in the patch. It might look silly to you, but do it. They produce very little the first year, are plentiful the second year, and take up space from then on.
After disappointing production this year, your six plants will put out some runners. Make "U" shaped anchors out of something like copper wire. They should be 2 to 3" long; long enough to hold a runner in-place. The runners (stolons) will go out in several directions. You need to pin them to the ground spaced where you want them. After that daughter puts down roots another will spring from her, ad infinitum. By the time there are 3 or so daughters in a row, mother will have put out others. The six plants this year will have 7,493 daughter plants by September. If that's more than you wanted, too bad. If you like to plan your garden, you should make a decision on how many plants you want, the exact location where these prospective plants should be planted, guide the daughters to these locations, and stop the madness when the goal is reached. As each is firmly rooted, cut the umbilical. Mom won't take the hint. Be persistent. No plants should enter winter with stolons still attached. Lastly for the year: save your Popsicle sticks for use as markers for Mother plants. As soon as the productive season is over (in 2020), you will reach in and rip the six 2nd year plants out and throw them away. If the stolons are still connected, it's a big deal because of entanglements.
Each spring, mark each plant with Popsicle sticks which will be 2nd year, high production plants. Repeat, ad infinitum. If you didn't buy a good named variety, you will understand why that's a good idea and worth the expense.