Thank you all for the advice. Chris, James: My apologies, I have not yet learned the proper terminology. Yes, I should have said something like "living mulch" or "companion plant" instead of "cover crop". I have no intention of tilling the soil. I will gladly eat any strawberries that any of the plants may offer, but so far I was only targeting the space between my blueberry plants as being exclusively for the strawberries. In the rest of my bed I grow other things, like tomatoes, peppers, squash, and fennel. I was a bit concerned seeing how much the strawberries have spread out in just one year, but then I wondered whether it would be better to just let them grow into the rest of the bed as long as I make sure the other plants have chance to grow taller than the strawberries. Last year was my first year for this bed, constructed using compost and wood chip mulch (a la the Back to Eden documentary), so I am still in the learning stage. Other sources that I have read/viewed more recently say that while wood chips are all well and good, I should get even better results if the bed always has something growing in it, live roots of some sort. So whether I get berries from them or not, it seems like a good idea to let the strawberries spread to provide those live roots.